LC79400+LC79430 drivers

This is some code to drive the LCD displays found in bulk in a box at ETA.

The pinout is as follows:

1. FLM - Frame load
2. LOAD - Load row
3. CP - Clock pulse, load 4 pixels
4. NC - Not connected (other modles have M-line, to toggle for contrast)
5. Contrast, potentiometer wiper from VEE to GND, to give range around -17V to -30V
6. VDD - 5V
7. GND
8. VEE - LCD drive voltage. VDD - VEE <= 32V, so VEE should be around -25V
9. DI 1 - Data line 1
10. DI 2 - Data line 2
11. DI 3 - Data line 3
12. DI 4 - Data line 4
13. \DISP OFF - inverted display off. Connect to VDD
14. NC - Not connected

The rp2040 and nrf folders have code for the Raspberry Pi Pico and some nrf chips respectively. The rp2040 code uses a PIO state machine anlong with 2 DMA channels in order to draw to the screen completely in the background without any interraction by the core.

The backlight is a CCFL tube, so unless you are in the mood to play with hundreds of volts you should probably swap it for some LEDs.

The lcd.c files in both folders have more info on how the display and the drivers actually work.