[sdiy] ARM Cortex M4F chips with CODEC interfaces & DIY-friendly packages

[Eric Brombaugh]

On 09/16/2014 07:12 AM, nvawter wrote:
> 3. Eric Brombaugh made a nice, little stm32f4 board with a 16-bit codec
> and SD card slot.
> It had some small issue with the SD card in the first rev, but the codec
> worked great
> and I don't know if he took it any farther
>

I've worked all the bugs out of my STM32F4 + Codec board and the design 
materials are available here:

http://ebrombaugh.studionebula.com/synth/stm32f4_codec_v2/index.html

A quick summary of features:

* STM32F405 MCU (168MHz clock, 1MB flash, 192kB SRAM, ARM Cortex M4F w/ FPU)
* 128x160 color LCD display
* 4 pots for parameter adjustment
* rotary encoder w/ button for user interfaces
* SDIO-based micro SD card interface
* USB OTG (device/host) interface
* Wolfson WM8731 16-bit stereo codec with line in/out, headphone and mic.

I've used this MCU in a number of synth products recently and it's an 
extremely capable part - the FPU allows a great deal of flexibility when 
working on complex DSP algorithms without worrying too much about fixed 
point scaling issues that often come up when optimizing code.

I'd also suggest looking at the somewhat smaller, slower and cheaper 
STM32F3xx family of parts. They're available in 48LQFP packages and and 
also provide a Cortex M4F with floating point - 72MHz max clock, but 
somewhat cheaper, and the F373 variant includes 3 16-bit ADCs that will 
operate up to 50kHz sample rates - great for audio. I've got a design 
for a breakout board using this chip which I have found very useful:

http://ebrombaugh.studionebula.com/embedded/stm32f373breakout/index.html

Eric