SerLCD 2.5 with strange display issue

Development Boards MicroMod
1

Hey everyone,

I’m using the LPC2106 board from SparkFun, along with the SerLCD v2.5.

I finally got it to work, and I have some very basic code to read characters from the keyboard on UART0, and either spit them out to UART1 or send lines of text, etc.

Anyway, what I’ve noticed is that the display won’t load as you’d expect, from left to right, all 20 characters, before wrapping to the next line (this is a 4x20 display). It goes like this:

  1. Starting on Line 1, the first 16 characters fill as normal, but then it wraps to line 2

  2. It fills the first 16 characters of line 2, but then jumps back to character 17 on line 1, completing the row (characters 17-20).

  3. It then wraps to line 3, filling the first 12 characters (not 16, like before).

  4. It will then wrap back up to line 2, and complete the row (characters 17-20).

  5. It then moves to line 4 and fills the first 12 characters before wrapping back to Line 1 to repeat the process.

If it helps, it looks like this. This test was performed by echoing exactly what was typed on the keyboard. I used the English alphabet, first in caps, then in lower case, then in caps again.

ABCDEFGHIJKLMNOPghij

QRSTUVWXYZabcdefwxyz

klmnopqrstuv

ABCDEFGHIJKL

So, the summary here is that the screen isn’t populating properly. I tried the clear screen command (0xFE followed by 0x01), which functionally cleared the screen but didn’t affect the character fill order.

Also, I seem unable to populate the last 8 characters of lines 3 and 4.

Has anyone seen anything like this before?

2

Your SerLCD thinks that it has a 4x16 LCD connected, rather than 4x20. I believe there’s a special character sequence you can send to it to change that.

3

Yup, page 2 of the datasheet…

4

Thanks, guys. I’ll give that a shot this weekend.

…FartingMonkey92, eh? Great name! :slight_smile:

5

That got it.

I saw that section of the manual, but since the serial backpack came pre-attached to the LCD, I figured it should have already been set up to expect the 4x20 screen. Apparently they missed one.

No matter - it was an easy fix. Thanks for the quick responses!

6

eewestcoaster:
I saw that section of the manual, but since the serial backpack came pre-attached to the LCD, I figured it should have already been set up to expect the 4x20 screen. Apparently they missed one.

Glad you got it sorted! :wink:

But, would you be able to E-Mail Sparkfun and tell them it wasn’t programmed properly?

7

Good call.