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new digital board arived :)

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 09/04/2018 at 08:030 Comments

Just got my new 4 layer board and 2 layer daughter cards. I need to make a new analogue IO board to but will have to use

my old one for now.

I decided to be brave and add the stm32f7 micro and programmer on the underside. I also included DRAM !

I'm not sure I'll use the JTAG or not. I have a micro usb port hooked up to an STM style serial programmer.

There should be 2 x uSD cards slots but I didn't appear to have DMA capable pins left on the micro to accommodate that.

I have broken all the spare micro pins out so maybe i will find a way to make the redundant file storage work.

I didn't bother with a usb host controller to simplify the design.

I kept all the parts to 0603 and avoided BGA

The DSP and QSPI flash are QFN style though.

I'm using a 10 channel fan out clock buffer U5 for 24.576mhz. the ARM micro can generate this but using the external clock

I can hopefully keep clock jitter to a minimum.

As you can probably see in pic there a ton of vias ! The DRAM chip is under the micro and there seams to be no good

way to wire up RAM to a stm32f7 !

Each trace has only 1 via from micro to dram. Its not running to fast so hopefully it will work.

The Daughter boards are spit plane and analogue power / GND will come from the analogue connector IO side

I don't really need 32 channels of balanced analogue audio IO !

I may well make BUSIO_B a digital IO board !

I was thinking of AES3 or maybe even something like DANTE

There's a bluetooth module header and SPI header that runs to the analogue board for digital gain etc.

I've ordered the parts. the NOR flash qspi chip was near impossible to get , I got some samples on way. 20 week lead time!

Might need to try and change that part to something less difficult to obtain on the next revision.

I should have enough power for all the IC's including the digital side of the ADC's and DAC's.

Lets hope I haven't made to many mistakes and its usable :) I'll be happy to bin the old proto board that didn't even have

power or ground planes :)

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