use a led matrix 5x7 without driver chip?

Thanks for the picture... you got it in while I was compiling the post #4.

I do not know how the dots are arranged in the buffer bytes... but it can be found out... You also may face the 'reverse' issue... but that's easy: you just put out a filled rectangle in 'white' and write in 'black'.

Btw, I noticed two resistors going to same B7 PICO GPIO pin instead of B7 and A8. But I guess this will not solve all you problems...