Code for implementing 16*2 LCD with HC11 uC in 4-bit mode

[ZeleC]

16*2 LCD

hello guys.
Can anyone direct me to a link or upload some source code in assembly regarding the interface of an 16*2 lcd with a hc11 uC( or any other uC) in 4-bit long mode.
thx

 

[Iain]

Re: 16*2 LCD

This sample provided with Proteus might give you a few pointers ( written in C though).

 

[ZeleC]

I managed to make the LCD work in 4-bit mode the problem was with the busy flag .IN 8-bit mode i used to check for DB7 , that didnt worked in 4-bit, so i replaced this routine with a delay of 40us, and now everything works.
But did anyone had this problem before(not able to read the BF)?

 

[C-Man]

Re: 16*2 LCD

I use all my LCD's in 4 Bit mode to save pins and never had a problem to check the busy flag which is the MSB of the first Nibble that you read in.

hope this helps

 

[Iain]

Re: 16*2 LCD

To read the Busy flag in 4-bit mode you must perform two read operations.

First read operation reads in the high nibble, second read operation reads in the low nibble. Amalgamate the two nibbles to form a byte indicating the busy status and ddaddress and then test the busy flag.

A single read operation (as in 8-bit mode) will throw you out of sync.

 

[dainis]

Re: 16*2 LCD

I have a nice PDF, for LCDs. Unfortunately, I don't remember the link, so I'll upload it.

Search by Google ....
h**p://www.optrex.com/pdfs/Dmcman_full.pdf

 

[ZeleC]

I think Iain has a point
ill try it,i was only taking a one time reading
thank you guys

 

[ZeleC]

Thank you guys for the help
its worked and here is the code for the lcd busy flag
(im using expanded mode )
there is no need to form a byte out of the two nibbles
WI PSHA
WI1 LDAA LCDCTRL ;DISPLAY NOT BUSY\
LDAB LCDCTRL
TSTA
BMI WI1
PULA
RTS

 

[amsbhole07]

what is the difference between 8-bit and 4-bit LCD