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Driving LCD 7-seg passive displays with PIC

I have a passive LCD with 8 7-seg digits plus point and some other symbol. It has 23 connections. I wish to drive it with a PIC that has LCD module built-in but I have seen that all PICs capable to drive LCD have only 4 commons. I supposed that was needed 1 common for each digit but probably I have to use bias plus multiplex. In this case how can I do? I have not found any application notes and info on internet. Thanks.

Reply to
cyberbige
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You can use a port expander. Microchip has at least one of these, and there are app notes on how to use them. You can also use serial in - parallel out shift registers to drive these things. That is probably easier to control. Using these, you can drive all the bits with 3 GPIO pins. You will need 3 of them.

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Regards, Bob Monsen

Reply to
Robert Monsen

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