Newhaven Display Forum

Newhaven Products => Character LCDs => Topic started by: mhathaway on February 25, 2015, 06:14:11 PM

Title: NHD‐C0220AA‐FSW‐FTW Contrast
Post by: mhathaway on February 25, 2015, 06:14:11 PM
I am using the NHD‐C0220AA‐FSW‐FTW and it works great on my first board.  I am trying to get a second board up (same PCB design, same software), but the nothing come on the LCD.  I think that it's a contrast problem but no matter what voltage I put on pin #2 (3.3V down to .013V) I can't see my text.  Here are the voltages on my pins:
1. 0V (gnd)
2. adjustable, but trying 0.1V and lower
3. 3.3V
4. Mostly 3.3V (brought low during instructions, but defaults at high)
5. 0V (gnd)
6.  Mostly low, brought high during messages
7-14. Parallel message.

Any ideas on what i should try?
Title: Re: NHD‐C0220AA‐FSW‐FTW Contrast
Post by: Retheesh_M on March 03, 2015, 11:53:43 AM
For pin 6, you should start at high and then bring it low during messages.  The timing diagram on page 8 of the specification sheet shows how the Enable pin (E) should go high first and then low.  Also if you are checking the busy flag during initialization, it is recommended to use a delay instead because this controller is known to have issues with the busy signal as noted on page 5 of the specification sheet.