serial lcd with 16f628

[Bruce]

24608 will give you 19200, driven, inverted, even parity, but I doub't you're going to get solid results with the internal 4MHz osc.

Are you sure the serial LCD you're using requires "even" parity? You might want to try 16416 for 19200, driven, inverted, no parity? I've never used the Matrix Orbital serial LCD's, but the ones I have used require no parity.

The internal 4MHz osc doesn't provide a stable clock for any timing critical stuff like serial communications, and, Serout2 probably isn't going to work reliably at 19200bps with a 4MHz clock (if it works at all).

See the **'s next to 9600 & 19200 in the Serin2/Serout2 Mode Examples chart with the note at the bottom stating ** Oscillator faster than 4MHz may be required?

Just assume it's never going to be 100% reliable with 4MHz at any data rate showing the **'s next to it.

The internal osc is for non timing critical apps. It will drift & it's not always super precise to begin with on the older 16F62x series. Newer parts with 1% internal oscillators normally work really well, but not some of the older series.

The internal osc isn't a good option for "reliable" serial comms for sure, and definitely not for data rates that are already marginal at 4MHz.

You can use DEBUG for 19200bps with a 4MHz osc, but it may or may not be reliable with the internal osc.

DEFINE OSC 4
DEFINE DEBUG_REG PORTA
DEFINE DEBUG_BIT 3
DEFINE DEBUG_BAUD 19200
DEFINE DEBUG_MODE 1 '1=inverted, 0 = true

how do i change the internal osc of the 16f628?

Not sure what you mean by this. You can switch from the default 4MHz to 37kHz by clearing PCON.3.

If you want to use an external crystal VS the internal osc, then see Melanies thread here http://www.picbasic.co.uk/forum/showthread.php?t=543

and if i change it, do i need to change the baud #???

No. You should use whatever baud rate the LCD data sheet states. Just be sure to use an oscillator speed that supports the baud rate, or switch to another command that supports the baud rate at the osc frequency you're using like the DEBUG example above.

[dragons_fire]

thanks again. in my last post i thought that the internal osc could be changed, but then i realized that it wont go above 4mhz anyways... i changed to a 10.000mhz external and changed the code a bit, and it seems close, but its still not working, and im still not sure what im doing wrong... im getting a lot more digits displayed on the screen, and it displays every 2 seconds like it should from the code.


cmcon = 7
TRISA = %00000000
TRISB = %00001000

lcd VAR PORTA.3
baud CON 24608

Pause 4000

start:
SerOut2 lcd, baud,["hello world"]
Pause 2000
GoTo start
End

thanks for all the help
dan

[Bruce]

Insert DEFINE OSC 10 & be sure to set HS in config word.

[dragons_fire]

im probably sounding like an idiot now, but i just cant seem to get it to work and i have been trying for 3 days now...

i really apreciate the help.

@ DEVICE HS_OSC
DEFINE OSC 10
cmcon = 7
TRISA = %00000000
TRISB = %00001000

lcd VAR PORTA.3
baud CON 16416 '24608 16416

Pause 2000

start:

SerOut2 lcd, baud,["Hello World"]
Pause 2000
GoTo start
End


thanks
dan

[Bruce]

Do you have a link to the data sheet for this LCD?

[dragons_fire]

here is the link to the datasheet...

http://www.bipom.com/lcds/manuals/lcd2041.pdf

thanks for the help...

danny

[Bruce]

Is the protocol select jumper set for TTL or RS232?

If it's setup for RS232 then you should be able to talk to it with the Matrix uProject software. If not, check your comms wiring.

If it's setup for TTL then you should be able to use the PIC with inverted serial.

Have you tried resetting it to factory defaults? Might not be a bad idea just so you know it's at a specific baud rate.

Do you have a common ground between the LCD & PIC power supplys?