Hello,
I would like to control contrast of Hitachi LCD Display HD44780 from microcontroler.
Is using digital potentiometer like X9C103P good idea?
Think about it. You have 3 cases:
- Clear display.
- Blurred display
- Invisible display.
I can understand the point of (1). Occasionally you might want (3).
Why would anyone want (2)?
If you have a stable 5V supply, 16x2 modules need adjusting once in their lifetime.
In practice, connecting VO to GND will give you reasonable contrast.
If you have an unreliable low voltage battery, you might need to generate a negative VO voltage.
Yes, you can do this with PWM to a charge-pump circuit.
You can probably monitor VCC and automatically adjust the PWM in a battery app.
OTOH, you probably would not choose a 16x2 in a low power battery app.
David.