arm_timer.cpp

00001 #include "mbed.h"
00002 #include "arm_hal_timer.h"
00003 
00004 static void (*sn_callback)(void) = NULL;
00005 static Ticker sn_timer;
00006 //static uint32_t sn_compare_value;
00007 static timestamp_t sn_compare_value;
00008 static bool timer_enabled = false;
00009  
00010 #define MAXIMUM_SLOTS 10000
00011  
00012 extern "C" void arm_timer_init(void)
00013 {
00014     //init in Ticker ctor
00015 }
00016  
00017 extern "C" void arm_timer_set_cb(void (*callback)(void))
00018 {
00019     sn_callback = callback;
00020 }
00021  
00022 extern "C" void arm_timer_start(uint16_t slots)
00023 {
00024     sn_compare_value = slots * 50; // 1 slot = 50us
00025     sn_timer.attach_us(sn_callback, sn_compare_value);
00026     timer_enabled = true;
00027 }
00028  
00029 extern "C" void arm_timer_stop(void)
00030 {
00031     sn_timer.detach();
00032     timer_enabled = false;
00033 }
00034  
00035 extern "C" uint16_t arm_timer_get_remaining_slots(void)
00036 {
00037     uint32_t counter = us_ticker_read();
00038     uint32_t slots = ((sn_compare_value - counter) / 50);
00039  
00040     if ((slots > MAXIMUM_SLOTS) || (timer_enabled == false)) {
00041         slots = 0;
00042     }
00043 
00044     return (uint16_t)slots;
00045 }