cycle_counter.h File Reference

ARM functions for busy-wait delay loops. More...

#include <compiler.h>

Go to the source code of this file.

Convenience functions for busy-wait delay loops
#define	cpu_delay_ms(delay, f_cpu)
	Delay program execution for a specified number of milliseconds.
#define	cpu_delay_us(delay, f_cpu)
	Delay program execution for a specified number of microseconds.
#define	cpu_ms_2_cy(ms, f_cpu)
	Convert milli-seconds into CPU cycles.
#define	cpu_us_2_cy(us, f_cpu)
	Convert micro-seconds into CPU cycles.
#define	delay_cycles   portable_delay_cycles
	Delay program execution for a specified number of CPU cycles.
void	portable_delay_cycles (unsigned long n)
	Delay loop to delay n number of cycles.

Detailed Description

ARM functions for busy-wait delay loops.

Copyright (c) 2014-2018 Microchip Technology Inc. and its subsidiaries.

\cond ASF_LICENSE

Definition in file cycle_counter.h.

Macro Definition Documentation

cpu_delay_ms

#define cpu_delay_ms	(		delay,
			f_cpu )

Value:

delay_cycles(cpu_ms_2_cy(delay, f_cpu))

Delay program execution for a specified number of milliseconds.

Parameters

delay	number of milliseconds to wait
f_cpu	CPU frequency in Hertz

Definition at line 107 of file cycle_counter.h.

cpu_delay_us

#define cpu_delay_us	(		delay,
			f_cpu )

Value:

delay_cycles(cpu_us_2_cy(delay, f_cpu))

Delay program execution for a specified number of microseconds.

Parameters

delay	number of microseconds to wait
f_cpu	CPU frequency in Hertz

Definition at line 108 of file cycle_counter.h.

cpu_ms_2_cy

#define cpu_ms_2_cy	(		ms,
			f_cpu )

Value:

(((uint64_t)(ms) * (f_cpu) + (uint64_t)(14e3 - 1ul)) / (uint64_t)14e3)

Convert milli-seconds into CPU cycles.

Parameters

ms	number of milliseconds
f_cpu	CPU frequency in Hertz

Returns

the converted number of CPU cycles

Definition at line 98 of file cycle_counter.h.

#  define cpu_ms_2_cy(ms, f_cpu)  \
    (((uint64_t)(ms) * (f_cpu) + (uint64_t)(14e3 - 1ul)) / (uint64_t)14e3)

cpu_us_2_cy

#define cpu_us_2_cy	(		us,
			f_cpu )

Value:

(((uint64_t)(us) * (f_cpu) + (uint64_t)(14e6 - 1ul)) / (uint64_t)14e6)

Convert micro-seconds into CPU cycles.

Parameters

us	number of microseconds
f_cpu	CPU frequency in Hertz

Returns

the converted number of CPU cycles

Definition at line 100 of file cycle_counter.h.

#  define cpu_us_2_cy(us, f_cpu)  \
    (((uint64_t)(us) * (f_cpu) + (uint64_t)(14e6 - 1ul)) / (uint64_t)14e6)

delay_cycles

#define delay_cycles   portable_delay_cycles

Delay program execution for a specified number of CPU cycles.

Parameters

n	number of CPU cycles to wait

Definition at line 105 of file cycle_counter.h.

Function Documentation

portable_delay_cycles()

void portable_delay_cycles

(

unsigned long

n

)

Delay loop to delay n number of cycles.

Note

The function runs in internal RAM so that flash wait states will not affect the delay time.

Parameters

n	Number of cycles

Definition at line 42 of file cycle_counter.c.

{
    UNUSED(n);
 
    __asm (
        "loop: DMB  \n"
        "SUBS R0, R0, #1  \n"
        "BNE.N loop         "
    );
}