Pico Audio + Readpi NFC - how to connect?

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1

Hello! First up, I’m a relatively newbie to the electrical rather than software side of all this, so apologies if a dumb question!

I have the ReadPi NFC board with Pico W - see ReadPi - An RFID/NFC Reader Powered with Raspberry Pi Pico W - SB Components Ltd.

I’d like to connect the Pimoroni Pico Audio pack at Pico Audio Pack (Line-Out and Headphone Amp).

Obviously the Readpi doesn’t have soldered headers, but it does appear to have all the GPIO pins ready for soldering.

Is it possible to connect the 2? I realise that may be a very dumb question - TIA!

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There are two aspects: physical and electrical connections.

From the physical side the answer is no, because the Audio Pack has two 20 pin sockets. Now you could imagine to solder pin-headers onto the Pico W of your NFC-reader, but that is not possible, since the Pico W is soldered flat onto the support PCB. So what you could do is solder wires directly to the Pico W, but that is not without challenges.

From the electrical side of things: again no. How could you find out? You have to download the schematic of both devices and check which pins are in use. The Audio Pack uses GP9-GP11 and GP22. And the NFC device uses even more pins (and all of the ones that the Audio Pack needs).

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Hey @bablokb,

Thanks for the reply! I had idiotically assumed the GP headers were interchangeable in code, appreciate the detailed explanation.

At the risk of pushing my luck: do you have any suggestions of how I might get half-decent quality sound out of the ReadPi device linked? I’ve got the ReadPi schematic at GitHub - sbcshop/ReadPi_NFC_Software: ReadPi 13.56 MHz frequency based NFC Reader/Writer powered by Raspberry Pi Pico W unit. This github provides getting started guide and other working details for ReadPi NFC version. and can see it leaves open GP0-3, GP6, GP7 and GP28, alongside GND and 3.3/5V. Would something like this - Adafruit Mono 2.5W Class D Audio Amplifier - PAM8302 - work?

4

Yes, I used a PAM8302 before together with a Pico. See GitHub - bablokb/christmas-box: A Christmas-box with sound and display. You need a PWM capable pin for that, but almost all the pins of the Pico support PWM, so this should work.

“Half-decent quality sound” heavily depends on the speaker. The one I use in the above project is definitely not good (far too small), but I had to make compromises.

5

This is incredibly helpful, thank you. In this picture I can see you’ve soldered little header pins to specific GPIO pins to use the Dupont cables - I’m not sure what phrase to use to search for these, what are the little solderable bits called?

My project is pretty simple - play audio files off the SD card when a given NFC tag is touched, think this may just do the job.

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These header pins are called header pins. You will have to solder them to the throughholes left and/or right of the Pico-W. You can find them here in the shop (or everywhere else, just make sure you buy the 2.54mm spacing variant). Break Away Headers - Straight