Audio playback

[patc]

For room measurement first I connected a microphone to a soundcard in a PC running Windows but I would prefer to use the Parallella instead.

Working on the feasibility phase I selected the PCM3052A (which beside the ADC integrates a mic pre-amp with balanced inputs and SPDIF output as well) and added a 8-bit MCU for the settings (I2C). The module runs on a 9V battery and I did a quick test of a spectrum analysis with the PC.

I also ordered this DIY kit which looks significantly better and I want the compare the performances of both modules when doing room measurements (I intend to make a PCB with proper shielding for the PCM3052 because the current module is for feasibility only).

Time to get back to a bit of VHDL...

[aolofsson]

Having a Paralellella test your setup would certainly be poetic

btw. I have been meaning to ask you..do you have some pictures of your mods to the top side of the Paralellla board? What components did you take off and how did you couple the board to the heatsink. Did you use thermal pads to height match?

Andreas

[patc]

[aolofsson]

Thanks for the great explanation. Really enjoying watching you build this!

For the cooling, you might want to do dothermal coupling for some of the smaller chips as well to increase longevity. With the amount of metal you have connected to the board, it's probably not an issue...

In order of importance:
zynq (a must)
epiphany (definitely recommended)
hdmi (would be nice)
9307 (would be nice)
9305 (would be nice)
usb (would be nice)

Andreas

[9600]

That's some pretty resourceful thermal management!

I'm working towards building a Parallella-based tablet, thinking about how best to conduct heat away, and was leaning towards having a U shaped piece of copper bonded to the case and gently pressing down on the Zynq via thermal gap filler. I guess this could be neater / more compact if I removed Ethernet and USB, wiring the pads for the latter to a WLAN dongle. But then I'd prefer to not have to attack the board with a soldering iron.

Any reason you opted for a curved thin copper sheet and paste, instead of thermal gap filler?

Cheers,

Andrew

[greytery]

[patc]

[aolofsson]

Wow! Speechless. You are taking smaller, cheaper, faster (better) to a whole new level.
Cute dog! Looks like he approves
Andreas

[patc]

ADC#1 - PCM3052A
- started from a 9V battery case
- made a PCB fitting on top
- built the enclosure around the whole thing

next:
- use Mike Field's SPDIF input VHDL code to extract in the Parallella the audio data from the SPDIF stream outputted by the ADC module
- use the same VHDL code I wrote for playback but the other way around: while audio data fills a buffer, the other buffer is DMA'ed into DDR
- then Cortex-A9 writes DDR data to the SD card
- when measurement is completed, run DRC to generate the correction filters
- do the same with ADC#2 Cirrus Logic CS5361 and compare
- enjoy the music...


attached zip file contains:
- the Diptrace schematic + layout
- the 8-bit MCU C source code built with the Silicon Labs IDE coupled to SDCC (both free)

[9600]

I honestly wish I had the know-how to build projects like this! Once again, very cool indeed

It would be really great if you could publish the project to GitHub or similar. That would make it a lot easier for people to find it, learn from it and reuse etc.

Cheers,

Andrew