global: add ms in us sleep utilities

global.c

@@ -15,23 +15,26 @@
 /** global definitions and methods (code)
  *  @file global.c
  *  @author King Kévin <kingkevin@cuvoodoo.info>
- *  @date 2016
+ *  @date 2016-2017
  */
 /* standard libraries */
 #include <stdint.h> // standard integer types
 #include <stdlib.h> // general utilities
 
 /* STM32 (including CM3) libraries */
+#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
+#include <libopencm3/cm3/nvic.h> // interrupt handler
+#include <libopencm3/cm3/systick.h> // SysTick library
 #include <libopencm3/stm32/rcc.h> // real-time control clock library
 #include <libopencm3/stm32/gpio.h> // general purpose input output library
 #include <libopencm3/stm32/timer.h> // timer library
-#include <libopencm3/cm3/nvic.h> // interrupt handler
 #include <libopencm3/stm32/exti.h> // external interrupt defines
 
 #include "global.h" // common methods
 #include "string.h" // memory utilities
 
 volatile bool button_flag = false;
+volatile uint32_t sleep_duration = 0; /**< sleep duration count down (in SysTick interrupts) */
 
 char* b2s(uint64_t binary, uint8_t rjust)
 {
@@ -79,6 +82,44 @@ void led_toggle(void)
 	gpio_toggle(GPIO(LED_PORT), GPIO(LED_PIN));
 }
 
+void sleep_us(uint32_t duration)
+{
+	systick_counter_disable(); // disable SysTick to reconfigure it
+	systick_clear(); // reset SysTick
+	systick_set_frequency(1000000,rcc_ahb_frequency); // set SysTick frequency to microseconds
+	systick_interrupt_enable(); // enable interrupt to count duration
+	sleep_duration = duration; // save sleep duration for count down
+	systick_counter_enable(); // start counting
+	while (sleep_duration) { // wait for count down to complete
+		__WFI(); // go to sleep	
+	}
+}
+
+void sleep_ms(uint32_t duration)
+{
+	systick_counter_disable(); // disable SysTick to reconfigure it
+	systick_clear(); // reset SysTick
+	systick_set_frequency(1000,rcc_ahb_frequency); // set SysTick frequency to milliseconds
+	systick_interrupt_enable(); // enable interrupt to count duration
+	sleep_duration = duration; // save sleep duration for count down
+	systick_counter_enable(); // start counting
+	while (sleep_duration) { // wait for count down to complete
+		__WFI(); // go to sleep	
+	}
+}
+
+/** SysTick interrupt handler */
+void sys_tick_handler(void)
+{
+	if (sleep_duration) {
+		sleep_duration--; // decrement duration
+	}
+	if (0==sleep_duration) { // sleep complete
+		systick_counter_disable(); // stop systick
+		systick_interrupt_disable(); // stop interrupting
+	}
+}
+
 void board_setup(void)
 {
 	// setup LED

global.h

@@ -362,6 +362,16 @@ void led_off(void);
 /** toggle board LED */
 void led_toggle(void);
 
+/** go to sleep for some microseconds
+ *  @param[in] duration sleep duration in us
+ */
+void sleep_us(uint32_t duration);
+
+/** go to sleep for some milliseconds
+ *  @param[in] duration sleep duration in ms
+ */
+void sleep_ms(uint32_t duration);
+
 /** setup board peripherals */
 void board_setup(void);