Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

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Sure10101
 
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Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

I want to design a basic touch sensor system . What parts would I need to do this . - Power supply ? - Adafruit 2900 - MPR121 - Relay - . This is to activate an automatic door system . Insulated push plate to operate door system . How do I connect the MPR121 to the relay ? . Common / Normally Open going closed upon activation .

Thanks .

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

You'll need a microcontroller board to read touches from the MPR121, and control a relay. A QtPy (probably the RP2040 model) would do the job nicely and you can use a STEMMA QT cable to connect it to the MPT121. What relay you use depends on how much current it needs to switch for the door system.

If you use CircuitPython on the QtPy RP2040 you can dispense with the MPR121 since the QtPy's GPIO pins are capacitive touch capable via the touchio module.

Dave

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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dave , thanks for the reply . So the parts I would need are as follows , please correct me if I am wrong . I am totally new to this . I have to use a 24vdc - 5vdc reducer as the existing control panel output is 24vdc . The relay contacts are clean contacts which will give the door system an activation signal when the contacts close . No current volt free .
1) 24vdc-5vdc reducer
2) RP2040
3) STEMMA QT cable
4) Power relay featherwing
5) What's the touchio module .

Would I have to do any coding as I wouldn't have a clue .

Thanks Shaun

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

touchio is a CircuitPython module that supports capacitive touch use of pins. Since thej hardware supports touch, you should be able to do it in C++/Arduino as well.

You d0on't need the STEMMA-QT cable if you use a QtPy pin for the touch input (thus not using the MPR121).

Yes, you would have to do coding. Not a great deal, but some. I suggest you do more research before diving in.

If you want to use the relay featherwing, you'll be better of using a Feather board rather than the QtPy. Feather RP2040 maybe, as it also has the same touch capable inputs.

Dave

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Sure10101
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dave , I have been watching you on YouTube about circuit python and how to switch on the ports required A0 - A3 for the capacitive touch . I think I have that part worked out , looks pretty straight forward . Is there a way of linking the touch to the feather relay so when you touch A0 , A1 , A2 , A3 the relay goes Normally Closed and reverts back to Normaly Open when no touch ? How would I get the power to the boards , plug in or solder onto pins 3.3v/GND then push the feather boards onto each other ? I could draw you a schematic of what I am trying to achieve if that would help ?

Thanks

Shaun

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

You need to write code to activate the relay when touch is detected on A0-A3 and deactivate it when there are no touches.

With the Feather you can use a battery or power it through USB.

You would stack the boards using headers. See https://learn.adafruit.com/adafruit-pow ... g/overview and https://learn.adafruit.com/adafruit-feather-rp2040-pico. If you want to avoid having to solder the touc sensor wiring to the feather pins you could use https://www.adafruit.com/product/2926, but you would need to use stacking headers on the feather (https://www.adafruit.com/product/2830) to connect to the terminal block board below it and the relay board above it.

There;s no real schematic needed: put the boards together, connect the door system to the relay and the touch sensors to the feather.

Dave

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Sure10101
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dave
I will be powering the boards from a 24vdc-3.3vdc voltage reducer . The power is coming from the existing 24vdc control panel from the automatic door system . So a cable will be needed . Is it a JST plug ? I take it you can code when the touch is detected the red led lights up ?
Shaun

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

Why convert to 3.3v? The Feather has a 3.3v regulator to convert the USB 5v. It's better to do that.

You can code pretty much whatever you want. That shouldn't be a problem.

Dave

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Sure10101
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dave , I think this will do , it's from Amazon cto convert 24vdc to USB 5vdc . Youmile 5PCS DC-DC USB Buck Converter Step-Down Module 6-32V 12V 24V to 5V QC 3.0 Charging Module Voltage Regulator Power Supply Module with 24AWG Wire .
https://www.amazon.co.uk/Youmile-Conver ... 48&sr=8-15 .
I will order a small USB - USB to link the converter to the feather board .
I think that's it .
Could you check out the link I sent to make sure .
I appreciate your help
Shaun
Attachments
USB - USB Cable.jpg
USB - USB Cable.jpg (12.99 KiB) Viewed 211 times
24vdc - USB 5vdc converter.jpg
24vdc - USB 5vdc converter.jpg (45.28 KiB) Viewed 211 times

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

If you use the Feather RP2040 you'll need a USB-A to USB-C cable.

Those modules should work. Plenty of output current capacity.

Dave

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Sure10101
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dave , thanks . Shaun

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Sure10101
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dan , I have all my components feather RP2040 , feather non latching relay and feather terminal block breakout . I am trying to write the code for the following to work with a feather non latching relay . Having a bit of trouble , could you assist please if possible ?
Will these pins work . I want to use pins a0 , a1 , a2 , a3 . When either one is touched they operate the feather non latching relay normally closed when touched - normally open when not touched . I will solder a link from the D13 to the link pin hole and then a cable to signal hole on the relay .
Are the pins I have selected correct ?
Any chance you could help me with the program code to make it work ?
I'm using Mu and have downloaded circuitpython to the RP2040 already .
Thanks Shaun .

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

I'm not quite sure what you mean by "I will solder a link from the D13 to the link pin hole". Other than that it seems good.

Dave

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Sure10101
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by Sure10101 »

Hi Dave , I don't know where to start . Do you know how to get the touchio working so when it is touched on pins A0-A3 it switches the non latching feather relay ? I thought you had to solder a cable onto the signal hole and solder the other end to another pin so the relay closes on touch . I assumed the link signal - D13 . I must have got it wrong . Any chance you could write me a small program to get the board when touched it to close the relay . I've been trying but no luck yet .
Thanks
Shaun

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dastels
 
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Re: Adafruit MPR121 12-Key Capacitive Touch Sensor Gator Breakout

Post by dastels »

The Feather reads the touch inputs on A0-A3 and when it detects one it activates the relay, and if it doesn't detect any it deactivates the relay. It sounds like that's what you have in mind.

There are plenty of guides that make use of capacitive touch. You use a digital output pin (D13) to control the relay.

What language are you programming in?

Dave

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