Author Topic: PiDSP - 24bit/196KHz DSP board for Raspberry Pi  (Read 545 times)

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Offline Pitrsek

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PiDSP - 24bit/196KHz DSP board for Raspberry Pi
« on: April 09, 2017, 06:29:14 AM »
Hi guys and gals,
I've been reading this forum(and watching Dave's vidos)for some time, today I've decided to join.
Coincidentally, today I've also migrated my hobby project to a github. So I tough I'll share it with you:
https://github.com/freeDSP/PiDSP
So if you feel like it, take a look, tell me what you think.

Thx for your feedback,
Pitrsek

 
 
The following users thanked this post: bobaruni

Offline Pitrsek

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Re: PiDSP - 24bit/196KHz DSP board for Raspberry Pi
« Reply #1 on: April 09, 2017, 07:47:22 PM »
Some pictures:
 

Offline Pitrsek

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5V buck fix
« Reply #2 on: April 15, 2017, 12:52:13 AM »
Fixing the stuff I missed on last revisions(there is a buglist on github)
One of the more shameful mistakes was thermal design of main 5V buck. It could not deliver 3A with temperatures I would consider reasonable.
I kinda did not pay enough attention to small print in the datasheet  |O. Go and take look at PCB that is used for specifying package thermal resistance, that PCB is bigger than you would expect... 
I sandwiched buck between edge of pcb and RPI connector. I missed my goal of 3A output by about half an amp. Also I did not verified used inductor beforehand, AC losses were way to high. So for next revision I've improved thermal design for buck and diode. Since I have a little more board estate I can go for a bigger inductor. Samples are on the way(WE 74437358047). And I'll test the inductor before  sending boards to production.

I've also discovered that I did not performed "remove unused pad shapes", so there was not really much copper in the ground plane in between RPI connector. That compromised heat transfer into the rest of the board. That is fixed now, so hopefully we'll get better cooling. I'll probably go for 35um copper thickness on next PCB as well - to see the effect of changes. As you can see the difference in web width is quite big - actually now its more than twice the original width.
 

Offline Pitrsek

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Re: PiDSP - 24bit/196KHz DSP board for Raspberry Pi
« Reply #3 on: April 18, 2017, 12:09:02 AM »
?Still some stuff to clean-up, but PCB is starting to look quite all-right  :)
 

Offline Pitrsek

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rotary encoder recommendation wanted
« Reply #4 on: April 20, 2017, 05:06:09 AM »
Hi,
I'm looking for a quality rotary encoder with switch, any recommendation? It's going to be used as front panel controls, so it will get decent amount of (ab)use.
Optical encoders seems to be a bit too expensive for my taste.
Also new inductors arrived today, I should have impedance measurements tomorrow.
 
EDIT:Found rotary encoder thread :) http://www.eevblog.com/forum/projects/decent-rotary-encoders/msg949756/#msg949756 
« Last Edit: April 20, 2017, 05:12:52 AM by Pitrsek »
 

Online bobaruni

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Re: PiDSP - 24bit/196KHz DSP board for Raspberry Pi
« Reply #5 on: Yesterday at 02:42:49 AM »
Well I think your part of it looks really nice, very nice board design too.
I'm using the same cheap ES9018 DAC board from Ebay and some parts of it are implemented badly and my board (not saying all sellers sell the same) had a lot of bugs with it that made it sound terrible.
Silly mistakes like regulator transistor PNP instead of NPN and inserted backwards and ES9018 running on 5V instead of 3.3V
The I/V leaves a lot to be desired as well but I have modified it to use a similar I/V to that on the ES9018 datasheet and it now sounds fantastic (no more clipping and clean transients).
« Last Edit: Yesterday at 02:50:02 AM by bobaruni »
 


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