Direct GPIO connection of Adafruit Standalone Toggle Capacitive Touch Breakout


#1

Hello there! I’ve got the Adafruit Standalone Toggle Capacitive Touch Sensor Breakout from Pimoroni and was wondering if I really need the 10k resistor that shows up in the adafruit guide to connect this (and a Momentary type one) directly to a Raspberry Pi:

https://learn.adafruit.com/capacitive-touch-sensors-on-the-raspberry-pi/wiring

Thanks!


#2

It looks like its a pull down resistor? Its just connected to ground. I don’t think anything bad will happen if you leave it out? Other than your touch breakout maybe not working as desired. How good are your soldering skills? If you cut the leads back on the resister and tack it to the ground pin and that other pin on the breakout, it should simplify the wiring to the Pi’s GPIO.


#3

Thank you, Kerry, great tip. My soldering skills are very very basic.

Since it won’t blow up anything, I’ll try it as soon as I can with and without the resistor and will post the results here.


#4

So, I did the tests and it seems to work the same way with and without the 10k resistor suggested for the [out] pin to GPIO 23 connection.


#5

Yeah, I’m not really sure why its there? Somebody thought it was needed or it wouldn’t be there? No mention of why its there either?
Looking at the code I don’t see anything to set (enable) the GPIO built in pull up down resistor on the Pi.
It would look something like this.

GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.IN, pull_up_down = GPIO.PUD_UP)

I’m guessing thats because they used

PIO.setmode(GPIO.BCM)
padPin = 23
GPIO.setup(padPin, GPIO.IN)

If weird things start happening you may want to consider adding it back in some how


#6

Thanks! I plan on adding it anyway, as soon as I solder all the bits.

I’ll leave you a sample of the no resistor test with manual holding all the wires to have the breakout connected to a pi zero w with a speaker pHAT. Adding link for sound :)


#7

I would have put the header on the breakout on the other side. Or maybe have used a 90 degree header so everything was on the same plain, all nice an flat, if you know what I mean. Your wires would be pointing down, not out the front. Not a criticism, just an observation.
Another way to do it is to snip the female connector off of one end of the jumpers. Strip the end and tin it. Then solder that right to the breakout with no header at all. Just throwing ideas out there. ;)


#8

All criticism is welcome! As well as all observations, of course :)

I haven’t yet soldered the header on the breakout as I still lack a definitive design for the project enclosure. I used a non-soldering, temporary, solution to hold the jumper wires that involved stacking male breadboard jumper wires on unused female jumper terminals with the breakout in between. I grew up really enjoying Lego so I find it hard to have non removable fittings :)

Great tips! I think I’m going with wire connected directly to the breakout, as you also suggest.

Thanks again!


#9

Ah, OK, you were thinking ahead. Well done.

Enclosures for what your building can be a challenge. You really have to be creative sometimes. Please post pictures when your done. It’s nice to see what other come up with.