?? tut7_3a.asm
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;Tutorial 7_3a
;Serial routines - display received bytes on LCD
;Nigel Goodwin 2003
LIST p=16F876 ;tell assembler what chip we are using
include "P16F876.inc" ;include the defaults for the chip
ERRORLEVEL 0, -302 ;suppress bank selection messages
__config 0x393A ;sets the configuration settings (oscillator type etc.)
cblock 0x20 ;start of general purpose registers
count ;used in looping routines
count1 ;used in delay routine
counta ;used in delay routine
countb ;used in delay routine
templcd ;temp store for 4 bit mode
templcd2
lcdtmp
Xmit_Byte ;holds byte to xmit
Rcv_Byte ;holds received byte
Bit_Cntr ;bit counter for RS232
Delay_Count ;delay loop counter
endc
LCD_PORT Equ PORTB
LCD_TRIS Equ TRISB
LCD_RS Equ 0x04 ;LCD handshake lines
LCD_RW Equ 0x06
LCD_E Equ 0x07
SER_PORT Equ PORTC
SER_TRIS Equ TRISC
SER_IN Equ 0x07
SER_OUT Equ 0x06
org 0x0000
BANKSEL ADCON1
movlw 0x06
movwf ADCON1
BANKSEL PORTA ;turn analogue inputs off
Initialise clrf count
clrf PORTA
clrf PORTB
call SER_INIT ;initialise serial port
call LCD_Init
Loop call Rcv_RS232
call LCD_Char
goto Loop
;Serial routines
SER_INIT
BSF STATUS, RP0 ;select bank 1
BCF SER_TRIS, SER_OUT ;set B6 as an output
BSF SER_TRIS, SER_IN ;set B7 as an input
BCF STATUS, RP0 ;select bank 0
BSF SER_PORT, SER_OUT ;set SER_OUT high
RETURN
XMIT_RS232 MOVWF Xmit_Byte ;move W to Xmit_Byte
MOVLW 0x08 ;set 8 bits out
MOVWF Bit_Cntr
BCF SER_PORT, SER_OUT
CALL Bit_Delay
Ser_Loop RRF Xmit_Byte , f ;send one bit
BTFSS STATUS , C
BCF SER_PORT, SER_OUT
BTFSC STATUS , C
BSF SER_PORT, SER_OUT
CALL Bit_Delay
DECFSZ Bit_Cntr , f ;test if all done
GOTO Ser_Loop
BSF SER_PORT, SER_OUT
CALL Bit_Delay
RETURN
Rcv_RS232 BTFSC SER_PORT, SER_IN ;wait for start bit
GOTO Rcv_RS232
CALL Start_Delay ;do half bit time delay
BTFSC SER_PORT, SER_IN ;check still in start bit
GOTO Rcv_RS232
MOVLW 0x08 ;set up to read 8 bits
MOVWF Bit_Cntr
CLRF Rcv_Byte
Next_RcvBit CALL Bit_Delay
BTFSS SER_PORT, SER_IN
BCF STATUS , C
BTFSC SER_PORT, SER_IN
BSF STATUS , C
RRF Rcv_Byte , f
DECFSZ Bit_Cntr , f ;test if all done
GOTO Next_RcvBit
CALL Bit_Delay
MOVF Rcv_Byte, W
RETURN
Start_Delay MOVLW 0x3D
MOVWF Delay_Count
Start_Wait NOP
DECFSZ Delay_Count , f
GOTO Start_Wait
RETURN
Bit_Delay MOVLW 0x7A
MOVWF Delay_Count
Bit_Wait NOP
DECFSZ Delay_Count , f
GOTO Bit_Wait
RETURN
;End of serial routines
;LCD routines
;Initialise LCD
LCD_Init call LCD_Busy ;wait for LCD to settle
movlw 0x20 ;Set 4 bit mode
call LCD_Cmd
movlw 0x28 ;Set display shift
call LCD_Cmd
movlw 0x06 ;Set display character mode
call LCD_Cmd
movlw 0x0c ;Set display on/off and cursor command
call LCD_Cmd ;Set cursor off
call LCD_Clr ;clear display
retlw 0x00
; command set routine
LCD_Cmd movwf templcd
swapf templcd, w ;send upper nibble
andlw 0x0f ;clear upper 4 bits of W
movwf LCD_PORT
bcf LCD_PORT, LCD_RS ;RS line to 1
call Pulse_e ;Pulse the E line high
movf templcd, w ;send lower nibble
andlw 0x0f ;clear upper 4 bits of W
movwf LCD_PORT
bcf LCD_PORT, LCD_RS ;RS line to 1
call Pulse_e ;Pulse the E line high
call LCD_Busy
retlw 0x00
LCD_CharD addlw 0x30 ;add 0x30 to convert to ASCII
LCD_Char movwf templcd
swapf templcd, w ;send upper nibble
andlw 0x0f ;clear upper 4 bits of W
movwf LCD_PORT
bsf LCD_PORT, LCD_RS ;RS line to 1
call Pulse_e ;Pulse the E line high
movf templcd, w ;send lower nibble
andlw 0x0f ;clear upper 4 bits of W
movwf LCD_PORT
bsf LCD_PORT, LCD_RS ;RS line to 1
call Pulse_e ;Pulse the E line high
call LCD_Busy
retlw 0x00
LCD_Line1 movlw 0x80 ;move to 1st row, first column
call LCD_Cmd
retlw 0x00
LCD_Line2 movlw 0xc0 ;move to 2nd row, first column
call LCD_Cmd
retlw 0x00
LCD_Line1W addlw 0x80 ;move to 1st row, column W
call LCD_Cmd
retlw 0x00
LCD_Line2W addlw 0xc0 ;move to 2nd row, column W
call LCD_Cmd
retlw 0x00
LCD_CurOn movlw 0x0d ;Set display on/off and cursor command
call LCD_Cmd
retlw 0x00
LCD_CurOff movlw 0x0c ;Set display on/off and cursor command
call LCD_Cmd
retlw 0x00
LCD_Clr movlw 0x01 ;Clear display
call LCD_Cmd
retlw 0x00
Pulse_e bsf LCD_PORT, LCD_E
nop
bcf LCD_PORT, LCD_E
retlw 0x00
LCD_Busy
bsf STATUS, RP0 ;set bank 1
movlw 0x0f ;set Port for input
movwf LCD_TRIS
bcf STATUS, RP0 ;set bank 0
bcf LCD_PORT, LCD_RS ;set LCD for command mode
bsf LCD_PORT, LCD_RW ;setup to read busy flag
bsf LCD_PORT, LCD_E
swapf LCD_PORT, w ;read upper nibble (busy flag)
bcf LCD_PORT, LCD_E
movwf templcd2
bsf LCD_PORT, LCD_E ;dummy read of lower nibble
bcf LCD_PORT, LCD_E
btfsc templcd2, 7 ;check busy flag, high = busy
goto LCD_Busy ;if busy check again
bcf LCD_PORT, LCD_RW
bsf STATUS, RP0 ;set bank 1
movlw 0x00 ;set Port for output
movwf LCD_TRIS
bcf STATUS, RP0 ;set bank 0
return
;end of LCD routines
;Delay routines
Long_Delay
call Delay255
call Delay255
call Delay255
call Delay255
return
Delay255 movlw 0xff ;delay 255 mS
goto d0
Delay100 movlw d'100' ;delay 100mS
goto d0
Delay50 movlw d'50' ;delay 50mS
goto d0
Delay20 movlw d'20' ;delay 20mS
goto d0
Delay10 movlw d'10' ;delay 10mS
goto d0
Delay1 movlw d'1' ;delay 1mS
goto d0
Delay5 movlw 0x05 ;delay 5.000 ms (4 MHz clock)
d0 movwf count1
d1 movlw 0xE7
movwf counta
movlw 0x04
movwf countb
Delay_0 decfsz counta, f
goto $+2
decfsz countb, f
goto Delay_0
decfsz count1 ,f
goto d1
retlw 0x00
;end of Delay routines
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