[sdiy] STM32 vs WM8731

[Julian Schmidt]

you could also have a look at oliviers elements repository.
There you'll find schematics and code for a module that uses the stm32f4 
and the WM codec.
https://github.com/pichenettes/eurorack/tree/master/elements

or at erics codec board
http://ebrombaugh.studionebula.com/synth/stm32f4_codec_v2/index.html



On 17.02.2016 09:42, Rob Spencer wrote:
> Thanks for the advice everyone. I tried to initiate a write to 0x00 
> and still no luck.
>
> Here’s the setup I’m using at the moment:
>
> https://www.dropbox.com/s/27qcwate85vuofd/2016-02-17%2008.35.57.jpg?dl=0
>
> It’s a homebrew Morpho shield that fits onto the top of the Nucleo:
>
> https://www.dropbox.com/s/fq1bthc74bthbct/2016-02-17%2008.36.09.jpg?dl=0
>
> I’m going to do some checks around the board based on the suggestions 
> below.
>
> One quick question I’ve got is around the clock speed for the I2S MCK. 
> In the I2S standard it mentions 2.5MHk, however STM32CubeMX wants at 
> least 48MHz to run at 48KHz, even more if its running at 96KHz. Does 
> that sound about right? It feels a bit high and if it is I’m really 
> into new territory here in terms of PCB layout, but that’s the fun 
> part, right?
>
> Many thanks again
>
> Rob Spencer
> gmsn.co.uk
> 07590 267835
>
>
>
>
> On 16/02/2016 15:17, "Synth-diy on behalf of Eric Brombaugh" 
> <synth-diy-bounces at dropmix.xs4all.nl 
> <mailto:synth-diy-bounces at dropmix.xs4all.nl> on behalf of 
> ebrombaugh1 at cox.net <mailto:ebrombaugh1 at cox.net>> wrote:
>
>     I've brought up a *lot* of systems with the WM8731 over the years.
>     Getting the I2C control interface working can be a pain.
>
>     Your HAL I2C command looks right at first glance and the schematic
>     seems
>     OK too, so it's probably something else. One thing that you haven't
>     described is what the physical construction approach is. On the
>     WM8731,
>     you'll notice that the MCLK input pin is right next to the I2C SCL
>     pin -
>     I've found that the I2C SCL input is *extremely* sensitive to
>     crosstalk
>     from the MCLK signal and if you built this on a solderless
>     breadboard,
>     or with flying wires from the MCU to codec then you can easily
>     swamp it
>     out to the point where you get no ACKs.
>
>     If you have a scope with high impedance probes, look at the SCL input
>     pin - if you see MCLK there at a low level, it's a good bet your
>     WM8731
>     can't hear the I2C bus due to the crosstalk. Reroute the signals
>     or put
>     a simple RC lowpass filter on the MCLK to mitigate that.
>
>     Eric
>
>
>     On 02/16/2016 01:37 AM, Rob wrote:
>
>         Just continuing on the STM32 discussions…
>
>         I’ve been trying to get a Nucleo-F411RE talking to a WM8731,
>         but not
>         having much luck getting it to communicate over I2C
>
>         I send the following from the STM32:
>
>                           WM8731Status[0] =
>         HAL_I2C_Master_Transmit(&hi2c1, 0x34,
>         WM8731PowerOn1, 1, 10000);
>
>         But I don’t get an Ack from the WM8731:
>
>         https://www.dropbox.com/s/yhen98n17pyrqgr/Screenshot%202016-02-16%2008.22.15.png?dl=0
>
>         Here’s the schematic for the WM8731 setup:
>
>         https://www.dropbox.com/s/e6fkerkmf95ldzf/Screenshot%202016-02-16%2008.20.29.png?dl=0
>
>         I’m pretty sure everything on the STM32 side is setup
>         correctly, and I’m
>         working on the assumption that there’s not a lot to do with
>         the WM8731.
>         Once all the power is connected and the I2C mode and address
>         pins are
>         set low it should just receive I2C messages. I think the issue
>         might be
>         around the address, but I’ve tried all combinations I can
>         think of.
>
>         Any help would be much appreciated as my wife is getting tired
>         of me
>         shouting at the darn thing!
>
>         Many thanks in advance
>
>         Rob
>
>         gmsn.co.uk
>
>
>
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