Electronics > Microcontrollers

Driving a round AMOLED display

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Nominal Animal:
If you want to set your sights a bit lower, BuyDisplay.com aka EastRising has a pretty nice 1.28" 240×240 IPS round display with a GC9A01 controller and documentation (module, panel, panel).  It's rather similar to ILI and SD display controllers, so you shouldn't have any issues getting these to work.

I like BuyDisplay/EastRising, because the display modules are not expensive, they have the documentation on the product page, and have real-world videos of their products on their Youtube channel.

JPortici:
I can vouch for that display.
Pretty good, though i'd prefer it came with parallel interface, or at least a way  to probe the TE pin

SiliconWizard:

--- Quote from: Nominal Animal on February 11, 2021, 05:20:42 pm ---If you want to set your sights a bit lower, BuyDisplay.com aka EastRising has a pretty nice 1.28" 240×240 IPS round display with a GC9A01 controller and documentation (module, panel, panel).  It's rather similar to ILI and SD display controllers, so you shouldn't have any issues getting these to work.

I like BuyDisplay/EastRising, because the display modules are not expensive, they have the documentation on the product page, and have real-world videos of their products on their Youtube channel.

--- End quote ---

Yes, this display is not quite as nice, not AMOLED, lower res. But I have good experience with EastRising. The displays are good, and support is too. I once requested tech support for one of their OLED displays, and got a pretty timely answer.

bzlabs:

--- Quote from: Minyiky on February 09, 2021, 06:58:47 am ---I am looking to use a round AMOLED display with an ESP32 and have found 2 basic options (with a 3rd that is slightly different). I have found some displays based on an RM69330 display driver (such as this: https://www.alibaba.com/product-detail/1-39-inch-ips-454x454-rohs_62286293416.html) which seems to support MIPI and SPI, which seems to be backed up by the vague pinouts I have seen that have SPI labled pins. The other lookks to be driven by an RM69080 display driver that only appears to have MIPI pinouts and so wouldn't be suitable to be used with an ESP32. As another option there is something like this larger screen that appears to support SPI/RGB: https://www.szmaclight.com/product/round-lcd-display-2-1-tft-480x480-RGB.html

One problem I am running into is that I cannot find a datasheet for the RM69330, or any written drivers, which would make it very difficult to use the screen.

--- End quote ---

Apologies for reviving an old thread, but I've recently been going down this same path, as you can find those AMOLED screens for < $20 shipped, which would make them amazing for ESP32 projects if possible to connect and drive them.

I've had a little luck tracking down some info so I figured I'd share what I've found so far in case it's useful to others.

I got a RM69330 "User Guide" from messaging a seller on Ali and asking for datasheets, though it seems to be focused on manufacturers of displays as the "user" rather than application engineers. As far as I can tell it's mainly documentation of a bunch of registers (that I believe are one-time-programmable?) for things like panel configuration, charge pump settings, etc. Generally it does not seem useful to me, as I assume the drivers should already have these values programmed appropriately by the panel manufacturer.

Of more interest though, I noticed that Ambiq had published release notes for their SDK indicating they added driver support for RM69330, which led me to finding this driver implementation for Ambiq MCUs which uses SPI. There's a lot of potentially good stuff there (and in the .h file) including code that initializes the driver IC, and there's good documentation about how to configure SPI. I'm not familiar with Ambiq's SDK, but if I'm reading it correctly, I think I'm seeing several different configurations for either single SPI (SerialCE0DisplayMSPICfg) or quad SPI (QuadCE0DisplayMSPICfg). One potential concern I see is that their driver sets the SPI clock to 48MHz, which is a bit daunting to me in terms of data integrity if I throw together a cheap test PCB, but since it's SPI, it would hopefully be possible to just slow that down to something more hobbyist friendly while initially trying to get it to work.

There seem to be multiple similar models of 1.39" AMOLED panels based on the RM69330 driver available, so for clarity, I'm focusing on the panel that's marketed as a Huawei GT2 46mm smart watch screen replacement, which came marked "FP10128WA" but I believe also can be found as "wb014znm-t00-6dp0". These panels seem pretty readily available, and also come bonded to glass/bezel and includes a touch digitizer, which would be useful in the future if I can ever get the display working. One difference I've seen on spec sheets for similar displays is the connector. Some datasheets I've come across seem to indicate a YXT-BB1F connector with a 0.4mm pitch, but the GT2 46mm display connector appears to be 0.35mm pitch using calipers, and if the spec sheet I found is the correct one, that would be a BM28U-24DP_2-0.35V(86)_2D_SPE connector. I've got the mating connector on the way from digikey, and will update when I find out whether it's correct or not.

For that specific model of display, and again assuming I'm looking at the correct spec sheet, a few things stood out to me:

* VDDIO is listed as 1.8V typical, 1.95V max, so would need high speed level shifters to try to interface with ESP32, but based on the reference circuit, nothing else besides some decoupling caps and a pullup resistor would be needed
* Battery voltage is 2.9V min, 3.7V typical, and 4.8V max, so theoretically possible to share a 3.3V supply with the MCU, but would NOT be ok with 5V supply
* "Driver IC RAM Size" is specified as "Full RAM or 1/2 RAM" which seems to indicate that the RM69330 has a framebuffer which makes the idea of driving it with an ESP32 seem more plausible
Still seems like an uphill battle to get this working without additional documentation, but I will try to keep making progress. If the connector I ordered works, my next step will probably be to spin a quick breakout PCB for the connector and level shifters based on the pinout in the spec sheet I found... If the connector doesn't work it's back to scouring the internet for more clues...

olibali:
Hello!

I am in the process of making a CircuitPython driver for an OLED display called: "PV13904PY24G".
It also uses RM69330 as driver chip. I only use the SPI interface.

It is not yet done but I need to step away from it and maybe someone can continue or learn from what i already have.

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