Point of Clarification: ESP32 is not exempt from the issue as is the case with BetaFPV SuperP using GPIO1 on PWM14. If an ESP32 does not use GPIO1 for a PWM output, it will not exhibit the issue as is the case with Radiomaster ER6 and ER8.
@@Filmaker25 there's a lot going on here. Your question is a bit vague. If you want to be able to design these systems, then probably computer or electrical engineering. If you want to write software for these systems, then definitely computer science. If you just want to learn more, then physics... specifically, electromagnetism, or e-mag, re-mag, and 3-mag as they called it when i was in school :)
@@banzaiibdamn I just wanna know which reciever will work with my tx16s and give me the most range 😅 Also I plan on getting the elrs ranger module so I need it to work with that too
@@EnglishTurbines wait I don't think I as clear; my tx16s has built in elrs so I'm trying to stick with that(protocol?). Isn't crossfire a different system(protocol?)? Would that mean I also need a crossfire module for my radio to ransmit and recieve data from the drone with a crossfire reciever?
Thanks for going through the work of creating the list. There are a number of non pwm receivers in the list that would not be affected by this issue though.
@@darrenehlert6100 Good catch! Thank you. I pared it down to just the receivers that have "PWM" somewhere in the json, and it's now a much shorter list.
I am an Industrial Electronic and calibration technician, for 40 years, retiring the end of this month. This issue may be similar to some of the electronic noise issues I've encountered in recent years with modern motor controls, AC and DC. The newer digital servos may be throwing noise on the dc buss and the receivers may be getting 'confused'. It may be worth a try to install a small RF choke on all red servo wires, or if you can find a ferrite torroid(? spelling) (iron powder doughnut)that will allow you to pass the servo lead through and wrap around 2 to 3 times. If you have or can borrow an oscilloscope and monitor the voltage buss especially on power up you may see the noise.
Thanks John! Showing once again why your channel is the absolute best regarding edgetx and elrs. Great work and nice catch! Thanks for all you do for the hobby!
Thanks for the video. I'm looking into using ELRS with my cars and, well, they are all PWM. Worse still I use programmable servos. Safe to say I'm regretting my decision right now. This will probably result in using a receiver with more channels than needed and map the output somewhere else to avoid the issue.
John, this is a great piece of sleuth work by you and the ELRS devs! Imagine how much hair-pulling you have probably saved us by putting out this video!! If this alone isn't worth a Patreon subscription, I don't know what is! 👍👍
Great job John! I'm glad you guys caught this and hopefully there's a quick solution for it. And thank you for the dedication to this hobby and for other people. You're a good man! John
ER6-G and ER6-GV are both not affected as they are on esp32 hardware. Same for ER6 - despite what you say at 16:40. At least if I've understood how to look up the chipset in targets.json.
Interesting - so the video point saying ESP32 aren't affected is wrong. Mine are on DLG gliders, so I'm using tiny KST X06 servos. Only the latest version of these that I have are programmable. @@geoffh7206
I clarified in the video and in a pinned comment the ESP32 isn't exempt, but there are more pin assignment options on those boards. I apologize for the confusion on this point.
Started to have problems with my ELRS 915mhz DIY receivers a few months ago. Used the PWMP flash and only have three channels with chan one being the problem. Wouldn't connect when that servo was connected. Simply made a buffer with a 2n2222 transister and two resistors (1K and 10k) . Works great, never looked back!
It is a problem to be aware off. The incredible thing is that ELRS is so well done with the flexibility to remap pins that the workaround was already there :) really great to know, thank you very much!
an other issue with the er6GV ? i have this receiver in a glider together with a TX16S (Edge 2.8.5). I have put the logs on the SD switch. The logs starts when the altitude is at least of 3m . As soon as the logs start the radio goes into emergency mode and you loose the signal of course. I tried an other receiver with this set up and this issue does not happen demonstrating that it is not an edgetx or ELRS problem . maybe this issue is linked to what you describe ??
Thanks for this. It explains the problem I discovered a few weeks ago on PWM2 output pin on two receivers (Matek R24-P6 and BayCK PWM RX) with a Savox SH0255MGP servo. Upon powering up, even before bind was achieved, the Savox servo on PWM2 was driven slowly to full lock and beyond the physical stop in an aileron linkage, damaging the linkage. I tried some other servo brands but they didn't have the same problem. I just moved the servo to another PWM output to work around the problem. Both receivers turned out to be ESP8285-based.
I use ER4 for my tank and tracked robot. Its worked perfectly for a month and then this morning it is stop working. I only use channel 3 & 4. I thought my ESC was burned but then I try the same receiver for my tank it is also not worked. Try to rebinding it and no luck. I try my fpv drones and all working so definately my receiver. Is it related to what you experienced? It is the throttle that not worked.
Great Video! You really do a HUGE service to the ELRS community! Do you think you can do a new setup video for these new Radio Master receivers? I haven't seen any in depth videos on RUclips, only quick mentions that they exist.
Hello. I have same tx12 controller, and er5c receiver. Do i need external transmitter to connect er5c with tx12? Or it will work with internal transmitter and protocol crossfire?
I recently put a BetaFPV ELRS Micro Receiver (PWM) in an old foamy with Hitec HS-65HB servos and they buzzed like crazy - constantly as soon as the power was plugged in. Really weird. I ended up swapping for some tower pro digital servos and they worked fine. I checked and that RX has the ESP8285 chip so now I'm wondering if that was the issue.
This is a fairly limited use case related to PWM pin 2 on the 8285 chipset and potentially other PWM pins on ESP32 chips as we saw in the BetaFPV SuperP (Ch14). So I doubt it. Be aware with ELRS you can specify the PWM duty cycle, so you need to make sure what you set is appropriate for your servos.
@@RCVideoReviews I just checked and the TX and Receiver Packet Rate is 333Hz (full) and in the RX the Output Mode is at 50Hz. I wasn't sure what to set that to so I left it low. I also plugged in the Hitec servos that were buzzing and now they're not buzzing and seem to be working fine so yeah I probably had something set wrong at the time. This was my first time installing an ELRS PWM RX and had no idea what I was doing - still don't lolol
Good plan leaving the PWM cycle low if you don't know. Servos should indicate their PWM frequency on spec sheets. Only use the higher rates if the specifications indicate support for them. The rate between the TX and RX is just that, it's between the TX and RX.
I have a Matek ELRS-R24-P PWM receiver and there is a problem that, when I connect the battery, it doesn't always work. Sometimes the transmitter and receiver bind and everything is normal. But often when I connect I get the esc beeps (number of cells in the battery) but the receiver doesn't become active. This receiver has the ESP8285 chipset so maybe it has a problem?
@@RCVideoReviews I'll give that a shot when I get home. I recall changing the packet rate on the TX following the advice to smooth out channel 5 when assigning a full range channel to those pins on the receiver. He didn't mention changing the rate on the receiver but I didn't question it.
This is actually a bit more of a problem with surface models because ch2 is the (long established standard) for the ESC signal. So the uart output causes the ESC to give a burst of full throttle on power up, which can be very nasty with a large scale vehicle. I guess it would be equally nasty if you had an ESC driving a planes prop on the affected channel? This is the sort of behaviour you might expect from a 1980's AM radio system, very poor that the latest, greatest 2.4 digital receivers have this hardware 'bug'. The Radiomaster ER3C receiver is their primary elrs receiver for surface models, and afflicted by this. I guess moving the throttle/ESC to ch3 should help, but feels a bit of a bodge.
If I am not mistaken, this could very well be a silicon bug in the ESP32 & ESP8285 chipsets. If I am correct here, this also is not possible for manufacturers of our receivers to do anything about it either. The only ones what can do anything about it is the chip vendor, & that's Espressif. Considering I _have_ the same ESP32 chipset in a handful of Adafruit development boards, it would be interesting to see if the same bug applies there too.
Also, the end device should be protecting itself from un-chartered data. I would be interested in hearing what you find out about the development boards.
@@RCVideoReviews Indeed. It will be a few months before I start doing that. I recently moved house, & left two of my helicopters (plus half my development boards) behind. So, I will be going back at the end of November to retrieve what I had left behind. ...& yes, it would actually be worth looking into. My ESP32 development boards have the ESP32-S2 chipset (which only has WiFi). I _do_ want to get my hands on the ESP32-S3, because that is (IIRC) one of the targets that ExpressLRS uses. I can't remember if it's the -S3 variant or the -C3 variant. Also, I looked on Espressif's website & it doesn't look like they have issued any notices regarding this bug (I have my doubts that even they may be unaware of it). Stranger things have happened...
It's not a bug. GPIO1 is serial TX on UART0. The bootloader will always spit out some data on power up, and this behaviour is known and documented. The hardware designers either shouldn't have used this pin, or could perhaps have gated the signal in some way until the system has booted. Alternatively, if you hold GPIO15 low, it will disable the output from the first stage bootloader (and you can configure the second stage to not output anything). But the 8285 doesn't have this pin, so you can't do it... By the same token, the servo shouldn't disable itself after receiving a few random bytes either!
As far as I am aware Open-TX radios (Non ELRS) send the stick and button data as a packet to the external module every 9 milliseconds. They send the packet via UART with BAUD 100,000 with a Start Bit, 8 Data bits, Even Parity, 2 Stop bits. What happens with the Open-TX packet for ELRS and PWM? I don't really understand is this an external module? Is the radio sending 15 individual PWM signals one for each channel? How you connecting 15 cables to the radio?
I've mentioned this issue in the Elrs group and also to Betafpv (I bought Betafpv micro receiver 5 pwm) in March this year but got no respond like its only affected my harware lol. Ch1 and Ch2 only can be used with my digital servos, not working with my analogue servos. I checked with oscilloscope at affected Channel the voltage level is only 2.8V. All good Channel is 3.4V. I tried to pull up those channel to 3.4V using resistors and it works normally. But I didn't check if it will impact programming ability. 🤷
@@RCVideoReviews I have checked originally Ch1 and Ch2 signal rail is pulled to the Gnd, while the rest is pulled to the Vcc. This rx just has 5 pwm output so I can't afford to lose 2 by mapping to another pin.
Could this cause my throttle not to work on a betafpv pwm micro (orang and black) receiver? I've updated my receiver to 3.3 everything works as far as Aileron, Elevator and rudder go but I cannot get throttle to work at all.
I would love to see more videos from you with Helicopters. Including using ELRS with telemetry on your helicopters. I am looking for RX to replace my FrSky RXs for both planes and Helis (I use iKon2 FC in my helis). For my helis, I am hoping to have the Main Battery Voltage and the Brain2.luac script for configuring the IKon2 from my radio work. Anything else would be a nice bonus.
If you use binding phrases on Tx and Rx, you shouldn't have any issues binding. Just flash each device with ELRS configurator and use a binding phrase in the configurator. It's quite simple and effective.
It's not in targets as that receiver definition uses layout_file to define some values - have a look in RX \ Vario 2400.json for the pwm_outputs - pin 1 is there. Good to know KST X08 isn't a problem.
Thanks John, could you clarify if ESP8285 is not safe to use at all? your sample (moving PIN1 servo to other PIN) , i understand it's only for ESP32. right?
Not at all, I use ESP8285's all the time. It's not a reliability question. It's a question of the boot process causing one known brand of servo to react strangely on one pin. This was an awareness video to help explain what's going on in the event it pops up with other programmable servos.
Kind of related question... until this video I did not know that my affected Savox digital servos were programmable. Any chance you could do a video on what this means, and whether they can be programmed via an ELRS TX?
Servos can't be programmed via ELRS. Most of them have some kind of proprietary programmer. In the case of Theta servos, the belief is they see this chatter on PWM pin 2 and it causes them to enter programming mode. That doesn't mean ELRS is a servo programmer.
@@RCVideoReviews Thanks for the response. Savox do not make a programmer, but several posts I found about programmable servos said that 'modern TX can do this built in', hence my question. If it's not an ELRS feature, that's fine. Before this morning I didn't even know they were programmable. 🤣
Hmmm, I'm not aware of any servo programming capabilities on EdgeTX via ELRS or any other protocol. Not saying they don't exist (could be done via LUA like FCs etc..), I'm just not aware of any.
Hello John! Would it be possible to show in a video what occurred with your receiver and what you did to remap the elevator? I am just getting started after purchasing a new Radiomaster TX16S transmitter and ELRS receivers. I know many of the Radiomaster receivers are unaffected by this hardware bug but it would be good to understand this glitch before one of us loses a plane. Thanks!
This would be really handy, as it's somewhat glossed over in the ELRS documentation about this handy feature. It's mentioned in a limited amount in under Channel Mapping and Failsafe, but only for the web UI - no mention that it can also be done on transmitter via the ELRS Lua and the Other Devices section.
Peter, I've seen some strange behaviors manipulating the channel map via lua then comparing the results in the WebUI. I haven't stopped long enough to do a specific repeatable test--I will. But right now, I prefer to use the WebUI for channel remapping. Electricflyer: I might be able to sort out a video. I'll think about the best way to do it as the servos are all in the plane, and I **just** finished setting all throws. So I don't want to take it apart. Let me see what I can do.
I had this issue on my RM ER5A when using Savox digitial servos last week, was discussing on ELRS Discord last week. I resolved it in the same way, moved that channel to a different output.
@@AtlayGaming Hey man how did you actually do this? I'm a nube that bought rm er5a and had it connected to my elrs system. Bound well but could get no stick movement in Betaflight. Could you please tell me how to solve this?
ER8GV is also impacted and according to radiomaster its affect only some servo (MKS for example) (tis is what i have been told by radiomaster ...... its a shame that they still sell these receiver without a clear warning in the user manual
Many thanks for this alerte John, as usual you are a great support for all of us. Just some questions. If the issue happen a startup, then I suppose it cannot happen in flight (out of receiver reset in flight). Am I right? Or is there still any risk? I don't really understand how to find the "bad" channel. For exemple on betafpv superP you said it's channel 14, is it because pin1 is on the 14th pwm outputs? When it's on an ESP 8285 is it always on channel2?. Also when It happened to your Theta servo, was it repeatable or just randomly?
It can only happen on the receiver booting up, with the servo connected, to pin 1. When the receiver powers up, pin 1 outputs signals, which can make some programmable digital servos that look for a signal on startup to go into their programming mode. Once the code is running that will not happen, the pin is under the control of the ELRS firmware. However, if you have a receiver power brownout, well, that means the receiver could reboot, so it could happen in midair - but you also had a brownout. For the BetaFPV Super P, it is indeed CH14 because 1 was listed in the 14th channel of the pwm_outputs list. Basically, anything ESP8285 will always be CH2. If the receiver has an ESP32, it has a lot more pins, so you need to check if the troublesome pin 1 is mentioned in pwm_outputs. If there is no pwm_outputs entry for that receiver, you need to look in the relevant layout_file file instead for that pwm_outputs list.
Peter, This was my exact concern in flight--brown out. Aside from the inconvenience of cycling the impacted servo on boot; a brownout would be a bad thing.
@@pfeerick Many thanks Peter for this very exhaustive and clear answer. I hope all brand will updated their design/layout to avoid using pin1 very soon for new products. Nevertheless on curent products I think if we don't use proprammable servos there is no issue, hopefully I don't have one ;o) only simple digitals, and I have already a betafpv superP, but in any case channel 14 is not so easy to use on this receiver, then I can still use it safely. By the way I found this is a very good receiver.
One clarification though, this isn't really considered a design flaw. In order for certain features to be able to work, they need to use the PWM pins as serial communication channels. So I'm not sure what the programming fix will be; however, I think it starts with Theta and perhaps a shift to ESP32s instead of ESP8525s where more pins are available and more options are available to the developers.
I got the jta slick and used the er4 with agf BO5CLS servos and dam is it snappy. Bwtween the high speed of the servos and the low latency of elrs its without a doubt the most responsive plane I have. Definitely going with elrs rx with my planes in the future. Hopefully they come out with some higher channel counts. Like 8 10 or 12 ch recievers would be cool
Excelente trabajo 👌. Actualmente cuantas marcas hay de receptores PWM ELRS? Sinceramente solo conocía los de Radiomaster y ahora que veo por tu vídeo los de happymodel
@@RCVideoReviews Muchísimas gracias por la información. Ahora me pongo manos a la obra para buscar información. Por qué prefieres utilizar en tus aviones este sistema de módulo PWM/ELRS sobre ejemplo el módulo multiprotocolo de Radiomaster? Cuáles son esas características que te han animado a utilizarlos? Por qué si ELRS ofrece más confiabilidad otras marcas como Spektrum o futaba que son maraca TOP no lo utilizan? En teoría es mucho mejor que sus protocolos DSMX, FASST.
Spektrum y otros están invertidos en sus propios protocolos. Uso ELRS por varias razones: 1) La modulación LoRa tiene un rango excepcional. Usando poca potencia, puede volar por millas. Usando una potencia más alta (pero aún dentro de las limitaciones de ISM de la Parte 15), el enlace de control tiene un alcance que supera a todos los protocolos convencionales. 2) Flexibilidad: un protocolo admite CRSF para modelos con FC/FBL y ahora Gyros. Admite SBUS para otros Gyros/FC que no admiten CRSF. Admite PWM para modelos con conexiones directas desde RX a servos. 3) Precio: uso receptores de $ 13.99 y tengo un enlace de RF asombrosamente confiable con todos mis aviones. No tengo ningún uso para los receptores de $ 70 que hacen menos. Te animo a unirte a nuestra discordia para seguir conversando.
@@RCVideoReviews Ohhhh... Valla veo por donde vas y realmente todo parece mejor que utilizar esas marcas caras por menos que ELRS. Tengo que confesar que hay puntos que mencionas y no entiendo jaja, pero comprendo la idea. Muchísimas gracias por tomarte el tiempo para ayudarme, lo aprecio mucho. Otro aspecto que me da extrema confianza en ELRS es verte utilizar aviones carisimo (por lo menos para mí). Para que te hagas una idea de los equipos que abundan en Cuba, pues aún en se vuela gran parte con radios de cristales, utilizamos casi siempre los servos futaba s3003 estándar para nosotros en aviones construídos por nosostros mismos en otras maderas que no son balsa. Pero esto es una parte linda del hobby. Ya estoy en el Discord, últimamente lo reviso mucho y estoy algo al tanto de los chat, pero me es un poco complicado por el idioma. Saludos desde Cuba 🇨🇺
I just stick with radiomaster. Had a matek take down a $500 model when it failed. Servos. Eh. I’ll stick with ProModeler, MKS, Emax, & some old Airtronics, Futaba & Hitec.
@@Toysrme i’ve been flying crossfire on all my planes and quad coppers for a long time never had a problem ever.. I just bought the ELRS system haven’t tried yet. Now I’m kinda afraid i’m not saying it’s not a good system but.
Thanks for this awesome analysis. Jacob Scherer did a latency test with a radiomaster er3c-i and showed that for this reciever PWM channels 1 and 2 show garbage during boot: ruclips.net/video/OfxvGxojPYc/видео.html Can you say why also channel 1 shows garbage in this case? Thanks alot.
Oh I dunno, aside from the fact you can change these values: • Dead zone • Pulse input range • Max current • Output range • Soft start • Current protection • Neutral range • PWM Center Pair that with the fact these servos support 8.4v input and provide Torque/Speed @ 8.4V of 22kg/.07 60 deg compared to Hitec 225MG analogs which caps at 6v and max torque of 4.8kg and .11 60 deg Why would I settle for that on a plane that can push these higher end servos to their limits? Finally, the subject plane was an RxR of which I already KNOW ExtremeFlight has sold out and will continue to fly off the shelves--Why not look at the root cause? So don't buy a top shelf RxR with SUPERB servos pre-installed, or worse, remove the pre-installed servos and replace them with lower performing analog servos OR Move ONE WIRE from PWM2 to PWM6 Yeah, real song and dance. Tough choice.
@@RCVideoReviews Maybe for someone that requires all those features then changing PWM2 to 6 is not a bad work around. However I am not sure how many people that uses ExpressLRS wants or needs those programmable features. Personally I like ExpressLRS because of simplicity, light weight, small foot print and good range. So if I have to sacrifice by using some other brand or type of servos no deal breaker. Especially when you are talking about the ER6GV. That is a receiver best suited for a glider with a narrow fuselage. No need for a 22kg/.07 servo.
Your context is obviously different than the context in which this situation arose. The blanket statement "use different servos" is not an appropriate answer just because your use case doesn't require the same servo capabilities as the one in this situation. There are different needs for different craft. In this case, the craft benefits greatly from the servos used. The RF tech should not be a deciding factor in that choice.
![Radiomaster ExpressLRS PWM Receivers [ELRS] : ER4 • ER6 • ER8 • ER6G • ER8G • ER6GV • ER8GV](http://i.ytimg.com/vi/FUyy1zy45OQ/mqdefault.jpg)
Point of Clarification: ESP32 is not exempt from the issue as is the case with BetaFPV SuperP using GPIO1 on PWM14. If an ESP32 does not use GPIO1 for a PWM output, it will not exhibit the issue as is the case with Radiomaster ER6 and ER8.
what would the right subject to study if I wanted to learn more about this subject?
@@Filmaker25 there's a lot going on here. Your question is a bit vague. If you want to be able to design these systems, then probably computer or electrical engineering. If you want to write software for these systems, then definitely computer science. If you just want to learn more, then physics... specifically, electromagnetism, or e-mag, re-mag, and 3-mag as they called it when i was in school :)
@@banzaiibdamn I just wanna know which reciever will work with my tx16s and give me the most range 😅
Also I plan on getting the elrs ranger module so I need it to work with that too
@@EnglishTurbines wait I don't think I as clear; my tx16s has built in elrs so I'm trying to stick with that(protocol?).
Isn't crossfire a different system(protocol?)? Would that mean I also need a crossfire module for my radio to ransmit and recieve data from the drone with a crossfire reciever?
nice workarounds and very well presented therefore subscribed to hear more from your channel about fixed wing stuff.
Good info, thanks! Here's a list of the affected models from the json file:
BETAFPV PWM 2.4GHz RX (esp8285)
BETAFPV SuperP 14Ch 900MHz RX (esp32 + pin 1)
HappyModel EPW5 2.4GHz PWM RX (esp8285)
HappyModel EPW6 2.4GHz PWM RX (esp8285)
MATEK R24-P PWM 2.4GHz RX (esp8285)
RadioMaster ER4 2.4GHz PWM RX (esp8285)
RadioMaster ER5A/C 2.4GHz PWM RX (esp8285)
Thanks for going through the work of creating the list. There are a number of non pwm receivers in the list that would not be affected by this issue though.
@@darrenehlert6100 Good catch! Thank you. I pared it down to just the receivers that have "PWM" somewhere in the json, and it's now a much shorter list.
Thanks guys! This is the type of community and collaboration I love to see around RCVR. Thank you!
Any idea if this will also affect the ER3C-i PWM receiver that comes with the new MT12 surface radio?
I am an Industrial Electronic and calibration technician, for 40 years, retiring the end of this month. This issue may be similar to some of the electronic noise issues I've encountered in recent years with modern motor controls, AC and DC. The newer digital servos may be throwing noise on the dc buss and the receivers may be getting 'confused'. It may be worth a try to install a small RF choke on all red servo wires, or if you can find a ferrite torroid(? spelling) (iron powder doughnut)that will allow you to pass the servo lead through and wrap around 2 to 3 times. If you have or can borrow an oscilloscope and monitor the voltage buss especially on power up you may see the noise.
The developers have captured the output on GPIO1 before ELRS is loaded with no device connected. I'm told it's mentioned on the data sheet.
Thanks John! Showing once again why your channel is the absolute best regarding edgetx and elrs. Great work and nice catch! Thanks for all you do for the hobby!
Thank you for the comment. Appreciate it.
Thanks for the video. I'm looking into using ELRS with my cars and, well, they are all PWM. Worse still I use programmable servos. Safe to say I'm regretting my decision right now. This will probably result in using a receiver with more channels than needed and map the output somewhere else to avoid the issue.
John, this is a great piece of sleuth work by you and the ELRS devs! Imagine how much hair-pulling you have probably saved us by putting out this video!! If this alone isn't worth a Patreon subscription, I don't know what is! 👍👍
Thanks Geoff! Appreciate the kind comment. I'm glad to help.
Very interesting. Vbat telemetry alone is worth running elrs.
100% agree. It's a requirement on all of my planes now. Nothing goes up without vbat.
Great job John! I'm glad you guys caught this and hopefully there's a quick solution for it. And thank you for the dedication to this hobby and for other people. You're a good man! John
Thank you Robert, appreciate the kind words. I think the solution us use ESP32 based RXs if you have programmable servos.
ER6-G and ER6-GV are both not affected as they are on esp32 hardware. Same for ER6 - despite what you say at 16:40. At least if I've understood how to look up the chipset in targets.json.
For the ER6-G and ER6-GV, you then need to look at RX \ Vario 2400.json for the pwm_outputs, and CH2 is pin 1, so they are affected.
Thanks for the additional clarification Peter.
@@pfeerick Well spotted Peter! Strange that they chose to use pin 1 for the ER-6G and ER-6GV, yet were able to avoid it for the ER-8G and ER-8GV.
Interesting - so the video point saying ESP32 aren't affected is wrong. Mine are on DLG gliders, so I'm using tiny KST X06 servos. Only the latest version of these that I have are programmable. @@geoffh7206
I clarified in the video and in a pinned comment the ESP32 isn't exempt, but there are more pin assignment options on those boards. I apologize for the confusion on this point.
Thanks John just so glad you weren't in the air when this happened. Thank you so much for sorting this out for us. Very much appreciated
You're very welcome. Remember this is a boot time issue, not a reliability issue.
Started to have problems with my ELRS 915mhz DIY receivers a few months ago. Used the PWMP flash and only have three channels with chan one being the problem. Wouldn't connect when that servo was connected. Simply made a buffer with a 2n2222 transister and two resistors (1K and 10k) . Works great, never looked back!
It is a problem to be aware off. The incredible thing is that ELRS is so well done with the flexibility to remap pins that the workaround was already there :) really great to know, thank you very much!
Yup, the workaround is simple enough. This stumped me at the field for about half an hour.
an other issue with the er6GV ? i have this receiver in a glider together with a TX16S (Edge 2.8.5). I have put the logs on the SD switch. The logs starts when the altitude is at least of 3m . As soon as the logs start the radio goes into emergency mode and you loose the signal of course. I tried an other receiver with this set up and this issue does not happen demonstrating that it is not an edgetx or ELRS problem . maybe this issue is linked to what you describe ??
so. i assume there is still no fix for this?
Not something that can be fixed by ELRS team. It's a microcode issue on the chips.
Thanks for this. It explains the problem I discovered a few weeks ago on PWM2 output pin on two receivers (Matek R24-P6 and BayCK PWM RX) with a Savox SH0255MGP servo. Upon powering up, even before bind was achieved, the Savox servo on PWM2 was driven slowly to full lock and beyond the physical stop in an aileron linkage, damaging the linkage. I tried some other servo brands but they didn't have the same problem. I just moved the servo to another PWM output to work around the problem. Both receivers turned out to be ESP8285-based.
Thanks for the info on the Savox SH0255MGP. I'll pass it along.
I use ER4 for my tank and tracked robot. Its worked perfectly for a month and then this morning it is stop working.
I only use channel 3 & 4. I thought my ESC was burned but then I try the same receiver for my tank it is also not worked. Try to rebinding it and no luck.
I try my fpv drones and all working so definately my receiver.
Is it related to what you experienced?
It is the throttle that not worked.
Great Video! You really do a HUGE service to the ELRS community! Do you think you can do a new setup video for these new Radio Master receivers? I haven't seen any in depth videos on RUclips, only quick mentions that they exist.
Thanks for the comment. I'm glad to help. I could do an RX setup video...probably not a bad idea.
Hello. I have same tx12 controller, and er5c receiver. Do i need external transmitter to connect er5c with tx12? Or it will work with internal transmitter and protocol crossfire?
I recently put a BetaFPV ELRS Micro Receiver (PWM) in an old foamy with Hitec HS-65HB servos and they buzzed like crazy - constantly as soon as the power was plugged in. Really weird. I ended up swapping for some tower pro digital servos and they worked fine. I checked and that RX has the ESP8285 chip so now I'm wondering if that was the issue.
This is a fairly limited use case related to PWM pin 2 on the 8285 chipset and potentially other PWM pins on ESP32 chips as we saw in the BetaFPV SuperP (Ch14). So I doubt it. Be aware with ELRS you can specify the PWM duty cycle, so you need to make sure what you set is appropriate for your servos.
@@RCVideoReviews Thanks for the info! IDK what was causing the buzzing then but it sounded like electric hair clippers lol.
What is your pwm rate on the pwm pins?
@@RCVideoReviews I just checked and the TX and Receiver Packet Rate is 333Hz (full) and in the RX the Output Mode is at 50Hz. I wasn't sure what to set that to so I left it low. I also plugged in the Hitec servos that were buzzing and now they're not buzzing and seem to be working fine so yeah I probably had something set wrong at the time. This was my first time installing an ELRS PWM RX and had no idea what I was doing - still don't lolol
Good plan leaving the PWM cycle low if you don't know. Servos should indicate their PWM frequency on spec sheets. Only use the higher rates if the specifications indicate support for them. The rate between the TX and RX is just that, it's between the TX and RX.
Being programmable, are Torq servos affected like the theta servos or is this just a limited rare impact.
I have a Matek ELRS-R24-P PWM receiver and there is a problem that, when I connect the battery, it doesn't always work. Sometimes the transmitter and receiver bind and everything is normal. But often when I connect I get the esc beeps (number of cells in the battery) but the receiver doesn't become active.
This receiver has the ESP8285 chipset so maybe it has a problem?
Set the init rate on the rx to match the packet rate of the tx in the configuration you’re using.
@@RCVideoReviews I'll give that a shot when I get home. I recall changing the packet rate on the TX following the advice to smooth out channel 5 when assigning a full range channel to those pins on the receiver. He didn't mention changing the rate on the receiver but I didn't question it.
can i use yappu telemetry with these receivers? thanks
It is all very interesting, although I tend to use cheaper servos most of the time. Keep the good work you do up!
Thanks! Will do.
Thanks so much for the vid.
Ya, i think those who work with esp32 for microcontroller projects are aware of "safe" and "unsafe" GPIO Pins to use.
This is actually a bit more of a problem with surface models because ch2 is the (long established standard) for the ESC signal. So the uart output causes the ESC to give a burst of full throttle on power up, which can be very nasty with a large scale vehicle. I guess it would be equally nasty if you had an ESC driving a planes prop on the affected channel? This is the sort of behaviour you might expect from a 1980's AM radio system, very poor that the latest, greatest 2.4 digital receivers have this hardware 'bug'. The Radiomaster ER3C receiver is their primary elrs receiver for surface models, and afflicted by this. I guess moving the throttle/ESC to ch3 should help, but feels a bit of a bodge.
Do you have a video instructing how to remap the outputs?
Actually been on my list for a while now. ruclips.net/video/e5FDyN2knJU/видео.html
If I am not mistaken, this could very well be a silicon bug in the ESP32 & ESP8285 chipsets.
If I am correct here, this also is not possible for manufacturers of our receivers to do anything about it either. The only ones what can do anything about it is the chip vendor, & that's Espressif.
Considering I _have_ the same ESP32 chipset in a handful of Adafruit development boards, it would be interesting to see if the same bug applies there too.
Also, the end device should be protecting itself from un-chartered data. I would be interested in hearing what you find out about the development boards.
@@RCVideoReviews Indeed. It will be a few months before I start doing that.
I recently moved house, & left two of my helicopters (plus half my development boards) behind. So, I will be going back at the end of November to retrieve what I had left behind.
...& yes, it would actually be worth looking into. My ESP32 development boards have the ESP32-S2 chipset (which only has WiFi).
I _do_ want to get my hands on the ESP32-S3, because that is (IIRC) one of the targets that ExpressLRS uses. I can't remember if it's the -S3 variant or the -C3 variant.
Also, I looked on Espressif's website & it doesn't look like they have issued any notices regarding this bug (I have my doubts that even they may be unaware of it).
Stranger things have happened...
It's not a bug. GPIO1 is serial TX on UART0. The bootloader will always spit out some data on power up, and this behaviour is known and documented. The hardware designers either shouldn't have used this pin, or could perhaps have gated the signal in some way until the system has booted.
Alternatively, if you hold GPIO15 low, it will disable the output from the first stage bootloader (and you can configure the second stage to not output anything). But the 8285 doesn't have this pin, so you can't do it...
By the same token, the servo shouldn't disable itself after receiving a few random bytes either!
@@stevelupton2533 Thank you for clarifying this.
You have actually saved me from needing to test this out for myself. =^/.~=
i have a radio jumper t12pro with opentx.....do i need to buy another radio in order to use this er4 with voltage telemetry? thanks
As far as I am aware Open-TX radios (Non ELRS) send the stick and button data as a packet to the external module every 9 milliseconds.
They send the packet via UART with BAUD 100,000 with a Start Bit, 8 Data bits, Even Parity, 2 Stop bits.
What happens with the Open-TX packet for ELRS and PWM?
I don't really understand is this an external module?
Is the radio sending 15 individual PWM signals one for each channel? How you connecting 15 cables to the radio?
This issue is on the rx, not tx. I don't use OpenTX anymore, so can't answer what they're doing.
that video with its little quirkiness was the funniest this morning! LOL
Glad you enjoyed it
I've mentioned this issue in the Elrs group and also to Betafpv (I bought Betafpv micro receiver 5 pwm) in March this year but got no respond like its only affected my harware lol. Ch1 and Ch2 only can be used with my digital servos, not working with my analogue servos. I checked with oscilloscope at affected Channel the voltage level is only 2.8V. All good Channel is 3.4V. I tried to pull up those channel to 3.4V using resistors and it works normally. But I didn't check if it will impact programming ability. 🤷
Hmm, I think voltage should be consistent on the rail. I'd be concerned about that.
@@RCVideoReviews I have checked originally Ch1 and Ch2 signal rail is pulled to the Gnd, while the rest is pulled to the Vcc. This rx just has 5 pwm output so I can't afford to lose 2 by mapping to another pin.
Could this cause my throttle not to work on a betafpv pwm micro (orang and black) receiver? I've updated my receiver to 3.3 everything works as far as Aileron, Elevator and rudder go but I cannot get throttle to work at all.
Is throttle on Ch2?
No it’s on ch3
This issue relates to pre-firmware data on pin 2.
I would love to see more videos from you with Helicopters. Including using ELRS with telemetry on your helicopters. I am looking for RX to replace my FrSky RXs for both planes and Helis (I use iKon2 FC in my helis). For my helis, I am hoping to have the Main Battery Voltage and the Brain2.luac script for configuring the IKon2 from my radio work. Anything else would be a nice bonus.
Whew 😮💨 I'm glad I bought the Radiomaster ER6's and dodged that bullet, thanks for the information on this potential problem.
Yup, If you got the ER6/ER8 no change required on your part. Not too hard to deal with the others either via remap and/or radio configuration change.
I can not find if Radiomaster ER5C-i and ER3C-i are affected or not. I did not find them in json file... Please does anyone know?
ER3C-i is affected too, ER5C-i is also affected on the first 2/3 channels as far as I can see.
@@martijnklerks Thanks. How did you find it, please?
@@EddieVichta because I own them personally and I am affected by the issue hahahaha
Can you help me with binding of EPW6 to radiomaster Tx16 with axis thor crosxfire
If you use binding phrases on Tx and Rx, you shouldn't have any issues binding. Just flash each device with ELRS configurator and use a binding phrase in the configurator. It's quite simple and effective.
I Have some planes with 12 servos. Can I use two receivers in one plane/ radio to be able to use Elrs?
Yes. Turn telemetry off on one of them.
@@RCVideoReviews Thank's!
Does a Spectrum Transmitter does have any advantage to ELRS?
No
Wait, it's better at draining your wallet...
My helis stay frsky too. Crossfire doesnt have rpm in its telemetaey
Does the er4 radiomaster have this issue , was hoping you would say as you had it on the bench
running a er6gv has esp32, i don't see pwm output on channel 1 in the targets.json... running digital kst x08, no issues.
It's not in targets as that receiver definition uses layout_file to define some values - have a look in RX \ Vario 2400.json for the pwm_outputs - pin 1 is there. Good to know KST X08 isn't a problem.
Thanks John, could you clarify if ESP8285 is not safe to use at all? your sample (moving PIN1 servo to other PIN) , i understand it's only for ESP32. right?
Not at all, I use ESP8285's all the time. It's not a reliability question. It's a question of the boot process causing one known brand of servo to react strangely on one pin. This was an awareness video to help explain what's going on in the event it pops up with other programmable servos.
4 out of 6 channels just stopped outputting on a new matek r24 p6, wondering if this has anything to do with it
No. This condition is very specific to PWM pin 2 in the case of that Rx.
I just got the betafpv. Im confused on what you were saying on pin1. Are you saying all betafpv 14 channels have this or only certain ones?
I’m having this exact issue with the new mt12 Radiomasters ground radio with a futaba servo Rx is ERC5-i on channel 2
Kind of related question... until this video I did not know that my affected Savox digital servos were programmable. Any chance you could do a video on what this means, and whether they can be programmed via an ELRS TX?
Servos can't be programmed via ELRS. Most of them have some kind of proprietary programmer. In the case of Theta servos, the belief is they see this chatter on PWM pin 2 and it causes them to enter programming mode. That doesn't mean ELRS is a servo programmer.
@@RCVideoReviews Thanks for the response. Savox do not make a programmer, but several posts I found about programmable servos said that 'modern TX can do this built in', hence my question. If it's not an ELRS feature, that's fine. Before this morning I didn't even know they were programmable. 🤣
Hmmm, I'm not aware of any servo programming capabilities on EdgeTX via ELRS or any other protocol. Not saying they don't exist (could be done via LUA like FCs etc..), I'm just not aware of any.
Hello John! Would it be possible to show in a video what occurred with your receiver and what you did to remap the elevator? I am just getting started after purchasing a new Radiomaster TX16S transmitter and ELRS receivers. I know many of the Radiomaster receivers are unaffected by this hardware bug but it would be good to understand this glitch before one of us loses a plane. Thanks!
This would be really handy, as it's somewhat glossed over in the ELRS documentation about this handy feature. It's mentioned in a limited amount in under Channel Mapping and Failsafe, but only for the web UI - no mention that it can also be done on transmitter via the ELRS Lua and the Other Devices section.
Peter, I've seen some strange behaviors manipulating the channel map via lua then comparing the results in the WebUI. I haven't stopped long enough to do a specific repeatable test--I will. But right now, I prefer to use the WebUI for channel remapping.
Electricflyer: I might be able to sort out a video. I'll think about the best way to do it as the servos are all in the plane, and I **just** finished setting all throws. So I don't want to take it apart. Let me see what I can do.
can the BETAFPV ExpressLRS ELRS 5CH PWM Receivers flash by wifi?
I think so...
I had this issue on my RM ER5A when using Savox digitial servos last week, was discussing on ELRS Discord last week. I resolved it in the same way, moved that channel to a different output.
What servo specifically? I'd like to pass it along to the ERLS team.
@@RCVideoReviews I reproduced the issue with two Savox servo models, SC-0253mg and SC-0352
Thank you for the feedback. I will pass it along.
@@AtlayGaming Hey man how did you actually do this? I'm a nube that bought rm er5a and had it connected to my elrs system. Bound well but could get no stick movement in Betaflight. Could you please tell me how to solve this?
ER8GV is also impacted and according to radiomaster its affect only some servo (MKS for example) (tis is what i have been told by radiomaster ...... its a shame that they still sell these receiver without a clear warning in the user manual
Many thanks for this alerte John, as usual you are a great support for all of us. Just some questions. If the issue happen a startup, then I suppose it cannot happen in flight (out of receiver reset in flight). Am I right? Or is there still any risk? I don't really understand how to find the "bad" channel. For exemple on betafpv superP you said it's channel 14, is it because pin1 is on the 14th pwm outputs? When it's on an ESP 8285 is it always on channel2?. Also when It happened to your Theta servo, was it repeatable or just randomly?
It can only happen on the receiver booting up, with the servo connected, to pin 1. When the receiver powers up, pin 1 outputs signals, which can make some programmable digital servos that look for a signal on startup to go into their programming mode. Once the code is running that will not happen, the pin is under the control of the ELRS firmware. However, if you have a receiver power brownout, well, that means the receiver could reboot, so it could happen in midair - but you also had a brownout. For the BetaFPV Super P, it is indeed CH14 because 1 was listed in the 14th channel of the pwm_outputs list.
Basically, anything ESP8285 will always be CH2. If the receiver has an ESP32, it has a lot more pins, so you need to check if the troublesome pin 1 is mentioned in pwm_outputs. If there is no pwm_outputs entry for that receiver, you need to look in the relevant layout_file file instead for that pwm_outputs list.
Peter, This was my exact concern in flight--brown out. Aside from the inconvenience of cycling the impacted servo on boot; a brownout would be a bad thing.
@@pfeerick Many thanks Peter for this very exhaustive and clear answer.
I hope all brand will updated their design/layout to avoid using pin1 very soon for new products.
Nevertheless on curent products I think if we don't use proprammable servos there is no issue, hopefully I don't have one ;o) only simple digitals, and I have already a betafpv superP, but in any case channel 14 is not so easy to use on this receiver, then I can still use it safely. By the way I found this is a very good receiver.
sorry i don't understand ! is the ER6GV affected or not (sorry my english is not good that why i prefer to ask)
ER6GV uses GPIO1 so it is impacted. Look in RX \ Vario 2400.json for the pwm_outputs - pin 1 is there
I'm having this issue on my analog for HK Frenzy plane. Couple time actually.
Well, now you have the workaround.
@@RCVideoReviews Yup hope we can confirm other that it isn't just digital programable servos. But seem not much reporting?
This isn't the first elrs hardware issue. Early tx modules had some issues too
One clarification though, this isn't really considered a design flaw. In order for certain features to be able to work, they need to use the PWM pins as serial communication channels. So I'm not sure what the programming fix will be; however, I think it starts with Theta and perhaps a shift to ESP32s instead of ESP8525s where more pins are available and more options are available to the developers.
I got the jta slick and used the er4 with agf BO5CLS servos and dam is it snappy. Bwtween the high speed of the servos and the low latency of elrs its without a doubt the most responsive plane I have. Definitely going with elrs rx with my planes in the future. Hopefully they come out with some higher channel counts. Like 8 10 or 12 ch recievers would be cool
RM ER8 is 8 channel PWM. BetaFPV SuperP is 14ch. I'm all ELRS on fixed wing too.
Do you know if the er4 has this issue?
@@Euwanh85 I don't have this issue with the er4 and agf servos mentioned above
@@jakeclauson9863 I tested and it worked well
Excelente trabajo 👌.
Actualmente cuantas marcas hay de receptores PWM ELRS?
Sinceramente solo conocía los de Radiomaster y ahora que veo por tu vídeo los de happymodel
Creo que solo son BetaFPV, Happymodel, Matek y Radiomaster.
@@RCVideoReviews Muchísimas gracias por la información. Ahora me pongo manos a la obra para buscar información.
Por qué prefieres utilizar en tus aviones este sistema de módulo PWM/ELRS sobre ejemplo el módulo multiprotocolo de Radiomaster?
Cuáles son esas características que te han animado a utilizarlos?
Por qué si ELRS ofrece más confiabilidad otras marcas como Spektrum o futaba que son maraca TOP no lo utilizan? En teoría es mucho mejor que sus protocolos DSMX, FASST.
Spektrum y otros están invertidos en sus propios protocolos. Uso ELRS por varias razones:
1) La modulación LoRa tiene un rango excepcional. Usando poca potencia, puede volar por millas. Usando una potencia más alta (pero aún dentro de las limitaciones de ISM de la Parte 15), el enlace de control tiene un alcance que supera a todos los protocolos convencionales.
2) Flexibilidad: un protocolo admite CRSF para modelos con FC/FBL y ahora Gyros. Admite SBUS para otros Gyros/FC que no admiten CRSF. Admite PWM para modelos con conexiones directas desde RX a servos.
3) Precio: uso receptores de $ 13.99 y tengo un enlace de RF asombrosamente confiable con todos mis aviones.
No tengo ningún uso para los receptores de $ 70 que hacen menos. Te animo a unirte a nuestra discordia para seguir conversando.
@@RCVideoReviews Ohhhh... Valla veo por donde vas y realmente todo parece mejor que utilizar esas marcas caras por menos que ELRS.
Tengo que confesar que hay puntos que mencionas y no entiendo jaja, pero comprendo la idea.
Muchísimas gracias por tomarte el tiempo para ayudarme, lo aprecio mucho.
Otro aspecto que me da extrema confianza en ELRS es verte utilizar aviones carisimo (por lo menos para mí). Para que te hagas una idea de los equipos que abundan en Cuba, pues aún en se vuela gran parte con radios de cristales, utilizamos casi siempre los servos futaba s3003 estándar para nosotros en aviones construídos por nosostros mismos en otras maderas que no son balsa. Pero esto es una parte linda del hobby.
Ya estoy en el Discord, últimamente lo reviso mucho y estoy algo al tanto de los chat, pero me es un poco complicado por el idioma.
Saludos desde Cuba 🇨🇺
Does it affect the Matek CRFS to PWM boards?
To my knowledge it only impacts PWM receivers.
@@RCVideoReviews PWM receivers you mean?
Yes, receivers. I do not know if the converters experience the same issue.
@@RCVideoReviews They probably don't since Tx & Rx use a separate UART IIRC
Without actually testing, I usually hedge.
Great troubleshooting job John, thank you a lot! Fotios
You're welcome.
I just stick with radiomaster. Had a matek take down a $500 model when it failed. Servos. Eh. I’ll stick with ProModeler, MKS, Emax, & some old Airtronics, Futaba & Hitec.
I agree with you I’m sticking with crossfire never fails
@@gotoroger I like ELRS myself, but anything with *real* FHSS and LORA is a winning combination.
@@Toysrme i’ve been flying crossfire on all my planes and quad coppers for a long time never had a problem ever.. I just bought the ELRS system haven’t tried yet. Now I’m kinda afraid i’m not saying it’s not a good system but.
I have ELRS on every plane. Wouldn’t trade it for another system at this point.
@@RCVideoReviews maybe I’ll give it a shot I’m not saying elrs is bad I just never try it
Thank you for your special service
You're welcome.
What does PWM stand for.
Thanks for the video! Very helpful.
You're welcome.
Great info! You are the guru! Thnx!
You are so welcome!
Not saying anything bad about happymodel but both epw5 and epw6 have had problems left and right.
I have EPW6 in a lot of models and they've been reliable for me.
Thank god I got the betafpv superp with 14 channels to choose from😆😆😆😆
I crashed nitro plane with ER4 and JX PDI 6221 with this issue
ruh roh
here we go again with the rx issues
RX issues? All of my ELRS RXs have been stunningly good.
Now I get Spektrum....😁
Spekjunk is just as bad
You'd have to pry ELRS from my cold dead hands.
They can fix it by not using those chips LOL Unless it’s the only plumbing
Thanks for this awesome analysis.
Jacob Scherer did a latency test with a radiomaster er3c-i and showed that for this reciever PWM channels 1 and 2 show garbage during boot:
ruclips.net/video/OfxvGxojPYc/видео.html
Can you say why also channel 1 shows garbage in this case?
Thanks alot.
sheeesh, I'm going back to spektrum NOT
Right, it's a constrained scenario with an relatively easy workaround.
Stop using those digital programmable servos and you solved your issue. Why go through all the song and dance?
Oh I dunno, aside from the fact you can change these values:
• Dead zone
• Pulse input range
• Max current
• Output range
• Soft start
• Current protection
• Neutral range
• PWM Center
Pair that with the fact these servos support 8.4v input and provide Torque/Speed @ 8.4V of 22kg/.07 60 deg compared to Hitec 225MG analogs which caps at 6v and max torque of 4.8kg and .11 60 deg
Why would I settle for that on a plane that can push these higher end servos to their limits? Finally, the subject plane was an RxR of which I already KNOW ExtremeFlight has sold out and will continue to fly off the shelves--Why not look at the root cause?
So don't buy a top shelf RxR with SUPERB servos pre-installed, or worse, remove the pre-installed servos and replace them with lower performing analog servos
OR
Move ONE WIRE from PWM2 to PWM6
Yeah, real song and dance. Tough choice.
@@RCVideoReviews Maybe for someone that requires all those features then changing PWM2 to 6 is not a bad work around. However I am not sure how many people that uses ExpressLRS wants or needs those programmable features. Personally I like ExpressLRS because of simplicity, light weight, small foot print and good range. So if I have to sacrifice by using some other brand or type of servos no deal breaker. Especially when you are talking about the ER6GV. That is a receiver best suited for a glider with a narrow fuselage. No need for a 22kg/.07 servo.
Your context is obviously different than the context in which this situation arose. The blanket statement "use different servos" is not an appropriate answer just because your use case doesn't require the same servo capabilities as the one in this situation.
There are different needs for different craft. In this case, the craft benefits greatly from the servos used. The RF tech should not be a deciding factor in that choice.
can I use yappu telemetry with these receivers? thanks