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Dependents: MAXREFDES131_Qt_Demo MAX32630FTHR_iButton_uSD_Logger MAX32630FTHR_DS18B20_uSD_Logger MAXREFDES130_131_Demo ... more
OneWire_Masters/GPIO/owlink.asm
- Committer:
- IanBenzMaxim
- Date:
- 2016-03-29
- Revision:
- 28:057bb14d3cee
File content as of revision 28:057bb14d3cee:
PROC_CLOCK_MHZ EQU 24 ; Processor clock in MHz
OVERHEAD_TUNING EQU 21 ; Fraction where OverheadTime(us) = OVERHEAD_TUNING / PROC_CLOCK_MHZ
; Make PROC_CLOCK_MHZ and OVERHEAD_TUNING divisible by PROC_CYCLES_PER_LOOP for best results
PIPELINE_REFILL_PROC_CYCLES EQU 1 ; ARM specifies 1-3 cycles for pipeline refill following a branch
PROC_CYCLES_PER_LOOP EQU (2 + PIPELINE_REFILL_PROC_CYCLES)
LOOPS_PER_US EQU (PROC_CLOCK_MHZ / PROC_CYCLES_PER_LOOP) ; Number of loop passes for a 1 us delay
LOOPS_REMOVED_TUNING EQU (OVERHEAD_TUNING / PROC_CYCLES_PER_LOOP)
SECTION owlink : CODE
; void ow_usdelay(unsigned int time_us)
PUBLIC ow_usdelay
ow_usdelay:
mov R1, #LOOPS_PER_US
mul R0, R0, R1
sub R0, R0, #LOOPS_REMOVED_TUNING
loop:
subs R0, R0, #1
bne loop
bx R14
END