How to use 74HC595 with Pic Basic Pro

node said:

I too will like help with this IC. I am a Bascom AVR user; I will like to know how to go about making a data table using Bascom AVR, to make my 7 segment Led light.

I have two seperate Led connected to the shift regiter connected to a AT90S2313, using a 10Mhz crystal.

This is how it is connected. I am using Common Cathode Leds and using NPN transistors.

http://home.wanadoo.nl/electro1/avr... are the transistors connection to the Leds http://www.blitzlogic.com/7seg_90.GIF

any help would be appreciated.

Click to expand...

.equ	 LOW = r21
.equ	HIGH = r22
.equ	STCP = 2	;storage clock
.equ	SHCP = 3	;shift clock
.equ	DS = 4		;data bit


Update_display_LOW:
	ldi	ZL,LOW (table*2)
	ldi	ZH,HIGH(table*2)
	add	ZL, LOW		;add offset to base
	lpm			;read data to r0          
         
	mov	r18,R0
	rcall	ShiftByte	;send byte to 74HC595
	cbi    PORTB, 1	; turn on low display (ones)	
	ret
;----------------------------------------------------------
Update_display_HIGH:
	ldi	ZL,LOW (table*2)
	ldi	ZH,HIGH(table*2)
	add	ZL, HIGH	;add offset to base
	lpm			;read data to r0
	
	mov	r18,R0
	rcall	ShiftByte	;send byte to 74HC595

        cbi    PORTB, 0   	; turn on high display (tens)
	ret
;----------------------------------------------------------
Table:
.db 0b00111111,0b00000110,0b01011011,0b01001111
.db 0b01100110,0b01101101,0b01111100,0b00000111
.db 0b01111111,0b01100111
;----------------------------------------------------------
ShiftByte:
	  ldi    r19, 8    	; 8 bits to shift
ShiftLoop:
	  sbrc   r18, 0       ; skip if bit 0 = clr
          sbi    PORTB, DS    ; else send a 1
          sbrs   r18, 0       ; send a 0
          cbi    PORTB, DS    ; 
          sbi    PORTB, SHCP  ; pulse shift clock
          lsr    r18          ; next bit
          cbi    PORTB, SHCP  ; end shift clock pulse
          dec    r19          ; one less bit
           brne  ShiftLoop    ; loop for 8 bits

          sbi    PORTB, STCP  ; pulse storage clock high
          nop                 ; 
          cbi    PORTB, STCP  ; then return low
          ret                 ; 
;----------------------------------------------------------

	rcall	ShiftByte	;send byte to 74HC595

out PORTB,r18       ;of course you will have to change the other pins already using portb.

Fragrance said:

hi

here you go

Click to expand...

ctownsend said:

here's a bit of code that will work with the 2313. The 2313 supports the lpm instruction so you don't have to store the table in eeprom. You can store the table in the flash and just use the lpm instruction to fetch the correct byte.

If your pinout is the same as the one here:
**broken link removed**

this will work for you (with some extra code for setting up ports, stack, etc.)

**SORRY, I don't do Bascom, asm only.***

Code:

.equ	 LOW = r21
.equ	HIGH = r22
.equ	STCP = 2	;storage clock
.equ	SHCP = 3	;shift clock
.equ	DS = 4		;data bit


Update_display_LOW:
	ldi	ZL,LOW (table*2)
	ldi	ZH,HIGH(table*2)
	add	ZL, LOW		;add offset to base
	lpm			;read data to r0          
         
	mov	r18,R0
	rcall	ShiftByte	;send byte to 74HC595
	cbi    PORTB, 1	; turn on low display (ones)	
	ret
;----------------------------------------------------------
Update_display_HIGH:
	ldi	ZL,LOW (table*2)
	ldi	ZH,HIGH(table*2)
	add	ZL, HIGH	;add offset to base
	lpm			;read data to r0
	
	mov	r18,R0
	rcall	ShiftByte	;send byte to 74HC595

        cbi    PORTB, 0   	; turn on high display (tens)
	ret
;----------------------------------------------------------
Table:
.db 0b00111111,0b00000110,0b01011011,0b01001111
.db 0b01100110,0b01101101,0b01111100,0b00000111
.db 0b01111111,0b01100111
;----------------------------------------------------------
ShiftByte:
	  ldi    r19, 8    	; 8 bits to shift
ShiftLoop:
	  sbrc   r18, 0       ; skip if bit 0 = clr
          sbi    PORTB, DS    ; else send a 1
          sbrs   r18, 0       ; send a 0
          cbi    PORTB, DS    ; 
          sbi    PORTB, SHCP  ; pulse shift clock
          lsr    r18          ; next bit
          cbi    PORTB, SHCP  ; end shift clock pulse
          dec    r19          ; one less bit
           brne  ShiftLoop    ; loop for 8 bits

          sbi    PORTB, STCP  ; pulse storage clock high
          nop                 ; 
          cbi    PORTB, STCP  ; then return low
          ret                 ; 
;----------------------------------------------------------

If your pinout changes, you simply have to modify the table.
If you are not using a shift register, all you have to do is replace the lines:

Code:

	rcall	ShiftByte	;send byte to 74HC595

with this:

Code:

out PORTB,r18       ;of course you will have to change the other pins already using portb.

It should work provided the pinout is the same as the one in shift register schematic (in the link above)
Good Luck

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how to use 74hc595

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