LCD - Blocks at Start-up/Initialisation

[Rob]

Hi,

I am using a PIC16F877A to output to an LCD in 4 bit mode. For the 1/2 second start-up time needed before instructions can be sent to the LCD, I have blocks on the screen. I have noticed this when using other PICs as well and I realise that it is the test routine for the LCD and not the PIC. I am wondering if there is any way to eliminate this from being visible at start-up?

Thanks

[mister_e]

disable the Vo line of your LCD. Vo is the contrast pin. Usually when you tie this pin to VCC you'll see Nothing

[Rob]

I was wondering about using the contrast line to achieve this.

Thanks very much

Rob

[Dave]

Rob, Just tie the one side of a 10k pot to a spare micro pin of choice and the center of the pot to the VO line and the bottom of the pot to ground. Now with the pin outputing a high state adjust the pot for the correct contrast. Now during startup your code will output a low on the pin untill you want the display to be enabled and then just set it to a high state for display.

HTH,
Dave Purola,N8NTA

[Rob]

Originally posted by Dave
Rob, Just tie the one side of a 10k pot to a spare micro pin of choice and the center of the pot to the VO line and the bottom of the pot to ground. Now with the pin outputing a high state adjust the pot for the correct contrast. Now during startup your code will output a low on the pin untill you want the display to be enabled and then just set it to a high state for display.

HTH,
Dave Purola,N8NTA


Thanks for that - it works perfectly!

Rob