Learning how to use USART

[mpgmike]

There is an initialization process to get LCDs to come on line. It usually isn't needed, but I ran into an instance like yours where everything suggested it SHOULD work, but it didn't. One of the HD44780 LCD Data Sheets outlined an initialization process. Here is what I use:

4-Wire

Init_LCD:
    RS = 0
'    LCD = $20
    DB7 = 0
    DB6 = 0
    DB5 = 1
    DB4 = 0
        En = 1
        pauseus 10
        En = 0
        pause 5
'    LCD = $20
    DB7 = 0
    DB6 = 0
    DB5 = 1
    DB4 = 0
        En = 1
        pauseus 10
        En = 0
        pauseus 160
'    LCD = $20
    DB7 = 0
    DB6 = 0
    DB5 = 1
    DB4 = 0
        En = 1
        pauseus 10
        En = 0
        pauseus 160
    LCD = $28
        gosub Send
    LCD = $10
        gosub Send
    LCD = $0C
        gosub Send
    LCD = $06
        gosub Send
    LCD = 1
        gosub Send
        pause 1
    LCD = $80
        gosub Send
    RS = 1
    pause 1
RETURN

For 8-wire:

Init_LCD:
    low RS
    PORTB = $30
        high En
        pauseus 4
        low En
        pause 5
    PORTB = $30
        high En
        pauseus 4
        low En
        pauseus 160
    PORTB = $30
        high En
        pauseus 4
        low En
        pauseus 160
    PORTB = $38
        gosub Send
    PORTB = $10
        gosub Send
    PORTB = $0C
        gosub Send
    PORTB = $06
        gosub Send
    PORTB = 1
        gosub Send
        pause 1
    PORTB = $80
        gosub Send
    high RS
    pause 1 
RETURN

Send:
    high En
    pauseus 8
    low En
    pause 1
return

Maybe this will help.

[richard]

The blinking LED on the transmitting PIC is working, and the LCD on the receiving PIC is working, but I'm not seeing any numbers being displayed.

given all things working display wise ,imho mike is leading you astray

tx unit:-

send = send + 1
hserout [send]

will send binary 0 to 9 , probably not the best idea but it is workable


ps weird baud rate


rx unit:-


hserin [dec data_in]
pause 5

will never work

1. its waiting for ascii numbers , the first non number will terminate routine
2. pause 5 why it serves no purpose and can cause framing errors


add this define
DEFINE HSER_CLROERR 1 ' Clear overrun error upon execution of every HSERIN command


rx unit:-
lcdout $fe, $94, dec data_in

if ok but it needs
hserin [data_in] to match data types

ps weird baud rate