New QT-PY BFF: Sound support

[michaelmeissner]

On Sunday's Live from the Desk of Lady Ada, Lady Ada mentioned about designing new BFF boards. One thing that may be missing from the line up is the ability to play sound. I'm thinking in particular about cosplay setups where space is at a premium, and you want to some neopixels and maybe play some sounds.

Some of the QT PY boards can use the DAC (digital to analog converter) support in the chip feed into an amplifier and hooked up to a speaker (perhaps the Stemma Speaker, product id #3885).

But other boards don't have DAC support. I could imagine several different ways to provide sound support:

1) Have a BFF that does I2S, possibly along with amplification, and output to either a mono or stereo speakers. Here you likely need jumper pads to cover the different pinouts used by the RP2040, ESP32-*, etc. QT PY's. Possibly this might be a rework of the MAX98357A board (product #3006) for amplifier and mono speaker. Perhaps adding support for an optional MEMS microphone.

2) Have a BFF that can do pre-recorded sounds, such as a simplification of the Audio FX sound boards (product id #2220) with control being I2C from the QT PY (or maybe Serial using TX/RX). Whether the file system to hold the sounds is separate from the flash memory on the QT PY microprocessor or not is a design detail. I could see advantages to either method. If you have flash on the sound BFF, you would presumably need a USB connector to load the flash, or ways to transfer bits to the BFF sound flash. Or dispense with the flash and put a micro SD card reader that the device can use (similar to the DFRobot dfplayer).

3) For your typical cosplay project, you don't need crystal clear sound, and perhaps having a BFF that has the extra capacitors, and such needed to convert a normal PWM pin into an audio output, along with amplification. You could have jumper pads of whether to enable the capacitors or not, and what pin to use as PWM/DAC output.

[adafruit_support_mike]

I'll mention those to the products team.. thanks for the suggestions!

[adafruit2]

we have plans for a MAX98357A BFF - that's the best option that would be maximally-compatible except for the SAMD21 Qtpy - altho it would use A1 thru A3 since you need CLK/DAT/LR signals

[michaelmeissner]

That is good to hear about a MAX98357A BFF, though you always have the issue of what pins are used and do they conflict with other uses. Unlike the feather system, with QT PY, you don't expect to stack BFF's like you would with feather wings.

Of course, I could imagine a use for a QT PY with a BFF that combines the lipo, neopixel driver, and the MAX98357A BFF's that would fit nicely in a standard goggle eyepiece with a 1200mAh lipo battery in the other. I realize that the small area of the QT PY footprint means tradeoffs have to be made and it would be unlikely to have a combined unit.

Speaking of feather wings, it would be nice if there would be an analog of the prop-maker feather wing that uses the MAX98357A instead of a DAC. Most of the M0/M4 feathers seem to be out of stock.

[adafruit2]

an I2S propmaker is also on our list :) chips were hard to come by for a while but are sloooowly becoming more available