Graphical Displays with PBP3

[rocket_troy]

Hi Richard,
Ordered a couple of st7920 displays for this and in the mean time I'm revisiting the Nokia display. 1 question: you're driving the 18F26K22 @64MHz for the sample codes; is that necessary? Can I drive the display using the same processor at, say, 16 MHz?

Thanks,

Troy

[richard]

1 question: you're driving the 18F26K22 @64MHz for the sample codes; is that necessary? Can I drive the display using the same processor at, say, 16 MHz?

no not essential any speed will work, its just slower. the hw 12c / spi speeds can be tweaked in some cases to compensate

[rocket_troy]

Hi Richard,
I've received my "st7920" displays from China (at least they're supposed to be) but I can't get anything from them from running your original code attachments in post #26. I haven't tried any of the code in #27 yet as I'm having problems with the "st7920.pbpmod" code having duplicate subroutines???
Anyway, can you possibly post a link or example of the wiring to this display. So far, I've connected all the 4 data lines, E bit, RS & RW bits to the declared PortB pins in your code. I've connected the V0 pin via a 10K pot and I've pulled up the serial/parallel selection pin to parallel selection and of course connected the power rails.

Thanks,

Troy

[richard]

for parallel i/f the connections are as defined
'LCD defines begin here
' DEFINE LCD_BITS 4 'defines the number of data interface lines (4 or 8)
' DEFINE LCD_DREG PORTB 'defines the port where data lines are connected to
' DEFINE LCD_DBIT 0 'defines the position of data lines for 4-bit interface (0 or 4)
' DEFINE LCD_RSREG PORTB 'defines the port where RS line is connected to
' DEFINE LCD_RSBIT 6 'defines the pin where RS line is connected to
' DEFINE LCD_EREG PORTB 'defines the port where E line is connected to
' DEFINE LCD_EBIT 4 'defines the pin where E line is connected
' DEFINE LCD_COMMANDUS 1500 'defines the delay after LCDOUT statement
' DEFINE LCD_DATAUS 60 'delay in micro seconds
' DEFINE LCD_RWREG PORTB ' LCD read/write port
' DEFINE LCD_RWBIT 5 ' LCD read/write pin bit
' 'END of LCD DEFINES

for serial i/f the connections are the mssp sdi sdo sck pins plus what you pick for st7920_cs
the st7920_rst pin was not required in my tests.

for a 26k22 i used
'spi pins used
'st7920_rst var latc.0
st7920_cs var latc.1
'st7920_sck is latc.3
'st7920_sdi is latc.4
'st7920_sdo is latc.5

I'm having problems with the "st7920.pbpmod" code having duplicate subroutines???

there is no problem pbp just doesn't understand conditional compilation, ignore the warnings

[rocket_troy]

there is no problem pbp just doesn't understand conditional compilation, ignore the warnings

Maybe it's because I thought I needed to compile that include file (on its own) where I probably don't?

Anyway... hmmm... I'll recheck everything and maybe try the serial option if I can't get the parallel working. So far I can't see anything I was doing wrong.

Cheers,

Troy

[richard]

Maybe it's because I thought I needed to compile that include file (on its own)

include files will seldom if ever compile on their own

[rocket_troy]

include files will seldom if ever compile on their own

Cool. I think the parallel version did which probably gave me the wrong assumptions. Anyway... couldn't get the parallel option working after trying both displays and throwing everything at it. I'm guessing there was a jumper fuse on the display that needed soldering closed to configure the data lines from 8 to 4, but I couldn't find any datasheet for the display so gave up that and went to serial. Took a bit of head scratching to match up the I2C lines to completely different labelled pads on the display, and then I finally got something from the display - a bunch of plain (non graphical looking) 1s and 0s. Took me 5-10 mins to figure out that's actually what was supposed to be there for the serial code - I was expecting demo graphics and large text - but that simply required copying over that stuff from the parallel code.
So, good stuff again Richard. Hats off and thanks again for the assistance.

Cheers,

Troy