[SOLVED] 8051 to LCD PCB interfacing

[natasie]

hey everybody

i have a problem with my circuit. i connected my LCD 16x 2 to my microcontroller and i am not getting any display on it. when i tested it on the breadboard it worked perfectly. but now that i di my pcb and i am not getting any display on it. i can see that the LCD is receiving the message but it is not just displaying it. i have checked and there is connectivity between all the pins of the mcu. i do not know what could be causing this problem.

please any help with this??

 

[ckshivaram]

check individual track connection from controller to LCD pins.
Ensure you have connected 10K pull up resistor to all the port pins.
check if you have connected 10K pot to pin 3 of LCD.
check by turning the 10K pot if you can see black boxes in LCD.

---------- Post added at 19:05 ---------- Previous post was at 19:03 ----------

check the voltage on LCD supply pins and check if the port pins are showing correct logic for the data you are sending. check it on the controller pins also.

 

[natasie]

i have checked the individual port connections. they are all connected properly. and the LCD is showing black boxes but the actual characters are not being displayed. do you any advice for me??

 

[ckshivaram]

please update the pull up resistor at all port pins. and do a reset after powering on. and adjust the contrast till you see the characters.

 

[natasie]

wont i only need a pull up resistor for port 0. i am using port 2 for the data pins and pin 1.5 to 1.7 for the control lines. and when i tested it on the breadboard, it worked without the pull up resistor. i do not know why its not working now.

 

[ckshivaram]

connect pull up to all the port pins. ( mandatory)
put lcd to breadboard and see if it is still working, then use the same controller on your board. try adjusting the delay as the last option.

 

[natasie]

ok i will try it and get back to you. but i am worried that it might cause a voltage drop in the circuit.

 

[ckshivaram]

practically nothing will happen. also post the circuit you are using........

 

[natasie]

thank you Chivsram, its working now.