LCD issue

JoaoSantos · Posted: Tue May 06, 2008 2:16 pm

Hello,
I have an application where I use an 16x2 LCD display. When there is a power spike (the LCD only works if VDD = 4.7 V), the LDC displays garbage, but the PIC's main program continues to work.

I try to use an EMC filter in the power supply but it did not solve completely the problem.
I also tried to use the BROWNOUT fuse with 4.5, it "solves" the problem since the PIC is restarted along with the LCD, but my intention is to the program continue running even if there is a "small" power spike.

Using lcd_init() continuously is not an option since it takes a long time and the LCD text appears with flicker.
Any ideas?
Thanks in advance.
Best regards.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

http://www.ccsinfo.com/forum/viewtopic.php?t=26718

JoaoSantos · Posted: Tue May 06, 2008 3:15 pm

Hello thanks PCM,
The problems described in the answer goes in accordance to my problem: a voltage dropout caused by EMI, or other kind of noise affect severely the LCD but not the PIC (it is logic because the noise margin of the LCD is much smaller compared with the PIC).
But unfortunately they don't say how it is possible to solve the problem. I'm already using an EMI filter.

I thought in using the LCD_readByte function to see if the character displayed is different form the one I sent. if so, i would reinitiate the PIC.
What do you think about this idea?
Once more thank you
João