178 lines
3.5 KiB
ArmAsm
178 lines
3.5 KiB
ArmAsm
.file "main.S"
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#include <msp430g2553.h>
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#define PC r0
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#define SP r1
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#define SR r2
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.section ".rodata","a"
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screendata:
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.byte 0x00
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.byte 0x01
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.byte 0x02
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.byte 0x03
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screendataend:
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.byte 0xff
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red:
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colors1:
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.byte 0b01001111
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colors2:
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.byte 0b01000111
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colors3:
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.byte 0b01000011
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.byte 0
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blue:
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.byte 0b11001111
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.byte 0b11000111
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.byte 0b11000011
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.byte 0
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green:
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.byte 0b10001111
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.byte 0b10000111
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.byte 0b10000011
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.byte 0
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;; .text is the name of the section, it is a hint for the linker to
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;; allocate the section
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;; ax: a means allocatable by linker, x means executable
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;; @progbits is a hint for the linker to allocate this section into
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;; program memory (flash)
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.section ".text","ax",@progbits
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_start:
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;; disable watchdog
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mov.w #WDTPW|WDTHOLD,&WDTCTL
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;; configure clock system to the highest frequency
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mov.b #DCO0|DCO1|DCO2,&DCOCTL
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mov.b #XT2OFF|RSEL0|RSEL1|RSEL2|RSEL3,&BCSCTL1
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mov.b #0,&BCSCTL2
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mov.b #0,&BCSCTL3
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;; initialize stack pointer with value from linker
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mov.w #__stack, SP
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mov.w #0xaaaa, r7
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mov.w #0x5555, r8
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init:
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;; configuration of GPIO Ports
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mov.b #BIT0|BIT1|BIT2,&P1DIR
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mov.b #BIT1|BIT4,&P2DIR
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mov.b #BIT1|BIT4,&P2SEL
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;; timer configuration
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;; configure and stop timer
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;; cycle time is 56.25ns
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mov.w #ID_0|MC_0|TACLR|TASSEL_2,&TA1CTL
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;; 2.0us
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mov.w #45,&TA1CCR0
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;; a bit less
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mov.w #10,&TA1CCR1
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mov.w #22,&TA1CCR2
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;; configure output mode for TA0.1
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mov.w #CCIE,&TA1CCTL0
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mov.w #OUTMOD_7,&TA1CCTL1
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mov.w #OUTMOD_7,&TA1CCTL2
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;; initialize bit-counter for isr
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mov.b #0x01,r6
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;; initialize isr-sync register
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mov.b #0x00,r4
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;; screen data start/next into r7
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mov.w #screendata, r7
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;; screen data end into r8
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mov.w #screendataend, r8
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;; load first screen data value into r5
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mov.b @r7,r5
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inc.w r7
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;; start timer in up mode
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bis.w #MC0,&TA1CTL
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;; enable interrupts
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eint
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;; r4: synchronization between mainloop and isr
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;; r5: data byte to be handled by isr
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mainloop:
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;; prepare next byte to handle by isr
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cmp.w r7,r8
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jnz mainloop_prepare_next_byte
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mov.w &screendata,r7
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mainloop_prepare_next_byte:
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mov.b @r7,r9
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inc.w r7
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mainloop_wait_for_isr:
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;; check bit0 in sync register
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bit #0x01,r4
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jz mainloop_wait_for_isr
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;; load data
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mov.b r9,r5
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mov.b #0x00,r4
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;; signal reload
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bis #BIT2,&P1OUT
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bic #BIT2,&P1OUT
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;; continue
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jmp mainloop
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; --- timer isr ---
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;; r6: exclusively used by isr as bit-counter
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timer1_a0_isr:
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;; func begin marker
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bis #BIT0,&P1OUT
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;; check isr idle bit
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bit #BIT1,r4
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jnz timer1_a0_isr_exit
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;; shift msb of data register r5 into carry flag and set or reset P1.1 accordingly
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rla.b r5
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jnc timer1_a0_isr_false_bit
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bis #BIT1,&P1OUT
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jmp timer1_a0_isr_end
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timer1_a0_isr_false_bit:
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bic #BIT1,&P1OUT
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;; shift bit-counter, after eight shifts signal byte done and reset bit-counter
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timer1_a0_isr_end:
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rla.b r6
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jnc timer1_a0_isr_exit
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;; reset bit-counter
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mov.b #0x01,r6
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;; signal byte done
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mov.b #0x01,r4
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timer1_a0_isr_exit:
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;; func end marker
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bic #BIT0,&P1OUT
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reti
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;timer0_a1_isr:
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; reti
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; --- interrupt vectors ---
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; .section "__interrupt_vector_9","ax",@progbits
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; .word timer0_a1_isr
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.section "__interrupt_vector_14","ax",@progbits
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.word timer1_a0_isr
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;; .resetvec comes from linker
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.section ".resetvec","ax",@progbits
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.word _start
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.end
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