Wemos D1 mini pro about ssd_13xx HOT 2 OPEN

I think I'm seeing the same problem on a generic ESP-12E module I've got wired up on the breadboard to a SD1331 display from eBay. Any text at setTextScale(1) is missing every second line, though setTextScale(2) and up works OK. I tried several fonts and they all did the same thing. fillRect() works, but drawPixel() does not. lines do work, circles don't.

It feels like something is wrong in the single-pixel draw routines. Anything that uses fast H or V lines (rects, lines, big fonts) to draw many pixels at once seem to be OK.

It took me a while to figure out how to wire it up. Seems like the HSPI-CS pin (GPIO15) is being used as CS no matter what I say in the code.

Otherwise it's very fast, the colors are nice, and I wish it was working. I may have to dig into the code myself and see what's up. I suspect it's some bitwise math the ESP8266 compiler is doing it's own unique way, or perhaps some issue with very short SPI transfers.

from ssd_13xx.

Of course, ten minutes after posting it started working. (then stopped, then started again) I now think it's to do with the DC pin choice (The behavior was the same when I deliberately set the DC pin wrong.) I haven't fully deciphered the logic, but pins GPIO5 and GPIO4 seem to work as DC sometimes, but GPIO16 does not.

from ssd_13xx.