Testboard K4 configured for 628uart.asm
Function
This program sends an alive message and
then echoes characters received from a terminal via RS232.
Hardware
The testboard K4 is set up with reset
circuit and a ST232 (or MAX232) for RS232 communication.
Software in assembler
;*******************************************************************
; Function: Sends alive
message, then echoes characters at 9600 bps
; Processor: PIC16F628 at
4 MHz using internal RC oscillator
; Hardware: Testboard
K4
; Filename:
628uart.asm
; Author:
Lars Petersen, oz1bxm@qsl.net
; Website:
www.qsl.net/oz1bxm/PIC/pic.htm
; Credit:
Tony Nixon's test program at
;
www.piclist.com/techref/microchip/16f877/setup.htm
;*******************************************************************
LIST P=16F628, R=DEC ; Use the PIC16F628 and decimal system
#include "P16F628.INC" ; Include header file
__config _INTRC_OSC_NOCLKOUT & _LVP_OFF & _WDT_OFF & _PWRTE_ON & _BODEN_ON
CBLOCK
0x20
; Declare variable addresses starting at 0x20
dataL
ENDC
ORG
0x000 ;
Program starts at 0x000
;
;
--------------------------------
; SET ANALOG/DIGITAL INPUTS
PORT A
;
--------------------------------
;
movlw 7
movwf
CMCON
; CMCON=7 set comperators off
;
;
----------------
; INITIALIZE
PORTS
;
----------------
;
movlw b'00000000' ; set up
portA
movwf PORTA
movlw b'00000100' ; RB2(TX)=1 others
are 0
movwf PORTB
bsf STATUS,RP0 ; RAM PAGE 1
movlw 0xFF
movwf
TRISA
; portA all pins input
movlw b'11110010' ; RB7-RB4 and
RB1(RX)=input, others output
movwf TRISB
;
------------------------------------
; SET BAUD RATE TO COMMUNICATE
WITH PC
;
------------------------------------
; Boot Baud Rate = 9600, No
Parity, 1 Stop Bit
;
movlw
0x19
; 0x19=9600 bps (0x0C=19200 bps)
movwf SPBRG
movlw b'00100100' ; brgh = high
(2)
movwf
TXSTA
; enable Async Transmission, set brgh
bcf STATUS,RP0 ; RAM PAGE 0
movlw b'10010000' ; enable Async
Reception
movwf RCSTA
;
;
------------------------------------
; PROVIDE A SETTLING TIME
FOR START UP
;
------------------------------------
;
clrf dataL
settle decfsz
dataL,F
goto settle
movf RCREG,W
movf RCREG,W
movf
RCREG,W
; flush receive buffer
;
; ---------
; MAIN LOOP
; ---------
;
call
message
; send "16F628 alive"
loop call
receive
; wait for a char
call
send
; send the char
goto loop
;
;
-------------------------------------------
; RECEIVE CHARACTER FROM RS232
AND STORE IN W
;
-------------------------------------------
; This routine does not return
until a character is received.
;
receive btfss
PIR1,RCIF ; (5) check for
received data
goto receive
movf
RCREG,W
; save received data in W
return
;
;
-------------------------------------------------------------
; SEND CHARACTER IN W VIA
RS232 AND WAIT UNTIL FINISHED SENDING
;
-------------------------------------------------------------
;
send movwf
TXREG
; send data in W
TransWt bsf
STATUS,RP0 ; RAM PAGE
1
WtHere btfss
TXSTA,TRMT ; (1) transmission is
complete if hi
goto WtHere
bcf STATUS,RP0 ; RAM
PAGE 0
return
;
; -------
; MESSAGE
; -------
;
message movlw
'1'
call send
movlw '6'
call send
movlw 'F'
call send
movlw '6'
call send
movlw '2'
call send
movlw '8'
call send
movlw ' '
call send
movlw 'a'
call send
movlw 'l'
call send
movlw 'i'
call send
movlw 'v'
call send
movlw 'e'
call send
movlw 0x0D ; CR
call send
movlw 0x0A ; LF
call send
return
END
Remarks
The ST232 is used for RS232 communication.
An MAX232 can also be used. A simpler circuit can be set up using DS275,
see the homepage of
Wichit
Sirichote from Thailand.
A terminal program (HyperTerminal) is
set up for 9600 baud with 8 data bits, no parity, no flowcontrol and 1 stop
bit.
The alive message displayed in HyperTerminal
The same program written in C is here.
Download
Download
628art.zip containing
the source code in assembler and the hexfile.
Credit
Tony Nixon's UART test program at
http://www.piclist.com/techref/microchip/16f877/setup.htm
was my source for the above program. Thanks!
Interested:
Questions:
Comments: