Thanks Rick! I'm going to show a custom switch in an upcoming video. I've done a lot of these for clients with really aggresive board size but I have not adapted one of those to a project I can show publicly. That's coming up soon though.
@@Zachariah-Peterson Hi Zachariah, apologies I don't know the lead time for the videos Altium produce, but has this custom switch video been uploaded anywhere yet? Seems exceptionally interesting!
Basically yes. We matched the pinout being used on one group of switches I did in the past, although you could redo the pinout to just match a standard Ethernet cable, or you can look at the Ethernet-to-RS-232 interface for guidance on pinout. Regardless of how you do the pinout, you only need two signals and the rest may be shunted to ground, if left floating they can radiate or receive but you have to be careful with that on long cable runs where one ground is floating with respect to another, Howard Johnson states on his SigCon site about the types of voltage offsets you can see between equipment (he states 10 V on his site) when there are ground offsets between different pieces of equipment, even if they are technically on the same mains circuit.
So much talking (the video starts at 4:00) but nothing was said other than "line driver" for arguably the most important piece? You used a SN75C3221PWR which is RS-232. Why use that versus say RS-485 with a MAX14787E?
Thanks, Zach for an instructive project. I agree that in this little convertor board, there is no earth connection, but the chassis pin of the other end of the ethernet cable that is connected to the switch could be connected to the earth. In this case, you connect directly the chassis ground of the whole system to the signal ground. Right?
Generally you should not tie a system ground to a chassis whenever there will be a risk that a return current can flow into the chassis. A chassis should not be used to carry a return current for EMC reasons. I have discussed this in another video on grounding and on mounting holes.
I am guessing the pinout on the RJ45 was fixed by some standard. The way the twisted pairs are routed effectively puts TX and RX on a twisted pair (ok, one on each but the other side of each pair is tied together). Not the best to reduce crosstalk. Pin 8 is more than just chassis ground, it is the logic ground for TX and RX as well.
The way the pinout is done is it puts the RX and TX close together on the board but the TX would have its own pair (1,2). You could tie those to GND on the module but then you are bridging grounds between your floating module and what might also be a floating GND in your networking unit (switch, etc.).
Great and useful project, but the name is very misleading - this has nothing to do with Ethernet. As @Nick Alexeev also said, changing the title to "RS-232 over RJ-45" will avoid some really crazy confusion.
You're right it was not supposed to be interpreted as "sending data from a serial bitstream over an Ethernet link". It's just UART (RS-232) interfaced over RJ-45 to match the implementation in some modern networking equipment. First time I had to do this kind of thing was with a startup, they wanted to match what Cisco started.
Can't wait!
Custom Ethernet switch design, love the pace and complexity of your videos!
Thanks Rick! I'm going to show a custom switch in an upcoming video. I've done a lot of these for clients with really aggresive board size but I have not adapted one of those to a project I can show publicly. That's coming up soon though.
@@Zachariah-Peterson Awesome, thanks for sharing!
@@Zachariah-Peterson Hi Zachariah, apologies I don't know the lead time for the videos Altium produce, but has this custom switch video been uploaded anywhere yet? Seems exceptionally interesting!
i cant find the switch project
Are possible make a connection with websocket to send messenge json file to android applications ?
Please talk to us about C12 on this board. That's an RF shunt, right?
Basically yes. We matched the pinout being used on one group of switches I did in the past, although you could redo the pinout to just match a standard Ethernet cable, or you can look at the Ethernet-to-RS-232 interface for guidance on pinout. Regardless of how you do the pinout, you only need two signals and the rest may be shunted to ground, if left floating they can radiate or receive but you have to be careful with that on long cable runs where one ground is floating with respect to another, Howard Johnson states on his SigCon site about the types of voltage offsets you can see between equipment (he states 10 V on his site) when there are ground offsets between different pieces of equipment, even if they are technically on the same mains circuit.
So much talking (the video starts at 4:00) but nothing was said other than "line driver" for arguably the most important piece? You used a SN75C3221PWR which is RS-232. Why use that versus say RS-485 with a MAX14787E?
Thanks, Zach for an instructive project. I agree that in this little convertor board, there is no earth connection, but the chassis pin of the other end of the ethernet cable that is connected to the switch could be connected to the earth. In this case, you connect directly the chassis ground of the whole system to the signal ground. Right?
Generally you should not tie a system ground to a chassis whenever there will be a risk that a return current can flow into the chassis. A chassis should not be used to carry a return current for EMC reasons. I have discussed this in another video on grounding and on mounting holes.
where is the promissed switch design video?😢
I am guessing the pinout on the RJ45 was fixed by some standard. The way the twisted pairs are routed effectively puts TX and RX on a twisted pair (ok, one on each but the other side of each pair is tied together). Not the best to reduce crosstalk. Pin 8 is more than just chassis ground, it is the logic ground for TX and RX as well.
The way the pinout is done is it puts the RX and TX close together on the board but the TX would have its own pair (1,2). You could tie those to GND on the module but then you are bridging grounds between your floating module and what might also be a floating GND in your networking unit (switch, etc.).
Why is USB needed here?
USB- UART, с какого-то прошлого проекта
@@tonyivy6319 , из проекта USB uart в проект Ethernet uart даже контур платы не подойдёт :) Какой смысл это как основу использовать ?
Inaccurate title for this video. The title should be "RS-232 over RJ-45 cable". There's no Ethernet in this video.
Yes there was some confusion with "serial over Ethernet" vs. "RS-232 over Ethernet connector" during editorial process, fix is in though.
Great and useful project, but the name is very misleading - this has nothing to do with Ethernet. As @Nick Alexeev also said, changing the title to "RS-232 over RJ-45" will avoid some really crazy confusion.
You're right it was not supposed to be interpreted as "sending data from a serial bitstream over an Ethernet link". It's just UART (RS-232) interfaced over RJ-45 to match the implementation in some modern networking equipment. First time I had to do this kind of thing was with a startup, they wanted to match what Cisco started.
I guess, stm32f7 with external phy or wiz7000 all in one
STM32F107 + LAN8720A :)