Chris BurtonThe "Chinese market" Raspberry Pi CM0 has made it to the UK 🥳 .
Still seems a strange product, even the URL on the box ( https://raspberrypi.com/products/cm0-dev ) doesn't work 🙄 .
In free air the #CM0 looks to hold it's own thermally and doesn't throttle running stress, stuffed in a cardboard box it happily throttled as expected.
Continuing my CM0 fun from last night where I removed the module from the dev board, soldered it to my carrier, reflashed 64-bit Lite RPiOS and it didn't boot, no LED, nothing. Checked the schematic, PCB for shorts, voltages, etc. and couldn't find anything so took it off and put it back on the official dev board where it also no longer worked so I figured I'd killed it.
Another one arrived today and it looks like I've somehow got rpi-imager into a state where it writes, verifies and configures OK whilst shafting it enough not to boot 🤦 .
The rpi-imager problem was a red herring, after switching to dd I still can't get a [non-mangled] CM0 dev board to boot.
With the CM0 dev board on the left I can enable RPIBOOT, apply power, run rpiboot, write an image/sync, remove power, disable RPIBOOT, apply power, LED turns on after a couple of seconds and it boots from the eMMC.
But following the same steps on the other board when powering up after disabling RPIBOOT the LED never turns on (it was on whilst writing the image) and it doesn't boot. Even writing the image from the working CM0 doesn't boot (reading back after a failed boot still has the original sha256sum).
Anyone have any pointers?
Nothing is shown on a monitor when it should be booting (no rainbow).
It reminded me of a problem I had with a custom CM3 carrier where I didn't have HDMI SDA/SCL pullups but adding "hdmi_ignore_hotplug=1" didn't help here.
I'm not sure what the proper way to enable UART debug is these days but using.
enable_uart=1
uart_2ndstage=1
start_debug=1
I see output on the working CM0 but again nothing at all on the troublesome board.
I received another batch of 10 CM0 last week. Combining the results from all batches I'm seeing a 25% "failure to boot from eMMC" rate which is less than ideal 😠.
It took a while (thanks to UPS) but my "CM0 NANO Single-Board Computer" has arrived in the UK (from Digikey https://www.digikey.co.uk/en/product-highlight/e/edatec/cm0-nano-single-board-computer ).
Nico