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. I wish to use a 16F917 PIC.
Driving LCD 7-seg passive displays with PIC
Sep 18, 2008
9 Replies
Not really necessary.
You have to double check it for sure, but 8 digits would need 64 segments. 23 pins (19x4) can drive 76 segments. So, it should be possible.
What does the data sheet for the LCD show? Definitely multiplexed, probably by 3 or maybe 4. You need that information.
That's fine.
Nope.
Best regards, Spehro Pefhany
"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
"The Journey is the reward"
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eff.com
Can you explain me how the multiplexing with biasing works? I cannot understand how to connect the wires and why there are different levels of voltage in common pins rather than only 3 (-V, 0, +V).
Yes, but it's faster to google it:
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Best regards, Spehro Pefhany
"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
There are four common lines from the uC to four common lines to the LCD. It is definitely a one-to-one mapping.
No, I was asking this for later programming the uC.
You just set bits in the registers. Please read the manual.
Why do you bother to answer gmail questions ??
donald
What do you mean?
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