Incorrect mirrored image on LTCD but correctly on TouchGFX

[RMoli.3]

I am working with a STM32F767 with an LTCD panel but the image it is displayed on the panel weirdly mirrored.

Current configuration and checks that I have done:

• I have located the frame buffer in external RAM.
• I have checked that the initial values of the frame buffer on rame contain RED colors ( which should be displayed on the top left corner)
• Checked that the panel orientation is correct (according to datasheet)
• Working with RGB565

From what I understand it looks like TouchGFX is fillinf the frame buffer correctly but it is being incorrectly displayed. Any ideas of what could be causing this flipping?

I have already worked with this panel with an evalboard and the STM32F769 and everything as working as expected.

[heyo]

Is it custom board? Does your LCD screen have SHLR and UPDN pins?

[RMoli.3]

Yes it is custom board. From your comment I understand that SHLR and UPDO refer to the pins of Left/Right and Up/Down scanning. I did check that the LTCD does indeed have U/D L/R which seem to be unconnected and probably are the cause of the flipping. Prototype on the eval board had them connected to Vdd/Gnd as was probably the cause of it working previously. Will update after more testing.

[heyo]

You can try to connect SHLR and UPDN to microprocessor and change them programmatically.

[RMoli.3]

The thing is that we do not have many IO left that is why it was HW configured. Luckily the HW was prepared with pads to force both direction by soldering/desoldering bridges.

Summary: the issue was HW related to the incorrect SHLR and UPDN pins configuration

[heyo]

You can one pin hook up to ground and another to 3.3V and see what changes