Oskar Weigl / Mbed 2 deprecated LED_for_hackspace

LED screen driver build for hackspace.

Dependencies:   mbed

frameout.s@1:1af5060b2a34, 2012-02-29 (annotated)

Committer:
madcowswe
Date:
Wed Feb 29 17:09:46 2012 +0000
Revision:
1:1af5060b2a34
Parent:
0:f16a1d69a386 

        

        
Who changed what in which revision?

        

            
                
UserRevisionLine numberNew contents of line

            
            


madcowswe

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   AREA framefunc, CODE, READONLY





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; Export my_asm function location so that C compiler can find it and link





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    EXPORT frameout





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frameout





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; r0 - dsVal array base address





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; r1 - data array base address





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; r2 - base address for port 0





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; r3 - loop counter





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; r4 - sclk bitmask





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; r5 - RGB channels bitmask





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; r6 - data reg 1





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; r7 - data reg 2





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; r8 - temporary value holding intensity info (used as an offset into dsVal array)





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; Save state





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    PUSH {R4, R5, R6, R7, R8}





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; Load GPIO Port 0 base address in register R6 





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    LDR     R2, =0x2009C000 ; GPIO port 0 base address





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; R3 - loop counter





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    MOV     R3, #256





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; sclk mask





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    MOV     R4, #0x00010000 ; sclk bitmask





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; RGB channels mask





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    MOV     R5, #0x03800000 ; bitmask for RGB bits





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LOOP





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;NOTE clocking swapped due to inverter used for logic levels|





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    ;STR     R4, [R2, #0x18] ; setting clock high





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    STR     R4, [R2, #0x1C] ; cleark clk to clock in data (negative edge)





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    STR     R5, [R2, #0x1C] ; clear RGB via FIOCLEAR





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    ; R channel





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    LDRB     R8, [R1], #1 ; read data word (0-255 intensity) and post-increment array pointer to point to next word in data





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    LDRB     R6, [R0, R8] ; loading on/off state from dsVal, pointed to by offset equal to intensity of data





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    ; G channel  





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    LDRB     R8, [R1], #1 ; read data word (0-255 intensity) into R8 and post-increment to point to next word in data





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    LDRB     R7, [R0, R8] ; loading on/off state from dsVal, pointed to by offset equal to intensity of data





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    AND     R7, R7, #0x2 ; pick blue channel bit





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    ORR     R6, R7, R6, lsr #7 ; store RG bits in R6 with clever stuff in R chan





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    ; B channel





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    LDRB     R8, [R1], #1 ; read data word (0-255 intensity) into R8 and post-increment to point to next word in data





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    LDRB     R7, [R0, R8] ; loading on/off state from dsVal, pointed to by offset equal to intensity of data    





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    AND     R7, R7, #0x4 ; pick green channel bit





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    ; writing to output





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    ORR     R6, R6, R7 ; RGB bits in R6





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    MOV     R6, R6, lsl #23 





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    STR     R6, [R2,#0x18] ; FIOSET on/off for LED





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    SUBS    R3, R3, #0x1 ; decrement loop counter





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    STR     R4, [R2, #0x18] ; setting clock high





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    BNE     LOOP





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    POP {R4, R5, R6, R7, R8}





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    BX      LR





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    END