74HC164 to drive a LCD panel

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Does anyone have suggestions/experience with using an 8-bit serial-in,
parallel-out shift register like the 74HC164 to drive a LCD panel? I have
been using a LCD module in 4bit mode, and want to try something a little

How about hints for using 2 of these in tandem for a 2 digit LCD? 3 in
tandem for 3 digit?...

It would be useful to know how to use a SPI port on a tiny AVR w/ the
shift register for driving a simple LCD display.

thanks to any an all replies

Re: 74HC164 to drive a LCD panel
sonos scrobe on the papyrus:

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Use 74HC595 rather than '164. It is closer to SPI.


John B

Re: 74HC164 to drive a LCD panel

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You have to drive lcds with ac waveform, quite tricky. there are
numerous driver chips around.

Re: 74HC164 to drive a LCD panel
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The AY0438 (Microchip makes it these days) works pretty well for
driving LCDs. But rolling your own is fun and if done right can be very
low power.

I've done the drive a shift register thing. Used CD4094, same idea as
74hc595 but cmos and works better at 3 volts. 4 of 'em will drive a 4
digit 7 segment lcd display and leave a few bits left over for colon or
decimal points. The only tricky part is you need to generate an AC
driving waveform in software. I just updated the shift register 60
times a second and made sure I inverted the output data every other
time. At a reasonable clock speed, 60 hz is pretty simple to do with a
simple timer interrupt.


Re: 74HC164 to drive a LCD panel

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John Fields
Professional Circuit Designer

Re: 74HC164 to drive a LCD panel
On Thu, 17 Nov 2005 16:20:47 -0600, the renowned sonos

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Yes, you can easily drive a static LCD with daisy-chained HC595s. Be
sure to write your firmware so that you keep the average DC voltage
across the segements in line with the specifications (typically
something like < 50mV).

Multiplexed LCDs are trickier- I think you'd need a pack of resistors
and I/O that can be individually tristated.  

Or just use a micro with an on-board controller (but that severely
limits your choice of micro).

Of course there are a number of driver chips available, but they tend
to be a bit expensive.

Best regards,
Spehro Pefhany
"it's the network..."                          "The Journey is the reward"
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Re: 74HC164 to drive a LCD panel


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