[sdiy] STM32 (or other) audio DSP learning recommendations

[Eric Brombaugh]

On 07/06/2018 07:34 AM, Scott Gravenhorst wrote:
> 
> One of the odd things about the WM8731 is the "SPI compatible" control port.  I would have
> expected I2c, but that is not the case. 

The WM8731 can work in either I2C or SPI modes, depending on the state 
of the MODE pin (21). When it's held at logic 0 the device uses I2C 
protocol and when it's pulled up to logic 1 then it operates in SPI 
mode. I used I2C mode in my STM32F4 Codec board and it works fine.

One thing to be very careful of is that Wolfson in their wisdom located 
the serial clock pin and the main oscillator input pin right next to 
each other. This makes the serial clock extremely susceptible to 
interference from the main oscillator when building prototypes on 
solderless breadboads or with flying hookup wire. If you find you can't 
talk to the device double check that the serial clock line is not being 
contaminated.

Eric