I’ve done a lot of disassembly/reassembly on this thing in the last few months, most of it with it not in a working state, so not sure how recently any of these effects are.
I just got my RK3588 and set about installing it. The display isn’t showing anything, and that’s the issue I’m trying to figure out / diagnose.
i dont have any storage other than whats onboard the RK3588 a SD card flashed to the latest reform system image for it. there’s no ssd or nvme or wifi installed. (also no batteries and just running off the dc power if that matters)
In pursuit of that I flashed the keyboard and LPC up to the latest firmware, which is cool, but didn’t change anything.
Looking at S1 serial has been difficult. I haven’t be able to get my primary serial adapters (rpi debug probe and adafruit ft232h breakout) to get real logging out of it. listening with a saleae logic analyzer, it looks like its outputting serial at ~1.562 Mbaud, which is pretty fast!
with that able to decode some of the serial, it looks pretty standard. DDR timings and voltages, tries to boot from MMC1, knows its a reform, etc.
in all of this, the backlight for the display appears to be on, but nothing ever comes through. no bootsplash or text or anything.
my goal is to get it back into a nice daily driver with the rk3588, but first step might be how to figure out whats up with the serial speeds and then whether somehow i messed up the display or its just a software/firmware thing
There is a chance the display cables are not plugged in correctly or in the right orientation, maybe you can send a picture of your board showing how the cables are connected to the hdmi adapter and CPU module.
The hdmi adapter is plugged into the motherboard, and there should be a ribbon cable (in the right orientation) and the display cable (in the right orientation) connected to the adapter. The ribbon cable connects to the CPU module and should be connected to the module as well (in the right orientation )
According to the operator’s manual the RK3588 module serial ports run at 1500000 baud. I would double check here to see if you can get your ft232h breakout do talk to it. I am not sure if there are speed limitations on the breakout or if this is an appropriate UART to USB adaptor (should be 3.3v and not 5v).
Edit: I checked the adafruit website for the ft232h breakout and it doesn’t seem to be a UART adaptor, instead it provides other protocos via USB (?)
You might have better luck with an adaptor like this:
The FT232H is setup to work with 3.3V and 5V logic levels, so unless its using something exotic, i’d expect those to work. I think it’s UART of the primary uses of those chips https://ftdichip.com/wp-content/uploads/2020/07/DS_FT232H.pdf – and they should be able to go up to many Mbaud, but possibly the linux driver isn’t configuring it correctly above the usual speeds.
the pico debug probe doesn’t have a listed set of configurable baudrates, so i dont know what to expect there.
I’ll try to figure out how to set one of them to 1.5Mbaud – I don’t know why my initial tries weren’t working, but possibly the linux driver isn’t being clever about how its handling rounding.
I’m pretty certain the display is hooked up correctly but can provide shots of that soon.
I also have a pocket, so if its compatible, one thing i could do is try swapping the displays. i do think the display cable has been through a lot as i’ve disassembled/reassembled it a bunch in the past couple years. I also think i probably have a compatible display in a box in the basement somewhere i could try as well.
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