Installing Ubuntu 20.04 (Focal) with BSP uBoot with deep sleep and sound

[Syonyk]

Yeah, you need a UART to troubleshoot further, then.

The reason the light doesn't come on with nothing on the eMMC and no SD card is because the firmware (loaded from eMMC or SD card) is what turns that light on.

There's a tiny bit of boot ROM in the system that looks on the SPI (hazardous to mess with - quite the pain to recover if you screw it up), the eMMC, then the SD card for the firmware files at the proper offsets. That firmware handles turning on the LED, general system bringup, and booting from, by default, the SD card then the eMMC. If you've got a bad firmware on the eMMC, the system won't progress to booting from the SD card (until you turn the switch off).

Serial will illuminate the problem. You don't have a 3.3V TTL USB to serial adapter and a spare 3.5mm stereo cord laying around? That's what I built mine from...

[TDC_PBP]

Unfortunately I do not . Would it be worth it to reflash the EMMC just to generate the dmesg log file? It wouldn't be live like UART, but at least then I could see what the error was, right? Fair warning: I am really new to the world of log files and UART debugging.

[Syonyk]

Buy or build a proper adapter. Personally, I'd build an adapter as I've heard the Pine ones have some weird quirks to use, but... I also have a pile of TTL serial adapters laying around, and I've re-chipped most of them with proper FTDI chips.

[TDC_PBP]

What parts do I need to buy to build the adapter? I can probably find an aux cable to sacrifice, but I am really clueless on a) what parts to buy, and b) how to assemble the cable. If possible, could you link to the parts I will need on ebay US? Thanks!

[Syonyk]

I'll tell you what you need, but it's on you to find parts.

You'll need a USB to TTL serial adapter that handles 3.3V (you must make sure it's 3.3V or you'll fry the board - a lot of them default to 5V, some are 5V only), then a 3 ring 3.5mm stereo headphone jack. I think the 4 ring ones work too, but that's not what I had laying around.

There are a few writeups floating around on how to wire stuff, though the pinout is on the wiki as well.;

However, if your cable uses at all standard colors, you'll put (on the TTL serial adapter side):
- Braid to ground
- White to RX
- Red to TX (optional, if you're just pulling logs off, no need to connect this)

Serial configuration is 1500000 baud (1.5Mbaud), 8N1, and you'll need to flip the switch inside the laptop to make the headphone jack work as the UART. See the wiki.

[TDC_PBP]

Would this one work: https://www.ebay.com/itm/6-Pin-USB-2-0-t...0#rpdCntId? Also, what does the 3rd connection do (and why is it not necessary for pulling logs)?

[Syonyk]

I'm not a huge fan of the CH340G, but as long as it does 1.5Mbaud, should be fine.

The third connection is the transmit line. From your remote machine to the device on the serial link... if all you want to do is receive from the remote device, you don't need the transmit line connected.

If you're not comfortable with serial links and such, this may not be the task for you.

[TDC_PBP]

Would this one be better? https://www.ebay.com/itm/CP2102-FTDI-USB...SwOFFeNHTO It has an FTDI chip and comes with wires.

[Syonyk]

Dude. As long as it's 3.3V, supported by your OS, and handles 1.5Mbaud, it'll work. Pick one. No idea how you set that one to 3.3V, some have jumpers, some require soldering.

[rbma]

And you unxz'd the image before copying it to the eMMC?

What does lsblk show on your eMMC after you've flashed the image and rebooted on the SD card?

After I flash the image, I can't boot from anything and just sit there with a yellow light forever. When I plugged the EMMC into my computer it looked like it had been flashed correctly   . I am currently downloading a new image to see if the one I used the first few times was corrupt (I currently have flashed Q4OS to the EMMC just so I could boot again). I did unxz the file and DD the .img file, as well as use Etcher. On a side note, it seems Q4OS won't boot from SD even after flashing BSP uboot   .

FWIW, I had the exact same experience trying to use ayufan's Ubuntu Focal image.  I could boot from SD, but dd to the emmc would not work.  

I ended up using Fedora, but I can't get audio working at all.