LCD Line3/4 DDRAM

musselmc · Mar 23, 2012

Hey,

I am trying to access the 3rd and 4th lines of a 16x4 LCD module.

datasheet:
https://www.electro-tech-online.com/custompdfs/2012/03/LCM-S01604DSF.pdf

According to this forum post:
https://www.electro-tech-online.com/threads/broken-4x20-lcd-hitachi-44780.33554/

line 3 is a continuation of line1, and line 4 is a continuation of line 2, and line 2 always begins at DDRAM 0x40... So for line 3 I have tried DDRAM address 0x10 (0x00 +16), and for line 4 I have tried DDRAM address 0x50 (0x40 + 16), but my characters aren't displayed for either.

If I set the DDRAM address as 0x40, my characters ARE displayed on line 2.

Any help would be appreciated.

ericgibbs · Mar 23, 2012

hi,
The 44780 Controller has Line addresses at 1,2,3,4
80h
C0h
90h
D0h

musselmc · Mar 23, 2012

I believe the COMMAND to set the DDRAM address is 1xxx xxxx (7 bits for the address), so the DDRAM addresses of 0x0, 0x40, 0x10, and 0x50, translate to the same commands as you've listed above. Those are the commands I am sending. Unless I am missing something here?

musselmc · Mar 23, 2012

musselmc said:
I believe the COMMAND to set the DDRAM address is 1xxx xxxx (7 bits for the address), so the DDRAM addresses of 0x0, 0x40, 0x10, and 0x50, translate to the same commands as you've listed above. Those are the commands I am sending. Unless I am missing something here?

WELL!... turns out I was making the changes to the .s file, but kept loading the old .s file to the micro. Problem solved.

Mike - K8LH · Mar 23, 2012

ericgibbs said:
The 44780 Controller has Line addresses at 1,2,3,4
80h
C0h
90h
D0h

Hi Eric,

Isn't it 20 characters per line on the 4x20 displays?

Code:

  line 1  128 + 0   (0x80 + 0x00)  DDRAM 0x00..0x13
  line 2  128 + 64  (0x80 + 0x40)  DDRAM 0x40..0x53
  line 3  128 + 20  (0x80 + 0x14)  DDRAM 0x14..0x27
  line 4  128 + 84  (0x80 + 0x54)  DDRAM 0x54..0x67

**broken link removed**

musselmc · Mar 23, 2012

I believe you're right Mike, my question was for 16x4 lines though...

Mike - K8LH · Mar 23, 2012

musselmc said:
I believe you're right Mike, my question was for 16x4 lines though...

I beg your pardon, Sir (and Eric). I've not seen one of those yet.

Cheerful regards, Mike

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