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problem with LCDDEMO — Parallax Forums

problem with LCDDEMO

TimHTimH Posts: 48
edited 2009-11-08 23:44 in Propeller 1
Hello

I'm still new to the Propeller and Spin but am working through some of the Object Exchange Objects.
I am trying to use the LCDDEMO to drive a standard 4 X 20 with a Hitachi HD44780 driver chip.
I found the connection diagram in the driver documentation was incorrect (data lines and RS/E reversed) and once I had changed that I was able to get something displayed but only on lines 1 and 3. Looking in the HD44780 data sheet it seems that the memory locations for the characters on line 3 continue from line 1.
ie Line 1 ends at address 93 and line 3 begins at address 94. It seems that the INIT routine in the LCDDEMO is not configuring the display for 4 lines correctly but I can't figure out in the PUB INIT in the LCDDEMO to make the corrections. Does anyone else have any experience with this object.

Thanks

Comments

  • AleAle Posts: 2,363
    edited 2009-11-08 07:48
    You only have to add an initialization command for 2 lines is $28. Add it at the end of the init routine if it is not there already. The good is that you can see on the display what you wrote... that means all connections and timings are correct.

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  • TimHTimH Posts: 48
    edited 2009-11-08 20:00
    Thanks Ale

    Yes I went in and changed the INIT in the LCDDEMO object from 6 to 40 ($28) and all working.
    I don't know if anyone else has had problems with this Object.
  • DonEduardoDonEduardo Posts: 54
    edited 2009-11-08 23:44
    Hmm, problem with the schematic?? Man, I happened to make my first attempt this weekend at getting a 2 line by 12 character 4-bit LCD working. Had lots of trouble until I tried this object in the Exchange: jm_lcd4_ez

    I had wired the d4-d7 pins using ascending Prop pins. This seemed to be the only driver that allowed me to do that. Now that you mention a problem with the schematic, I wonder if I'll be able to get this to work with the other drivers now. But no matter, that driver seems to do everything I need and is already configured for a 2 line display (just had to fix things a little for the 12 characters instead of the default of 16).
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