#32 Setting the US trigger pulse offset and duration inside the 01bsp…

…_us_ranging.c file

projects/01bsp_us_ranging/01bsp_us_ranging.c

@@ -4,6 +4,7 @@
  *
  * @brief This is a short example of how to do Ultrasound ranging with HC-SR04 sensor on the DotBot board.
  * This code currently works on nRF52840. To use the code on DotBot you need to define different GPIO for US sensor ON and READ pin (trigger and echo) in hc_sr04.c
+ * The result of the US ranging is passed in the us_callback as the us_reading parameter
  *
  * @copyright Inria, 2022
  *
@@ -16,7 +17,11 @@
 #include "hc_sr04.h"
 
 
-//=========================== defines =========================================
+//=========================== defines ===========================================
+
+// Defines for setting up the trigger pulse width and frequency
+#define PULSE_DURATION_MS       0.01
+#define PULSE_OFFSET_MS         200
 
 //=========================== prototypes =========================================
 
@@ -25,41 +30,42 @@ void timer_callback(void);                 // callback for timer0 after pulse_of
 
 //=========================== variables =========================================
 
+typedef struct {
+    NRF_TIMER_Type    *timer0;       // Pointer to the TIMER structure used for triggering US sensor
+    NRF_TIMER_Type    *timer1;       // Pointer to the TIMER structure used for reading the range on the US sensor
+} app_vars_t;
 
-NRF_TIMER_Type *timer0;                   // variable for passing the Timer for sensor trigger 
-NRF_TIMER_Type *timer1;                   // variable for passing the Timer for sensor echo measurement
-
+static app_vars_t app_vars;
 
 //=========================== main =========================================
 
 /**
  *  @brief The program starts executing here.
  */
 int main(void) {
-
-    timer0 = NRF_TIMER0;
-    timer1 = NRF_TIMER1;
+    app_vars.timer0 = NRF_TIMER0;
+    app_vars.timer1 = NRF_TIMER1;
 
     // uncomment if using this code on DotBot Turn ON the DotBot board regulator
-    //db_board_init();
+    db_board_init();
 
     // initilize the US sensor, set callback and chose the timers
-    hc_sr04_init(&us_callback, &timer_callback, timer0, timer1);
-   
-    // start ranging
-    hc_sr04_start();
+    hc_sr04_init(&us_callback, &timer_callback, app_vars.timer0, app_vars.timer1);
+
+    // initial timer settings for the trigger pulse - we can call this function if we want to change the parameters of the pulse
+    hc_sr04_on_set_trigger(PULSE_DURATION_MS, PULSE_OFFSET_MS);
 
     // start high frequency clock needed for PPI
     hfclk_init();
+
+    // start ranging
+    hc_sr04_start();
 
-    while (1) {
-
+    while (1) {        
         __WFE();      
         __SEV();
         __WFE();
-
     }
-
     // one last instruction, doesn't do anything, it's just to have a place to put a breakpoint.
     __NOP();
 }
@@ -69,9 +75,7 @@ int main(void) {
  *         The code ends up here every time a new measurement is taken. The new measurement is stored in us_reading argument
  */
 void us_callback(uint32_t us_reading) {
-
     __NOP();
-
 }
 
 /**
@@ -80,9 +84,7 @@ void us_callback(uint32_t us_reading) {
  *         We could change the pulse_offset_ms here by writting a new value to timer0->CC[0] and timer0->CC[1]
  */
 void timer_callback(void) {
-
     __NOP();
-
 }