I've made some code optimizations to try to reduce the display printing times.
Got it to a minimum still using only the STM32 but even at idle engine I got some connection fails and retries.
So the "diy" "hacked" UART TX signal inverting using an interrupt might be ruining the communication. Either that or the long cable carrying the UART signals from the OBD plug location to the dash... :) I have to fix the inverting and retry...
Meanwhile I got the ILI9341 to refresh at 60fps on the ESP8266 xD
I'm able to run the display at 80Mhz SPI speeds!!!! xDDD