Contrast Problems with C12864WO-B1TFH#-M COG Display
We are looking to replace an obsolete Kyocera display with this display. We have been using COG displays for many years so we are familiar with the electronic volume / resistor ratio schemes on these devices. Our circuit design has all the capacitors required for the 4X booster but without the external pot for contrast adjustment. We have always used the ability in the software to adjust the contrast with great success for thousands of displays.
Using the code contained in the specifications yielded a blank display, so I have tried various combinations along with calculating from the charts and formulas with no success. The latest version of code I have tried:
comm_out(0xA2); //added 1/9 bias
comm_out(0xA0); //ADC segment driver direction (A0=Normal)
comm_out(0xC8); //added
comm_out(0xC0); //COM output scan direction (C0=Normal)
comm_out(0x40); //Operating Mode
comm_out(0x25); //resistor ratio
comm_out(0x81); //electronic volume mode set
comm_out(0x2F); //electronic volume registerset
comm_out(0x2F); //power control set
comm_out(0xAF); //displayON/OFF - set to ON
I know that something needs to be adjusted but I am at a loss as to what ... Here are the voltages I measured on V0 -> V4:
V0 = 5.1V (pin 26)
V1 = 4.6V (pin 25)
V2 = 4.1V (pin 24)
V3 = 1.2V (pin 23)
V4 = 0.6V (pin 22)
VOUT = 12.9V
I also noticed that V0-V4 are slowly increasing if that means something
Larry
-
Hi LarryA,
The NHD-C12864WO-B1TFH#-M display would require an external contrast control using a potentiometer in order to properly tune the contrast to have the pixels appear as needed. Using just the electronic volume command will likely not be enough to tune this display.
Please try using the setup listed in our datasheet and see if this will resolve the issues of a blank display.
Best,0
Please sign in to leave a comment.
Comments
1 comment