• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Bias Voltage for Multiplex LCD Question

Not open for further replies.
I have a multiplex LCD (datasheet attached) that I want to use with the PIC16F913 from Microchip.

I understand that multiplexing uses multiple commons, but how do I know how many bias voltage levels to use? I attached a section of the datasheet dealing with the LCD driver. They have a typeA and typeB waveform, but that just deals with the phase. They also have a 1/3 mux, 1/2 bias and a 1/3 mux, 1/3 bias to choose from.

The LCD datasheet has nothing about bias voltages - how do I choose which combination to use? Can I use either? Thanks!



Well-Known Member
I've used the 16F917 with a static LCD and it was fairly easy. Try breadboarding it first with the 3 10k resistors as shown in the datasheet. Search the forums here for Cricket and you can see my code & schematic.
I breadboarded it and coded it for 1/3mux with 1/3, then 1/2 bias (both type A waveform). When I set it up for 1/2 bias, the segments that aren't active show up faintly, but I can see them. That doesn't happen when I set it up with 1/3 bias.

Any idea why one would work better than the other?
On the VLCD pins in 1/2bias:

VLCD2: 2.5V
VLCD1: 2.5V

In 1/3bias:
VLCD2: 3.32V
VLCD1: 1.67V

I tried it with both type A and B waveforms, both have the same results of poor quality in 1/2 bias mode.
Not open for further replies.

Latest threads

EE World Online Articles