By now everyone with the slightest interest in Raspberry Pi stuff will know about the new kit released by the MagPi in collaboration with Google and available with the number 57 of the magazine. The AIY Project Kit is offered with the MagPi at the usual price of the magazine on its own. Quite amazing but not a surprise from a magazine that managed to give a computer as a freeby in 2015 and in fact still gives one for free when you subscribe for a year.
When I got the board I didn’t notice at first. Amongst other pads on which you are supposed to solder various bit and pieces, there was room for a second screw terminal. Could this be for an additional audio module?
If you read on the silk screen of the board it very much says left and right 🙂
A bit more digging quickly for AKKBDQ brought me to Adafruit MAX98357 I2S Class-D Mono Amp which uses the same chip. By all mean Adafruit isn’t the only one using that type of chip. Pimoroni has two boards with the same chip, the Speaker pHAT and pHAT BEAT.
The chip in question is the MAX98357 as you might have guessed from the Adafruit product and it is a PCM Input Class D Audio Power Amplifier.
The specs of this Amp are quite decent especially for the size of it and are very well indicated for applications like the AIY Project Kit. It works over I2S which is also the same bus used by the microphones in the same kit.
Reading further in the datasheet you find that this chips can be used in pairs to provide stereo audio. The acute observer will already know or have noticed that this is what the pHAT BEAT already implements such design.
Looking at the AIY Project Kit a part from the screw terminal for the Right channel you can also see JP4. This seems to indicate that you can indeed enable a second channel and have stereo audio as you would with the pHAT DAC.
This eventually takes me to JP6. It is fairly visible in the picture above that several of the pads on JP6 go to the MAX98357 already on board. My guess is then that there will/might be an add on card to be soldered on JP6 and possibly the two pads just behind the un-populated ones for the additional screw terminal.
Could it be that things have been designed after all with the Adafruit module in mind?
After all, it could be such a nice fit that it would be a shame if that wasn’t intentional!
