As explained @13:21 to add a bit of mechanical strength for the lead. If you mount the flex sensor on a surface and guide the flex through a hole, you want to have a bit of extra mechanical strength to prevent sharp folds that may (will...) damage the connections to the touch points. It's the easiest way to provide some form of a minimum bend radius
@@robinjansen51 Technically, the sensor is the part with the squiggly lines or the square touch surfaces so the ground plane is only on the traces towards the sensor. But yes, you are right. Adding a ground plane will increase the capacitance of the sensor itself, reducing the touch effect so adding a gound plane, or attaching the sensor on a metal surface, is not a good idea. In this case, the ground plane is only a small section on the lead and will not have that much effect.
Hi, I was trying to follow the tutorial to customize the sensor but got stuck at 10:53. The square I drew is not filled. I tried to enable the "show filled zone", tried different net designation, tried to connect the pad with vias. But non of the ways above make the copper pad fill. Do you have and idea about this?
Did you solve it ? You have to edit the pad and assign to it the net of the trace and via that connects to it. If for example the trace is called "signal1" you have to assign the specific copper area to signal 1 through the settings.
@@rockndancenroll Thanks for your reply. The pattern is still not filled even if I assigned net. I couldn't get any support on this issue from neither the Kicad forum nor the Bela. I think it is because the unconventional design patterns. So I switched to Altium designer. The pattern fills in that software
Hi how do I prevent the back off the touch pads acting as a sensor just want the front to be touch sensitive will a ground fill on the bottom layer do this?
Hi Billy, if you would like to create a PCB which is a combination of FR4 and flex substrate have a look at Rigid-Flex PCBs which combine the two in one design. There is more information here: www.pcbway.com/blog/News/What_is_Flex_PCB____An_Overview_of_Flex_and_Rigid_Flex_PCB.html
Hi Josue, these two pins are already connected together on the symbol and footprint of the connector so it is only necessary to connect to one of them and there will automatically be an electrical connection between the two. Make sure to route your connections to both though.
Thanks, happy to hear you enjoyed it! You can definitely use Trill Flex for these kind of experiments. You have 30 channels of capacitive touch at your disposal so you could even draw up a custom flex PCB with 15 variations of the interdigitated electrode design (presuming each one uses two channels). Just make sure the design ends in the ribbon cable like in the tutorial. You can then read from the Trill Flex board with a microcontroller of your choice or an embedded system like our Bela. Let me know if you have any other questions.
Would it be possible to create multiple strips/areas per unit? Ie, a 4x4 grid (16 channels), then 2 strips each 7 channels long. All on the same board? Thanks!
Sure, all the pads are independent. You can group them as you see fit as long as you interpret the readings appropriately on the host. You can use the CentroidDetection library for that.
they measure capacitance only. With the right geometry of pads you can get touch size which can work as a proxy for touch pressure in certain contexts.
Thanks, happy you enjoyed the tutorial! Regarding sensing through other materials, it is definitely possible to sense through thin layers of vinyl, acrylic or other non-conductive materials. Experimentation with different settings is key here. See here for some more information on materials which work and how to adjust the settings learn.bela.io/products/trill/integrating-trill-into-your-projects/#covering-trill-with-another-material
@@jaydenstrudwick4329 You're welcome! Moisture in general will definitely affect the reading you get as it conducts electricity. If the top of the sensor was wet then you might end up with sporadic readings as there will be many activation points. The plus side of this is that you can use water as an extension of the capacitive pad. This means that with our Trill Craft sensor you can attach the pad connection to a glass of water or something similar and detect when the water is touched.
Hi, when drawing the shape with the 'Add a Filled Zone' tool, it has no fill. it's only an outline. because of this, I cannot round the squares. Do you know why I have no fill ? How can I draw filled squares ?
@@chair_audio hi, thank you. it's not working. it has no effect... a window pops up called 'Fill All Zones', a time bar fills up but no changes... I wonder why...
Hi, Bela, It's a great video! Do you have an idea that how small of the sensor unit can be? Can I have smaller overall size with same amount of sensor units?
Hi Ziqi, thanks! The sensor units can be quite small, well less than the size of a fingertip. Smaller sensors won't produce quite as much signal and they won't sense through overlay materials as well, but they definitely work. For example, if you look at our designs for Trill Hex you'll see it uses a lot of very small interlocking diamond-shaped pads.
@@BelaPlatform Thank you for the prompt reply! I already made the order.(the one shipp to Gsinesville, FL) I will let you know if I have further questions!
13:04 Why are you adding a ground plane? And why is the ground plane above the traces?
As explained @13:21 to add a bit of mechanical strength for the lead.
If you mount the flex sensor on a surface and guide the flex through a hole, you want to have a bit of extra mechanical strength to prevent sharp folds that may (will...) damage the connections to the touch points. It's the easiest way to provide some form of a minimum bend radius
@@Rob_65 I thought it is not recommended to apply a groundplane to the rear of a sensor like this. Correct me if I’m wrong.
@@robinjansen51 Technically, the sensor is the part with the squiggly lines or the square touch surfaces so the ground plane is only on the traces towards the sensor.
But yes, you are right. Adding a ground plane will increase the capacitance of the sensor itself, reducing the touch effect so adding a gound plane, or attaching the sensor on a metal surface, is not a good idea. In this case, the ground plane is only a small section on the lead and will not have that much effect.
Hi, I was trying to follow the tutorial to customize the sensor but got stuck at 10:53. The square I drew is not filled. I tried to enable the "show filled zone", tried different net designation, tried to connect the pad with vias. But non of the ways above make the copper pad fill. Do you have and idea about this?
Did you solve it ?
You have to edit the pad and assign to it the net of the trace and via that connects to it.
If for example the trace is called "signal1" you have to assign the specific copper area to signal 1 through the settings.
@@rockndancenroll Thanks for your reply. The pattern is still not filled even if I assigned net. I couldn't get any support on this issue from neither the Kicad forum nor the Bela. I think it is because the unconventional design patterns. So I switched to Altium designer. The pattern fills in that software
is the touch wheel version available ?
Really nice tutorial! Thank you!
Hi how do I prevent the back off the touch pads acting as a sensor just want the front to be touch sensitive will a ground fill on the bottom layer do this?
Thank You, Great Tutorial!
Can the flex PCB go direct to a regular FR4 board or does KiCAd force you to use a connector?
Hi Billy, if you would like to create a PCB which is a combination of FR4 and flex substrate have a look at Rigid-Flex PCBs which combine the two in one design. There is more information here: www.pcbway.com/blog/News/What_is_Flex_PCB____An_Overview_of_Flex_and_Rigid_Flex_PCB.html
Is that possible to download this 5*6 touch pad kicad file directly
How can I associate the ground plane to pin 1 and pin 32 at the same time?
Hi Josue, these two pins are already connected together on the symbol and footprint of the connector so it is only necessary to connect to one of them and there will automatically be an electrical connection between the two. Make sure to route your connections to both though.
Awesome tutorial.
I just wanted customized interdigitated electrodes using flex PCB for research purposes. Is this recommended for that?
Thanks, happy to hear you enjoyed it! You can definitely use Trill Flex for these kind of experiments. You have 30 channels of capacitive touch at your disposal so you could even draw up a custom flex PCB with 15 variations of the interdigitated electrode design (presuming each one uses two channels). Just make sure the design ends in the ribbon cable like in the tutorial. You can then read from the Trill Flex board with a microcontroller of your choice or an embedded system like our Bela. Let me know if you have any other questions.
@@BelaPlatform Glad to hear that. Thanks for quick reply
Would it be possible to create multiple strips/areas per unit?
Ie, a 4x4 grid (16 channels), then 2 strips each 7 channels long. All on the same board?
Thanks!
Sure, all the pads are independent. You can group them as you see fit as long as you interpret the readings appropriately on the host. You can use the CentroidDetection library for that.
are these sensors touch and pressure responsive?
they measure capacitance only. With the right geometry of pads you can get touch size which can work as a proxy for touch pressure in certain contexts.
That was an awesome tutorial! Have you investigated placing the Flex Board behind a material (e.g. plastic), would this affect the reading?
Thanks, happy you enjoyed the tutorial! Regarding sensing through other materials, it is definitely possible to sense through thin layers of vinyl, acrylic or other non-conductive materials. Experimentation with different settings is key here. See here for some more information on materials which work and how to adjust the settings learn.bela.io/products/trill/integrating-trill-into-your-projects/#covering-trill-with-another-material
@@BelaPlatform Thanks for the reply! When wet, damp or raining would this affect the readability?
@@jaydenstrudwick4329 You're welcome! Moisture in general will definitely affect the reading you get as it conducts electricity. If the top of the sensor was wet then you might end up with sporadic readings as there will be many activation points. The plus side of this is that you can use water as an extension of the capacitive pad. This means that with our Trill Craft sensor you can attach the pad connection to a glass of water or something similar and detect when the water is touched.
Nice video, thanks :)
Hi, when drawing the shape with the 'Add a Filled Zone' tool, it has no fill. it's only an outline. because of this, I cannot round the squares. Do you know why I have no fill ? How can I draw filled squares ?
To (re)- fill zones, press "b"
@@chair_audio hi, thank you. it's not working. it has no effect... a window pops up called 'Fill All Zones', a time bar fills up but no changes... I wonder why...
Easier to import a bitmap than use that kicad polygon editor to draw copper shapes.
Hi, Bela, It's a great video! Do you have an idea that how small of the sensor unit can be? Can I have smaller overall size with same amount of sensor units?
Hi Ziqi, thanks! The sensor units can be quite small, well less than the size of a fingertip. Smaller sensors won't produce quite as much signal and they won't sense through overlay materials as well, but they definitely work. For example, if you look at our designs for Trill Hex you'll see it uses a lot of very small interlocking diamond-shaped pads.
@@BelaPlatform Thank you for the prompt reply! I already made the order.(the one shipp to Gsinesville, FL) I will let you know if I have further questions!
OMG! What a class!
In your next video will you pronounce kiwi?