And that there is something in the programming sequence for the panel after power-on.
Most likely. I am starting to read register values as described in the Panel data sheet plus some more with description scattered around several places...
Currently I am adding some code to read all available registers - and if I do a mistake (register does not exist or has >1 byte contents I already get reasonable error messages).
It starts to look like that we have to send one or two more "standard" commands that are not included in the panel data sheet.
So still no backlight - but close.
If we had the official R63311 data sheet... But Renesas is Japanese and a little closed.
The one for the R61523 is similar so that I can learn a lot - but it is definitively not exactly the same command set.
BR, Nikolaus