Has anyone been successful in getting a STM32F7 series to work with Raspberry Pi 7" touchscreen?

[CLued.1916]

STM32F769I-DISCO offers a part to get it compatible with the RP MIPI DSI 7" Screen (B-LCDAD-RPI1) but there is no firmware support from either company. Does anyone have any information on how to get the two compatible? and if not, is there any other suggestions to upgrading the 4" DSI screen to a different 7" screen that would be much easier to use? Our search so far has been unsuccessful.

Any help at all would be appreciated, Thank You!

[Tesla DeLorean]

Whatever the screen, it is about the clocks, and the sync, porches and active line lengths. Might have to adapt the existing DSI examples to program alternate parameters.

Can probably pull the values from the Linux source.

Touch via I2C?

Seem to recall a YouTube video of the RPi screen on a STM32F769I-DISC1 with adapter. I've got the HDMI working across a variety of screen resolutions.

I have an RPi screen and adapter, would just need to be worth my while.

[CLued.1916]

I've looked and there is no such help on youtube unless you have a link?

[CLued.1916]

clive1,

I do think it is doable to get the two compatible, but seems to be very challenging. Is the HDMI method an easier route to go? or would it require the same amount of driver work and issues?

Thank You!

[Tesla DeLorean]

I'm probably the wrong guy to ask, the primary complexity here is getting workable settings. With the HDMI there are arguably more moving parts, more display modes, and more narrow/fussy displays (wants VESA normative parameters).

The RPi display should be somewhat simpler, as you have one panel, it has a relatively broad set of acceptable parameters, and you just have the LTDC+DSI to contend with.

The display at minimal clocking is around 31 MHz for 60 Hz refresh

The 800x480 would paint as 976 x 528 for line totals. I think I can make the math work.

[CLued.1916]

clive1,

There is Drivers that are meant for Linux for the RP Display. I'm not familiar with that language but it seems like it gives most of the necessary information. It just needs to be converted to a usable C++ driver profile. From your more known expertise in lcd drivers, does that appear to be the case?

Link: https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c

Thank You!

[Tesla DeLorean]

Spent some hours on it last night, was able to talk to the ATMEL chip via I2C, and the Toshiba DSI part via that.

Was able to power up, get the backlight functioning, getting random stripes on screen so not clear it is getting DSI rasters, or if able to send commands via DSI.

LTDC, DSI and clocks/plls looked to be ok, so probably outputting data.

RPi code doesn't look to set screen geometry into ATMEL or TOSHIBA parts.

Don't have suitable test equipment to evaluate.

[CLued.1916]

clive1,

Were you basing your code off of that RPI code? I don't see anything either that attains to the geometry of the ATMEL or TOSHIBA, just register values and I2C write and read functions for those chips.

What equipment are you using at the moment to do this?

Thanks!

[Tesla DeLorean]

I have a 100 MHz scope, but lack a schematic or details of the RPi LCD board or effective way to probe.

Using an STM32F769I-DISC(O/1) boards, with DSI panel, HDMI adapter, and RPi adapter.

An Element 14 RPi 7" panel kit.

I'm talking to the panel using that code, or derivatives of it. And STM32 side code configuring the SDRAM, PLL, LTDC and DSI

[TDJ]

@Community member​ , I wonder if you succeeded and, if so, could share your experience.

I am struggling with exactly the same challenge.