I have investigated using the internal ADC on the ESP8266 for audio recording. My requirements are low - 8KHz sampling (ideally at 16b but because of what I say next, that's a moot point). It seems that even with WiFi disabled etc, I can't get analog_adc to run faster than 5KHz. So, i'm moving to an SPI solution, described here: https://github.com/sven337/jeenode/blob ... t/xmit.ino using this chip: http://www.esp8266-projects.com/2015/04 ... p8266.html
I want to record the audio to SPI flash (using SPIFFS) and it can happen when WiFi isn't connected if that helps performance. I've successfully written audio to SPI on other platforms at similar or higher bit rates without an issue.
Will SPIFFS handle a datarate of 8KHz 16 bit along with the simultaneous audio sampling?
Does anyone have any advice on the best way to do it? I'm assuming timer based, with a couple of 1K buffers, writing flip/flop to the SPI. Can the SPI write be DMAed, for example, so that it doesn't impact on the audio sampling?