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I'm building a custom headunit for my motorcycle using the Arduino platform. I wanted to try it as the modular nature of the board and shields looked very versatile. While there does seem to be plenty of documentation on how to use a single shield on a board, there seems to be very scant documentation on how to use multiple shields on a single board.

I tested the Adafruit Music Maker and the TFT separately. My code for each works as expected. However, when I stack them, I run into the issue of how to call each shield to perform it's task.

The issue is the shield pinouts. The MM uses the ICSP to communicate with the board so all I need are:

  • MCS pin - set to pin D7
  • DCS pin - set to pin D6
  • CCS pin - set to pin D4
  • DREQ pin - set to pin D3 (also a Mega interrupt pin)

By itself, the MM shield works correctly using these pins, but in order for the TFT to work, the TFT needs pins D2 to D9 to send LCD data. That means I need to reroute D3,4,6, & 7 for the MM so the signals to the TFT are not interfering on those pins.

I noticed those pins have corresponding hole-throughs on the board.

Adafruit MM

Can I use these hole-throughs to redirect the pins to other digital pins on the Mega?

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Yes, you can. However you will need to isolate them from the existing pins.

If you flip the shield over you should see a set of bridged solder jumpers:

enter image description here

You will need to take a small, sharp, craft knife (or something similar) and cut the little track that joins the pads together. If the time ever comes that you want to "undo" that cutting you can just bridge the pads with solder.

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  • Excellent! Let me try that... Jan 14 at 15:57
  • That worked! Now I can print to the TFT while the MM is playing. Thanks Majenko! Jan 15 at 9:46

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