Paparazzi UAS  v5.15_devel-112-g521f3cf
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sys_time_arch.h
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23 
32 #ifndef SYS_TIME_ARCH_H
33 #define SYS_TIME_ARCH_H
34 
35 #include "mcu_periph/sys_time.h"
36 
37 #include <libopencm3/stm32/gpio.h>
38 #include <libopencm3/stm32/rcc.h>
39 #include <libopencm3/cm3/systick.h>
40 #include "std.h"
41 
47 static inline uint32_t get_sys_time_usec(void)
48 {
49  return sys_time.nb_sec * 1000000 +
51  usec_of_cpu_ticks(systick_get_reload() - systick_get_value());
52 }
53 
58 static inline uint32_t get_sys_time_msec(void)
59 {
60  return sys_time.nb_sec * 1000 +
62  msec_of_cpu_ticks(systick_get_reload() - systick_get_value());
63 }
64 
65 
71 static inline void sys_time_usleep(uint32_t us)
72 {
73  // start time
74  uint32_t start = systick_get_value();
75  // max time of one full counter cycle (n + 1 ticks)
76  uint32_t DT = usec_of_cpu_ticks(systick_get_reload() + 1);
77  // number of cycles
78  uint32_t n = us / DT;
79  // remaining number of cpu ticks
80  uint32_t rem = cpu_ticks_of_usec(us % DT);
81  // end time depend on the current value of the counter
82  uint32_t end;
83  if (rem < start) {
84  end = start - rem;
85  } else {
86  // one more count flag is required
87  n++;
88  end = systick_get_reload() - rem + start;
89  }
90  // count number of cycles (when counter reachs 0)
91  while (n) {
92  while (!systick_get_countflag());
93  n--;
94  }
95  // wait remaining ticks
96  while (systick_get_value() > end);
97 }
98 
99 #endif /* SYS_TIME_ARCH_H */
static uint32_t msec_of_cpu_ticks(uint32_t cpu_ticks)
Definition: sys_time.h:193
static uint32_t usec_of_cpu_ticks(uint32_t cpu_ticks)
Definition: sys_time.h:198
Architecture independent timing functions.
uint32_t get_sys_time_usec(void)
Get the time in microseconds since startup.
Definition: sys_time_arch.c:68
unsigned long uint32_t
Definition: types.h:18
volatile uint32_t nb_sec_rem
remainder of seconds since startup in CPU_TICKS
Definition: sys_time.h:73
void sys_time_usleep(uint32_t us)
sys_time_usleep(uint32_t us)
Definition: sys_time_arch.c:95
volatile uint32_t nb_sec
full seconds since startup
Definition: sys_time.h:72
uint32_t get_sys_time_msec(void)
Get the time in milliseconds since startup.
Definition: sys_time_arch.c:78
static uint32_t cpu_ticks_of_usec(uint32_t usec)
Definition: sys_time.h:178