Connect LCD to Atmega using 3 wires
After I implemented interfacing LCD to ATmega8 using 2 wires http://www.scienceprog.com/interfacing-lcd-to-atmega-using-two-wires/
I decided to make another one example but with 3 wires. Using 3 wires makes control much simpler as it is easier to control data flow to shift register. Here I used the same super cheap 74HC164 serial in parallel out register.
LCD to shift register is connected in 8 bit mode. LCD strobe pin E is controlled with Atmega’s PC2 pin. Register is clocked with PC1 and data is transferred with PC0 pin. Notice, that I used same data line (PC0) to control LCD RS pin. RS pin is controlled in this way: after 8 bits are sent to shift register, then enable data line by setting “1” (PC0) without clocking and after this LCD E pin is strobed. For more details take a look at my source code at the end of article.
If there is any questions, don hesitate to ask.
Source code:3 Wire LCD interface to ATMEGA
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September 30th, 2006 at 6:37 pm
there are any problem in using 74LS164 instead 74LS164?
tks,
Christiano
October 2nd, 2006 at 1:28 pm
There shouldn’t be any problems with that.
March 27th, 2007 at 1:26 pm
What is the value of R2?
March 27th, 2007 at 2:19 pm
In my actual circuit I have used 10k. This may vary I think from 4.7k as it is Pull-Up resistor only.
March 30th, 2007 at 10:01 pm
Which is the value of r2?
April 20th, 2007 at 4:06 pm
Why the lcd only writes a series of squares instead of the word test?
July 13th, 2007 at 2:08 pm
Why you didn’t use SPI on ATMega ?
connect SCK,MOSI to 74*164 inputs, D4..D7 and RS to outputs.
and i.e. SS pin to EN - 3 lines - lcd in 4bit mode :)
it’s much easier to program it (IMHO)
Best Regards
Vaitek
July 13th, 2007 at 11:36 pm
Using SPI s a good idea. Maybe I will try to simulate this version. Only one disadvantage of such connection is that hardware is tied to SPI pins instead to any MCU pins. I bet programming should be more easy using SPI.
February 8th, 2008 at 2:33 pm
can just use any LCD or must be the one you are using?
February 8th, 2008 at 4:27 pm
Any standard alphanumeric LCD based on HD44780 controller.
February 17th, 2008 at 4:05 am
I’m need PB3, PB5, PD5 to connect LCD. Help me.
February 19th, 2008 at 4:52 am
Why my lcd write UESU! instead of TEST!.I use od-dm1601b,tks.
February 19th, 2008 at 11:29 am
Do you use standard LCD? Are all connections made properly? Because this circuit should work properly - tested myself.
March 31st, 2008 at 9:26 am
hey kindly help me
i have atmega 8 and displaytech 16*2 lcd ……i want to display some text when the ir sensor connected to its adc port is interuppted.how to go for it
May 7th, 2008 at 2:51 am
Hi,
Does the shift register have to be controlled by the adc pins on the atmega or can another port be used?
Thanks
May 7th, 2008 at 10:52 am
You can use any I/O pins for this. Of course you need to do changes in software definitions.