I recently added audio capture support to an Atomthreads-based product. I used a Texas Instruments audio codec, the TLV320ADC3101, for which I wrote a device driver from scratch for the Atomthreads real time operating system.
The ADC3101 contains an embedded programmable DSP called the “miniDSP”, which you can build your own firmware for and upload to the device at startup. One thing that is not entirely clear from the ADC3101 datasheet is whether one is actually required to create and upload firmware to the miniDSP or if it can be used without. From the datasheet we can read:
The fully programmable algorithms for the miniDSP must be loaded into the device after power up.
In fact it is not necessary to upload firmware to the miniDSP (unless you need the flexibility of writing your own processing blocks). The ADC3101 contains default processing blocks which can be found in the “ADC Decimation Filtering and Signal Processing” section of the datasheet, e.g. Filter A.
This means that one does not need to install TI’s PurePath Studio or write any custom miniDSP firmware, and can achieve a functioning audio device driver from the ADC3101 with relatively few instructions.