OLED panel / possible failure modes? - Page 1
Forum section: electronics / projects

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 12, 2020, 06:00:41 pm
content: I've had a Waveshare OLED module (https://www.waveshare.com/wiki/1.5inch_OLED_Module) in a drawer that I never used and decided to test it as a demo for the RISC-V core I'm working on. I'm using it in SPI mode. I've read the SSD1327 datasheet thoroughly, used the init sequence provided in Waveshare's example code, looked at a few projects implementing drivers for it too, tried a few variations of the controller parameters... Of course I checked and double checked that what I was sending through SPI was correct (with a logic analyzer). It definitely is.But... I can't get it to display a single pixel. It remains black. To further troubleshoot the issue, I measured the current drawn by the module, and it is definitely consistent with the init parameters I try AND the data I send to the display RAM. I even tried the "ALL ON" display mode (which is supposed to light up ALL pixels regardless of the RAM content), and the current draw is definitely consistent with what I should get if the display actually worked (~100 mA @ 3.3 V). Then in normal mode, depending on the RAM content, the current draw is also perfectly consistent, but the display remains all black. I tried various "contrast" parameters as well (which sets the internal current), to no avail (but the current draw still varies with it, although I was expecting more variation... so that may be a hint as to was could be wrong.)So, it kinda looks like the panel is borked in some way... but I'm wondering what could explain the power consumption. How can the panel draw (approx.) the same power as if it was actually lighting up the pixels, but all pixels remain off? Could that mean that all individual pixels are internally shorted (could be)? If so, how could that happen? (There is absolutely no sign of external damage to the panel, and I had never used it before.)

author: Miyuki
author_rank: Frequent Contributor
timestamp: December 12, 2020, 06:20:08 pm
content: Sounds like classic ESD damage to the controller

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 12, 2020, 06:48:19 pm
content: Although I can't inspect what really happens, the controller at least seems to interpret the commands properly, so if the OLED panel itself is fine, but there is ESD damage to the controller IC, that would probably not be on the "digital" side, but more in the output stage (interfacing to the OLED module), which, given that it's not directly accessible, would likely have happened during production. Of course the module has a "PASS" sticker on it... but I have no clue whether those are really tested or if the PASS status is just from visual inspection...

author: amyk
author_rank: Super Contributor
timestamp: December 13, 2020, 10:13:44 pm
content: Given that datasheet is from 2009, how old is the display? I wonder if it has died from the dreaded moisture ingress problem that has plagued OLEDs since the beginning:https://www.eevblog.com/forum/projects/oled-character-displays-dead-in-storage-or-something-else/https://www.eevblog.com/forum/projects/oled-storage-lifetime/

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 13, 2020, 10:28:44 pm
content: The module itself is still a current product at Waveshare, but I have no clue how old my module was. I bought it like 2 years ago, and it was stored in a dry place. But it could have been stored for years before that, I don't know, and worse than this, maybe the OLED panels that are used for those modules are very old stock. (Bought it off eBay IIRC...)Out of curiosity, do you think there is any way I can tear down the panel or something, so I can maybe see what happened? (Meanwhile, I have used a TFT SPI display instead, and it works fine...)