I got hardware SPI working with the Nokia 5110 LCD.
I used a GPIO for the chip enable, and an interrupt for bringing CE high after transmission.
I've attached the code below and a small graphics library that I put together from various sources on the web.
One thing I found confusing was there seems to be no interrupt flag set when the SPITXBUF empties.
So in the situation like this one where the Rx of the SPI is not even being used, to get the interrupt to work
you still use the Rx ISR.
Here is my interpretation: Write data to SPITXBUF data shifts through SPIDAT and is transmitted out SPISIMO,
simultaneously the same data is shifted into SPIRXBUF and SPI INT FLAG is set. Then you use the Rx ISR to read
the SPIRXBUF and that clears the SPI INT FLAG.
Is this correct?
Also the documentation on the FIFO is somewhat vague for the inexperienced.
How would I go about using the FIFO for this example?
Here is a short video: