BluePill support and other STM32F1 (cortex-m3) boards

[marcel-licence]

I would like to add support for the BluePill as well. Unfortunately I couldn't use the I2S code from arduino. I is not compileable. It looks like there is no I2s supported on the board. I could imagine that there is a DAC available which could be driven using DMA. If someone has any idea please let me know. I would be happy to integrate the support.

[BrianHarper]

Maybe something like the MCP4922 although it's only 12bit, but it is SPI and has 2 channels.
Another thought was PWM but using 2 pins like the Mozzi Hifi mode. I have never tried this so couldn't say how it sounds.
Just a couple of thoughts for you..