i've been fighting a similar fight a couple of days ago ... the routines in the last posts work but the basic idea is there ...

http://www.lcdforums.com/forums/viewtopic.php?t=1893

please let me know if you have problems with my technique .. and also any suggestions for improvements.

I was asking many of the same questions you're thinking right now ... i posted some of my code at this link in the hardware forum

http://www.lcdforums.com/forums/viewtopic.php?t=1893

you could check out the hail_LCD_display function. the basic stuff is there. i could send you the final code if you ...

I forgot to mention ... I am running the PIC 18F452 with a 4MHz clock and soon to be 40MHz. I do not use any delays within the code to try to slow the transmission of data.

One suggestion - An even more efficient implementation can use ISRs to supervise the transmission of the data bytes if an ...

OK! after 6 days of ponderation and deliberation about the true meaning of that criptic passage ala section 2.2.3 of our spec sheets.
Im posting some of my code that seems to be working for the sake of contributing to the wealth of knowledge at this forum. The code seems to be working fine. I can ...

The two GLC24064 displays that i purchased both send NACKs (most likely) when data was sent too quickly.
just to be clear, the NACK or ACK is sent by the display (the slave) and not the PIC (master) - that is another reason section 2.2.3 is not clear.

The display does not implement flow control on ...

I've been reading a couple of posts that have dealt with the I2C communication. You (the techs from matrix orbital) insist on directing everyone to section 2.2.3 in the manual. My English is not the clearest, however, I don't think this section is the clearest of descriptions of the shortcoming of ...

These are two of the functions that i use to manipulate the backlight. it got complicated when i decided to check for acks after each byte was transmitted.

void LCD_backlight_on(int state, int on_duration){
int ack = false;

setup_flow_ctrl(); //start hardware timer - 40ms to complete ...

I seem to have the nack (no pun intended) of receiving nacks on the I2C bus! I can't seem to send any commands without receiving a nack on at least one byte. however, i can't seem to communicate with the device unless i cycle the power supply.

Can anyone tell me how to regain communication with the ...