Dig-Octa Brainboard-32-8L “Microphone Mod”

This article voids warranty in any way, shape or form! Please only perform modifications if you accept this risk!

Some people have asked if they can hook up a microphone to the Dig-Octa Brainboard-32-8L. With the current versions of the boards this is not possible by default since literally *all* of the GPIO pins of the ESP32 are used.

The board by itself already has 2 button inputs and I2C exposed on terminals, but if you need more GPIO pins for other purposes (all pins have HW pull-up/down attached, etc.) you can free up some with a little bodge work (at your own risk, voids warranty!)!

Option 1: Borrow pins from the MicroSD-card slot

The MicroSD-card on the board has 4x GPIO lines connected to it:

  • GPIO14
  • GPIO15
  • GPIO16
  • GPI36 (no output)

These can be “borrowed” from the MicroSD-card slot if you are not going to use that function. This will give you a few GPIO lines to play with to hook up other devices such as Analog or Digital Microphones.

To be able to use these lines and have fairly easy pads to solder onto the following can be done:

  • Remove SDcard slot with hot air
    • Maybe melt some low-melt solder into the joints first since everything is soldered with high-temp leadfree solder paste!
  • Remove Resistors tied to GPIO lines with hot air or iron

Once that is done, the pads of the MicroSD-card slot can be re-used for your own purposes and double as a fairly easy location to solder your wires! Please see the following picture for where the connections are:

Option 2: Borrow pins from the Ethernet function

Another option, if you want to keep MicroSD-card functionality is bodging wires directly to the ESP32-WROOM module on the board. As mentioned above, all pins are used though but what you can do is turn off the Ethernet function (remove the jumper on the board) and that fully disables Ethernet and all related hardware components, including pull-up or down resistors!

GPIOs used by Ethernet are:

  • GPIO17
  • GPIO18
  • GPIO19
  • GPIO21
  • GPIO22
  • GPIO23
  • GPIO25
  • GPIO26
  • GPIO27

Then you can solder wires directly to the ESP32-WROOM module (fairly easy with the castellated edges!) and use them for your own purposes! Again, be warned, this is very much for your own risk and voids any warranty! Please see the image below for the location of each of the GPIOs!