3-wire LCD interface?

[Dwayne]

Hello Folks,

I will post the receiver and transmitter part of the 1 pin Xcvr.

The principal lies upon the receivers timing, in connection with the transmitters timing. You only have two critical points to ponder.

1. The initial Rcvr *must* be slower than the transmitter until it receives the start bit.

2. The Rcver *must* be faster than the transmitter after receiving the start bit.

After #2 starts or begins, you control your Baud rate by the transmitter, *NOT* the receiver, or both.

I wanted the overhead of the transmitter to be almost zero. The receiver was a 16f648A, and its only job was to control the LCD, so instead of using a interupt (which you can), I left the receiver in a loop, waiting for data communication from the 12f675. When a full byte is received, the 648 checks to see if it is a LCD command byte or a LCD data byte. (x254) if it is a command byte, it tells the LCD to accept next byte as a command, and waits for the next byte.

Dwayne


It has been 100 percent reliable so far. When I get home, I will post the code.

[shahidali55]

Melanie could you please give me the code to interface your circuit?

[phoenix_1]

Pa de si bre Vlad puno pozdrava od Tanga.

[skimask]

Melanie could you please give me the code to interface your circuit?

That was over 3 years ago...you know that right?
And there is code around here...just needs a bit of searching...who knows, maybe you could even write code yourself!

[T.Jackson]

That's a good idea - using a Hex D Flip-Flop. So basically when Q6 is low the LCD's disabled, (the diode sinks current from the 4k7) then Q6 swings high allowing the data line to re-enable the LCD after clocking in the bits you want.

[T.Jackson]

That was over 3 years ago...you know that right?
And there is code around here...just needs a bit of searching...who knows, maybe you could even write code yourself!

Give him a break - writing code for this is a lot easier said than done.

[shahidali55]

Couldn't find anything using search.

[shahidali55]

I didn't know what PBP was before 3 years.
I don't think any code in PBP was posted for 3 or 2 wire interface till now.
I tried to understand the code given on http://www.rentron.com/Myke1.htm.
But couldn't really understand the command sequence. I didn't really get how the RS and E lines of the LCD are being handled.

[skimask]

I didn't know what PBP was before 3 years.
I don't think any code in PBP was posted for 3 or 2 wire interface till now.
I tried to understand the code given on http://www.rentron.com/Myke1.htm.
But couldn't really understand the command sequence. I didn't really get how the RS and E lines of the LCD are being handled.

That's the same book/code/idea I was talking about. I picked up that book back in '01 (give or take a few months). Basically you manually preload a shift register with all the data bits, then the rest of the control bits and the last thing to get 'tripped' is the Enable, all done by a shift register.
Not a new idea by any stretch, but a handy one...

[Archangel]

I didn't know what PBP was before 3 years.
I don't think any code in PBP was posted for 3 or 2 wire interface till now.
I tried to understand the code given on http://www.rentron.com/Myke1.htm.
But couldn't really understand the command sequence. I didn't really get how the RS and E lines of the LCD are being handled.

Look at this thread:
http://www.picbasic.co.uk/forum/showthread.php?t=4972
HTH
JS