• We recently switched our forum platform. If you experience any issues please email support@crystalfontz.com

Command OK, no Data!!


New member
Hello all,

I have a S6B1713 controller on a Bolymin 80x32 GLCD. I am controlling the LCD with a PIC 18F452 running CCS C. I have successfully set up the LCD screen, I can control the contrast, all pixels on / off etc, with the control messages. But when I come to send data to the screen, it will not display anything. I have probed the Data / CLK / RS lines but nothing appears on the screen.

Any help would be much appreciated, TIA.

Data sheet for LCD:-
Data sheet for controller:-
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.
If you are able to initialize and control contrast, pixels on/off, etc, then the data bus is functional. This makes it seem like the RS signal is stuck in the command state. Recheck your wiring; measure the signal levels at the display input pins.

Or, it could be something simple like you are not issuing a "display on" (0xAF) command during or after your init. That command is independant of the "entire display on/off" (0xA4/0xA5) command, which will override any graphic data you have sent.


New member
I have checked the RS line, it does go high before data is sent to the LCD. Only thinkg is that I have a 10ms delay between the clocking pulses, i.e. Clock goes low, data goes on pin, wait 10ms, clock goes high, wait 10ms, clock goes low again. I ma not sure if this is too slow (minimum time for this LCD is something like 180ns!!) But if this was too slow then the command lines should not be working??
I am issuing a screen on command (0xAF) at the end of the initialisation.

The 10 mS delays should not prevent the code from working. Maybe you should post your code (as a file attachment) so we can see if there might be another problem.