Quote:
Originally Posted by Waldy
After replacing the display or with someone else's image recorded on the µSD card, you can try this method to change the vcom value.
1. Make sure that you have firmware 4.38.23171 installed on your Kobo Nia, if not, update it.
2. Now install the firmware kobo-nia-temporary-update-4.41.23145.zip on top of 4.38.23171.
In this firmware, I simply changed the drivers so that it would install on Kobo Nia and it would be possible
change vcom value.
3. Change vcom values following these instructions: https://www.ifixit.com/Guide/How+to+...Display/170983
4. After the change, do a hard reset using the button or turning on devmode.
Developer options - Factory reset your eReader.
5. Update to the latest firmware (currently 4.38.23171).
I tested this on Kobo Nia, but do so at your own risk. |
update:I was wrong vcom can be changed with this method! so the kernel does have this ability after all??? but it may not fix ur fading issue
Dont bother with this it didnt work; I have both a Rev A and Rev C Nia motherboard, I was able to update to 4.41 on both, although I now know the A and C have different kernels and waveforms despite the motherboards being able to recieve the same firmware upgrades. Switching sd cardsbetween them results in failure to boot on either. something is different when it comes out the factorysoftware wise, Szybet on github made mention of something similar of kernel sources being outdated for Rev C Nia. the firmware says it has changed the vcom but the display fading remains, I thought maybe it was because I damaged the motherboard because I only have one screen but 2 boards, one of which has the correct vcom already, after changing the vcom on the one that was correct it didnt even have a fading issue, meaning that it was never changed. It was 2.57 and 2.52; I changed 2.57 to 2.52 and 2.52 to 2.57. Also in the update folder you dont need the upgrade folder or even the drivers folder, since we already have those by being on 4.38? Was that a precaution? So the lesson is that the vcom change requires the correct kernel or something uboot?
Also be careful, I read dust can cause artefacts on e ink screen, after doing many board changes to make sure I wasnt just doing something incorrectly, theres an exposed area of the display when you remove the pcb and some dust accumulated, no issue at first but after I wiped with a damp cloth now it seems artefacts like grainy appears after a while. Sigh. Wait im not sure if im crazy or if im staring too closely... it seems like i cant see it anymore bc it seems to be permanently in the grainy state, in eed anew screen to compare with... hmm seems to be gone, it was similar to the fading
Thus the only way to truly use a new screen is request a display with the same vcom, or find an sd card image with the required vcom, I wonder what the distribution of vcom values is like, if its a normal distribution with a peak in the median then finding a correct one wont be too hard but still needs many ppl to image their sd cards and note the vcom on the display
4.38.23171 Rev C waveform 320_R387_AD6F21
4.38.23171 Rev A waveform 320_R390_AD4321
edit:hmm so waveform is unique to each panel... i now know waveform is stored at sector 14336 thanks to postmarketos kobo nia wiki page. copying from that sector until the first partition results in a change of waveform, however copying from sector zero to first partiion leads to change in vcom as well. i wonder if changing vcom is possible after all? i need to test by copying the waveform to my rev a mb