Notes on using the Nokia 5110 display


Firstly, the display uses 3.3 Volts.


SPI Bus
The Nokia display is mode 0 SPI.
I used a SCK rate of 8MHz/128

Note that SS MUST be an output or there is a danger of the SPI bus going into slave mode.

There is some example code based on the Sparkfun example. See the P31 website for download.

I had to make the following changes to the software:

change references to char to be uint8_t
change references to byte to be uint8_t (but beware LCD_clear needs a uint16_t)

I defined my own RST,D/C,and SCE pins.
I then defined all my outputs at once in the normal port_direction_init() function
It is necessary to initialise the SPI bus using:
	init_spi(3);			// (I used 3 to go as slow as possible)

If you change the pins, use make clean to force a recompile.


I modified LCDWrite to look like:

//There are two memory banks in the LCD, data/RAM and commands. This 
//function sets the DC pin high or low depending, and then sends
//the data byte
void LCDWrite(uint8_t data_or_command, uint8_t data) {

	if (data_or_command) {
		PORTB |= (1<<PB2) ;					// D/C (data / command)
	} else {
		PORTB &= ~(1<<PB2) ;
	}
	PORTB &= ~(1<<PB3) ;					// CE (Chip enable, active low)
	xmit_spi(data);							// From spi2.c
	PORTB |= (1<<PB3) ;
}


Note that programming also uses the SPI bus, so you must disconnect the LCD during programming.
There are dual-in-line switches available to make this easier.