I really like this neat little unit. It's small, cheap and have excellent performance per consumed energy ratio even by todays standards. I want to build audio delivery solution based on PCM5102A Hi-Fi chip using Omega's I2S output.
This is ongoing projest and more details will be added in project log.
Today i finally booked myself to test oled screen.
Initially i soldered out headers for both SPI and I2C screens to test them both.
First discovery - I've soldered out SPI pins wrong, MISO and MOSI are switched places, but what is more important, with oled display connected to SPI bus it won't boot. Kind of a bummer.
According to docs GPIO7 and GPIO8 being SPI CLK and SPI MOSI must be left floating at boot, and clearly that's not the case with screen connected. Of course I'd be able to make it work with buffer IC between omega and screen, but since i was ready to have it only for free, I'm dropping SPI idea alltogether,
As for I2C screen - it works perfectly normal. Once again in the docs there is a great info how to jump start it and even nice command line tool is bundled in.
So there it is, i'm keeping I2C version of the screen for next revision and SPI has to go.
Revision B just came and i had a chance to solder it and do a quick test.
Compared to a previous one, there are few key changes
- I completely changed power source part. rev A was planned to be used in combination with 2.5 inch HDD and therefore i estimated it to use at least 5W. For this one i decided to keep it simple and replaced it with simple AMS1117 linear reg for digital part, and LP2992 low noise linear reg for digital part.
- I made it smaller, to be more specific I tried to make it raspberry pi case compatible. This is yet to test since I'm still waitinf for case to be delivered.
- I moved all the parts to front side to simplify assembly and replaced barrel caps with pcb mounts for the same reason.
- I removed some unused pereferial, instead broke out SPI and I2C headers to plug in OLED screens. Just because why not, it is free:) Yet to test.
- Added 4 gpio leds, again why not.
In terms of software so far no change, all works same way as before. Key part is audio DAC, and it works like a charm. So far just an headphones audio test and i'm quite happy with the result, however more test to come.
As for OLED screen - placement could be better, and testing to do.
Overall, quite pleased with the result, no major flows, however probably one more revision to come to fix minor issues.
Presense of this device doesn't imply that souncard is working, it will bang I2S pins even if they hang in the air. But to have the sound device listed is a good sign.
Next you test audio with any audio file or stream, I used my local stream here
High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2and3
version 1.22.3; written and copyright by Michael Hipp and others
free software (LGPL) without any warranty but with best wishes
Playing MPEG stream 1 of 1: fg ...
ICY-NAME: Fabio & Grooverider
MPEG 1.0 layer III, 128 kbit/s, 44100 Hz joint-stereo
ICY-META: StreamTitle='ÿþR - ÿþF';
Voila, we have a sound!
- I want to build latest firmware version with I2S support enabled
- I found board hanging on wifi initialisation. I soldered 100uF cap to power pins directly and the issue went away. Now i need to adjust PCB design to have decoupling caps closer to Onion board.
- Today found an article on separating digital and analog grounds, need to try that as well:)