A project log for Multichannel Audio DSP Field Mixer Recorder

USBmidi, bluetooth app controll 8 chan portable DSP mixer.balanced audio IO,phantom power,flexible routing,ISO recording. networked Timecode

ben bilesben biles 02/28/2019 at 03:320 Comments

So the new board is working great and is stable ONCE IT STARTS !!!

But sometimes I need to make 3 or 4 resets to make the DAC lock onto the

DSP TDM output. At least I think thats the issue.

I have set the DAC clock to devide/2 , its running a 24.576mhz clock , but

I still need to /2 on in the DSP sigma studio settings to make the outputs work.

I made one obvious mistake on this latest board that was no issue since all the stm32f7 pins are broken out anyway. the spi sclk pin was still hooked up to spi2 where i switch everything to spi1. It could have still worked anyway perhaps if I'd just fired up spi2 sck gpio but I just plugged in a jumper wire into PA5 instead :)

the SPI port is using DMA so you need to use the DMA enabled pins for corresponding Alternate Function mapping.

My next error was the lack of TP's (test points) on the main TDM IO lines between either the ARM or the ADC DAC module boards. I can easily sneak in wires into the module board connectors but it will be harder to find TP's between the DSP and the ARM SAI ports. I deliberately didn't break out these lines to connectors since they will be relatively high speed. TDM8. I'll probebly find some via's if I really need to test these lines, but they are very short traces so they should just work.

There is no micro NOISE and nearly no bluetooth noise detectable even though i'm running the analogue off the digi power supply for now. all good ! This will go away 100% with a bit of shield and separate Power from analogue.

My next analouge board will have the dual rail power board slotted in like the preamps. I will also separate Phantom power , digi power and dualrail power as I seam to becoming a fan of modular plugin board design ! 

I've changed all the GPIO pins for uSD cards SAI ports etc in the firmware and this begins to work. I want to dual record to the uSD cards for redundancy in recording.

Now I need work on the recorder app file manager and bluetooth app for the recorder player. I have the wav file names of recorded files coming back to the BT app but its very clunky !

and find out whats going on with the DAC /2 not working and check through the ADAU1467 startup procedure to make sure I got that correct.