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Picaxe 7 Segment Display

This is the AQA version closing after June 2019. Visit the the version for Eduqas instead .

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Designing the Binary Data

This grid has two rows filled in as an example for version A below.
Note that you need a zero to make a segment come on.
You can use the grid for version B, but the example data is wrong.

Incomplete Code

Copy this code to the programming editor.
When you have wired up the hardware, test the code.
Finally, get the displays to count from 0 to 9.

; ===== Count from 0 to 9 (INCOMPLETE) =====
			
START:
        MOVW    0X08        ; 0
        CALL    SEG
        MOVW    0X3E        ; 1
        CALL    SEG
        MOVW    0X11        ; 2
        CALL    SEG
        
        JMP     START
        
; ======= SUBROUTINE ========
SEG:
        MOVWR   PORTB
        CALL    WAIT100MS
        CALL    WAIT100MS
        CALL    WAIT100MS
        RET
; ======= END SUBROUTINE ====

Wiring up the Display - Version A

There are two common Seven Segment Display pinouts. Use one of the next two diagrams as a guide.

If you are using the ENSFC board, you don't need current limiting resistors because these are built into the circuit board.

Wiring up the Display - Version B

AQA Simulator Version

CTRL+Click here to run the simulator.

Type in the code below or copy and paste it.
Click the "A" button to assemble the code (translate it into binary).
Click the "S" button to step through the program.
This code is very similar to the PICAXE version.
You need to write your own wait100ms subroutine.
Connect the seven segment displays to PORTB.
The control data is different for two reasons.
- The pin layout is different.
- Logic one is needed to light a segment.

; ===== This code has been tested =====
main:
    movw    0x7D            ; Display a Zero
    movwr   PORTB
    call    wait100ms       ; Delay 300mS
    call    wait100ms
    call    wait100ms
    movw    0x05            ; Display a One
    movwr   PORTB
    call    wait100ms       ; Delay 300mS
    call    wait100ms
    call    wait100ms
    movw    0x5B            ; Display a Two
    movwr   PORTB
    call    wait100ms
    call    wait100ms
    call    wait100ms

                            ; FINISH THIS        
    jmp main

wait100ms:
    NOP
    NOP
    RET