The DSP PCB board arrived!

[paulca]

Got my DSP "dev" board through from PCBWay today.

One botch so far.  A track swap.   Fixed now and nicely hidden under the MCU.

I've not tested the other two headers but the main optical in works and both DAC outs work.  MCU is happy.  2 separate EQs, one per output, 5 peak bands each.

It's a start.  So much further to go on the software and UI side, but I couldn't stand it being on breadboards any more!

Need to investigate a power supply filter for it.  It's silent running on my Tenma bench supply but not while on a shared DC rail from a buck converter it isn't.  Anyway, the power supply on this version was an after thought to take 5V instead of 3.3 and reg it down locally.  Power supply design comes later

I'll get round to testing the other two headers tomorrow.

[paulca]

I had all the toys out to play building it!  Figured I might as well put the old monitor up on the scope.  I'm actually hoping on putting it, or a smaller lighter screen on an arm so it can be in front of me.

[paulca]

Would you believe I killed it.  10 hours maybe 12.

Damn tenma power supply defaulted to 12.60V and 3 Amps and I hit "LOAD ON" before checking.

Now.  I installed a voltage regulator for the specific purposes of stopping that from happening.  The board run on 5V and drops it to 3.3V itself with an AS1117.

The AS1117 supports -20V to 20V, however mine came off a chinese regulator module for a breadboard.  So it might not be a genuine instance.

Well, whatever, now it only puts out 2.3V.

At least it served a purpose.  It took the 12V and cooked itself and not the rest of the board. 

It is now, once again, running fine just running off the STLink PSU until I swap that regulator out. 

[bobbydazzler]

If you use mlcc's for the 1117 you need to add some esr in the range of 0.1-10ohms to the mlcc.  Inrush current can easily cause the mlcc to rise to 2x your input voltage if you have no esr.