Thank you for your reply!!!
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I actually may have found the error as I was powering the IC with IOVCC = 3.3V to allow the reset signal to be 3.3V also. This worked fine for ILI9881 as it had a max IOVCC = 3.3V.
Now I found that ST7703 has a max IOVCC = 2.0V. So maybe I fried both of the two display samples I have Image may be NSFW.
Clik here to view.
Strange though that I can still write/read registers from ST7703, but I guess a part of the IC circuit could still be fried from the overvoltage.
Now I'm waiting for new samples of the ST7703 based display to see if it works with IOVCC = 1.8V. I'm curious to know though if the IC can accept 3.3V on reset without breaking. Otherwise I guess I need to logic shift the signal.
Yes I thought so too, I was just puzzled about the timing specification of the backligt in the datasheet. I tried replicating the exact timing of the power on sequence, including the backlight timing, but it didn't make any difference.The backlight is almost always powered external, not by the display controller. Generally the connections are "anode" and "cathode", ie directly on to the LED chains.
It is indeed very frustrating, especially as this is the second time I had to this with the same display. Thought my time off from doing MIPI DSI would have lasted a bit longer Image may be NSFW.Unfortunately debugging displays is generally a lot of looking at black screens and guessing what might be wrong. Information from vendors is frequently incorrect.
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This would be interesting to look into!In one case we resorted to taking the HDMI to MIPI bridge board that the vendor also sold, and decoding the MIPI signals that it used to initialise the display. That only vaguely matched the data we'd been given, but replicate that in the kernel driver and it worked fine. Decoding MIPI LP comms is relatively simple (it only uses data lane 0 and at a few 10's MHz), and if you're lucky your scope may have an option for decoding it.
I actually may have found the error as I was powering the IC with IOVCC = 3.3V to allow the reset signal to be 3.3V also. This worked fine for ILI9881 as it had a max IOVCC = 3.3V.
Now I found that ST7703 has a max IOVCC = 2.0V. So maybe I fried both of the two display samples I have Image may be NSFW.
Clik here to view.
Strange though that I can still write/read registers from ST7703, but I guess a part of the IC circuit could still be fried from the overvoltage.
Now I'm waiting for new samples of the ST7703 based display to see if it works with IOVCC = 1.8V. I'm curious to know though if the IC can accept 3.3V on reset without breaking. Otherwise I guess I need to logic shift the signal.
Statistics: Posted by badebold — Mon Jul 22, 2024 2:04 pm
