Файл: Microcontroller Programming. Thi Micro Chip PIC (Julio Sanchez, 2007).pdf
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Chapter 13 |
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1 = on, 0 = off |
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|____ Display on/off |
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1 = on, 0 = off |
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|____ COMMAND BIT |
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movwf |
PORTB |
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call |
pulseE |
;pulseE and |
delay |
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;***********************| |
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; DISPLAY AND CURSOR ON | |
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;***********************| |
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movlw |
0x0e |
; 0 0 0 0 |
1 |
1 1 0 (DISPLAY ON/OFF) |
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| | |___ Blink character |
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1 = on, 0 = off |
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| |___ Cursor on/off |
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1 = on, 0 = off |
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|____ Display on/off |
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1 = on, 0 = off |
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|____ COMMAND BIT |
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movwf |
PORTB |
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call |
pulseE |
;pulseE and |
delay |
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;***********************| |
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ENTRY MODE SET |
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;***********************| |
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movlw |
0x06 |
; 0 0 0 0 |
0 |
1 1 0 (ENTRY MODE SET) |
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| | |___ display shift |
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1 = shift |
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0 = no shift |
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| |____ increment mode |
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1 = left-to-right |
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0 = right-to-left |
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|___ COMMAND BIT |
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movwf |
PORTB |
;00000110 |
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call |
pulseE |
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;***********************| |
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; CURSOR/DISPLAY SHIFT |
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;***********************| |
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movlw |
0x14 |
; 0 0 0 1 |
0 |
1 0 0 (CURSOR/DISPLAY |
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SHIFT) |
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| |_|___ don’t care |
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|_|__ cursor/display shift |
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00 = cursor shift left |
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01 = cursor shift right |
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10 = cursor and display |
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shifted left |
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11 = cursor and display |
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LCD Interfacing and Programming |
311 |
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shifted right |
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|___ COMMAND BIT |
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movwf |
PORTB |
;0001 |
1111 |
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call |
pulseE |
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;***********************| |
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; |
CLEAR DISPLAY |
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;***********************| |
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movlw |
0x01 |
; 0 0 |
0 0 0 0 0 1 (CLEAR DISPLAY) |
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|___ COMMAND BIT |
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movwf |
PORTB |
;0000 |
0001 |
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; |
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call |
pulseE |
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call |
delay_5ms |
;delay 5 milliseconds after |
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init
return ;************************************************************ ; DELAY AND PULSE PROCEDURES ;************************************************************ ;=======================
;Procedure to delay
;42 microseconds ;======================= delay_125mcs
movlw |
D’42’ |
; Repeat 42 machine cycles |
movwf |
count1 |
; Store value in counter |
repeat |
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decfsz |
count1,f |
; Decrement counter |
goto |
repeat |
; Continue if not 0 |
return |
; End of delay |
;=======================
;Procedure to delay
;5 milliseconds ;======================= delay_5ms
movlw |
D’41’ |
; Counter = 41 |
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movwf |
count2 |
; Store in variable |
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delay |
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call |
delay_125mcs |
; Delay |
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decfsz |
count2,f |
; 40 times = 5 milliseconds |
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goto |
delay |
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return |
; End of delay |
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;======================== |
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; |
pulse E line |
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;======================== |
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pulseE |
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bsf |
PORTA,E_line |
;pulse E line |
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bcf |
PORTA,E_line |
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312 |
Chapter 13 |
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call |
delay_125mcs |
;delay 125 microseconds |
return |
;=============================
;long delay sub-routine
;(for debugging) ;============================= long_delay
movlw |
D’200’ |
; w = 200 decimal |
movwf |
J |
; J = w |
jloop: |
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movwf |
K |
; K = w |
kloop: |
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decfsz |
K,f |
; K = K-1, skip next if zero |
goto |
kloop |
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decfsz |
J,f |
; J = J-1, skip next if zero |
goto |
jloop |
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return |
;=============================
;LCD display procedure ;=============================
;Sends 16 characters from PIC buffer with address stored
;in variable pic_ad to LCD line previously selected display16:
;Set up for data
bcf |
PORTA,E_line |
; E line low |
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bsf |
PORTA,RS_line |
; RS line low for control |
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call |
delay_125mcs |
; Delay |
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; Set up counter for 16 characters |
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movlw |
D’16’ |
; |
Counter = 16 |
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movwf |
count3 |
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; Get display address from local variable pic_ad |
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movf |
pic_ad,w ; |
First display RAM address to W |
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movwf |
FSR |
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W to FSR |
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getchar: |
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movf |
INDF,w |
; |
get character from display RAM |
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; |
location pointed to by file select |
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; |
register |
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movwf |
PORTB |
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call |
pulseE |
;send data to display |
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; Test for 16 characters displayed |
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decfsz |
count3,f |
; Decrement counter |
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goto |
nextchar ; |
Skipped if done |
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return |
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nextchar: |
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incf |
FSR,f |
; |
Bump pointer |
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goto |
getchar |
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;========================
LCD Interfacing and Programming |
313 |
;blank buffer ;========================
;Procedure to store 16 blank characters in PIC RAM
;buffer starting at address stored in the variable
;pic_ad
blank16: |
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movlw |
D’16’ |
; Set up counter |
movwf |
count1 |
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movf |
pic_ad,w ; First PIC RAM address |
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movwf |
FSR |
; Indexed addressing |
movlw |
0x20 |
; ASCII space character |
storeit: |
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movwf |
INDF |
; Store blank character in PIC |
RAM |
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; buffer using FSR register |
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decfsz |
count1,f |
; Done? |
goto |
incfsr |
; no |
return |
; yes |
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incfsr: |
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incf |
FSR,f |
; Bump FSR to next buffer |
space |
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goto |
storeit |
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;========================
;Set Address register
;to LCD line 1 ;========================
;ON ENTRY:
;Address of LCD line 1 in constant LCD_1
line1:
bcf |
PORTA,E_line |
; E line low |
bcf |
PORTA,RS_line |
; RS line low, set up for |
control |
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call |
delay_125mcs |
; delay 125 microseconds |
; Set to second display line |
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movlw |
LCD_1 |
; Address and command bit |
movwf |
PORTB |
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call |
pulseE |
; Pulse and delay |
; Set RS line for data |
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bsf |
PORTA,RS_line |
; Set up for data |
call |
delay_125mcs |
; Delay |
return |
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;========================
;Set Address register
;to LCD line 2 ;========================
;ON ENTRY:
;Address of LCD line 2 in constant LCD_2