Newhaven Display Forum

Newhaven Products => Character LCDs => Topic started by: fidodido18 on September 08, 2014, 11:27:32 AM

Title: PIC32 and NHD-C0220BIZ-FSW-FBW-3V3M problem
Post by: fidodido18 on September 08, 2014, 11:27:32 AM
Hello Newhaven Developers,

Sometimes the COG does not show anything on the screen, and my microcontroller show me a NACK reception of the LCD.
Please how to prevent this problem?

My system:
1. Microcontroller: PIC32MX795F512L
2. LCD: NHD-C0220BIZ-FSW-FBW-3V3M

I have 500 LCD in stock for this project. :'(
Title: Re: PIC32 and NHD-C0220BIZ-FSW-FBW-3V3M problem
Post by: Michael_L on September 09, 2014, 08:41:11 AM
What speed are you running your I2C bus at?  Also, what value pull-up resistors are you using?
Title: Re: PIC32 and NHD-C0220BIZ-FSW-FBW-3V3M problem
Post by: fidodido18 on September 12, 2014, 08:41:05 AM
What speed are you running your I2C bus at?  Also, what value pull-up resistors are you using?

Hello Michael L,

thank you for you help.

I have connected my LCD with extension cable (9 in).

I have 4.7 Kohm pull up resistors. And the i2c bus frecuncy is 200 khz.
Title: Re: PIC32 and NHD-C0220BIZ-FSW-FBW-3V3M problem
Post by: Michael_L on September 12, 2014, 09:12:06 AM
Thank you for the  information.  Can you please try using 10kΩ pull-ups just to test for the ACKs?  Also, is it possible to try slowing down your I2C speed to 100kHz?  I just want to see if this results in any differences for you.
Title: Re: PIC32 and NHD-C0220BIZ-FSW-FBW-3V3M problem
Post by: fidodido18 on September 19, 2014, 10:01:32 AM
Thank you for the  information.  Can you please try using 10kΩ pull-ups just to test for the ACKs?  Also, is it possible to try slowing down your I2C speed to 100kHz?  I just want to see if this results in any differences for you.

Hello Michael,

thank you for your help.

I have hardware problems with the RESET PIN. I changes the Microcontroller pin direction and change the pull up resistor and I2C speed and now all is OK.


thank you very much.