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There is lots of stuff on this topic, and I have looked at lots, but I fi=
nd=20
it bewilderingly inconsistent. Finally, I decided to use Microchip AN587 =
as=20
my guide.

I have assembler programmed an 18F452 to initialize a Powertip PC1602F 16=
X2=20
display, which I believe to be compatible with the HD44780. I use the 4-b=
it=20
interface. I have tested it by running power-up initialization, and then=20
sending a 'T'. However, it doesn't work, and I am really at a loss to kno=
w=20
what is wrong.

I wonder if anyone who has programmed such interfaces would mind having a=
=20
look at the following overview of the operation of my code? An experience=
d=20
person could perhaps spot immediately what may take me hours and hours to=
=20
find (yes, I am a noob).

Phil

*************************************************************************
PC1602F LCD Display Module Initialisation
*************************************************************************
I assumed that power on to the PC1602F does not comply with
the specification for proper power-on reset. Therefore initialization
by instruction is necessary. Procedure is as Microchip AN587.

                       RS  R/W  DB7 DB6 DB5 DB4
Power on
Wait 20mS
Send              0       0       0       0       1       1   (0x03) =20
Function Set 8-bit I/F
Wait 5mS
Send              0       0       0       0       1       1   (0x03) =20
Function Set 8-bit I/F
Wait 0.2mS
Send              0       0       0       0       1       1  (0x03) =20
Function Set 8-bit I/F
Wait 5mS
Send              0       0       0       0       1       0  (0x02) =20
Function Set 4-bit I/F
Wait 5mS

>From here on commands are 2 nibbles in quick sequence

Send              0       0       0       0       1       0  (0x02) =20
Function Set - Nibble 1
NO WAIT (strictly a few hundred nS)
Send              0       0       1       0       0       0  (0x08)  Nibb=
le=20
2 - 4-bit I/F,
                                                                         =
   =20
            2-line display, 5X7 chars.
Wait 1mS
Send              0       0       0       0       0       0  (0x00)  Disp=
lay=20
OFF - Nibble 1
NO WAIT (strictly a few hundred nS)
Send              0       0       1       0       0       0  (0x08)  Nibb=
le=20
2

Wait 1mS
Send              0       0       0       0       0       0   (0x00) =20
Display ON - Nibble 1
NO WAIT (strictly a few hundred nS)
Send              0       0       0       1       0       1   (0x05)  Nib=
ble=20
2

Wait 1mS
Send              0       0       0       0       0       0   (0x00)  Ent=
ry=20
Mode Set - Nibble 1
NO WAIT (strictly a few hundred nS)
Send              0       0       0       1       1       0  (0x06)  Nibb=
le=20
2 - Incr cursor
                                                                         =
   =20
            no display shift.
Wait 1mS

Now display is ready to receive characters.
To test simply send a single character ('T'):

Send              1       0       0       1       0       1  (0x25)  MS=20
nibble - write 'T'
NO WAIT (strictly a few hundred nS)
Send              1       0       0       1       0       0  (0x24)  LS=20
nibble - write 'T'

_________________________________________________________________
Windows Live=99 Messenger has arrived. Click here to download it for free=
!=20
http://imagine-msn.com/messenger/launch80/?locale=3Den-gb


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