BMP280 driver: Forced mode. Soft reset.

examples/bmp280/bmp280_example.c

@@ -8,12 +8,46 @@
 
 #include "bmp280/bmp280.h"
 
+// In forced mode user initiate measurement each time.
+// In normal mode measurement is done continuously with specified standby time. 
+// #define MODE_FORCED
 
 const uint8_t scl_pin = 5;
 const uint8_t sda_pin = 4;
 
+#ifdef MODE_FORCED
+static void bmp280_task_forced(void *pvParameters)
+{
+    bmp280_params_t  params;
+    float pressure, temperature;
 
-static void bmp280_task(void *pvParameters)
+    bmp280_init_default_params(&params);
+    params.mode = BMP280_MODE_FORCED;
+
+    while (1) {
+        while (!bmp280_init(&params, scl_pin, sda_pin)) {
+            printf("BMP280 initialization failed\n");
+            vTaskDelay(1000 / portTICK_RATE_MS);
+        }
+
+        while(1) {
+            vTaskDelay(1000 / portTICK_RATE_MS);
+            if (!bmp280_force_measurement()) {
+                printf("Failed initiating measurement\n");
+                break;
+            }
+            while (bmp280_is_measuring()) {}; // wait for measurement to complete
+
+            if (!bmp280_read(&temperature, &pressure)) {
+                printf("Temperature/pressure reading failed\n");
+                break;
+            }
+            printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
+        }
+    }
+}
+#else
+static void bmp280_task_normal(void *pvParameters)
 {
     bmp280_params_t  params;
     float pressure, temperature;
@@ -35,6 +69,7 @@ static void bmp280_task(void *pvParameters)
         }
     }
 }
+#endif
 
 void user_init(void)
 {
@@ -45,5 +80,9 @@ void user_init(void)
     printf("SDK version : %s\n", sdk_system_get_sdk_version());
     printf("GIT version : %s\n", GITSHORTREV);
 
-    xTaskCreate(bmp280_task, (signed char *)"bmp280_task", 256, NULL, 2, NULL);
+#ifdef MODE_FORCED
+    xTaskCreate(bmp280_task_forced, (signed char *)"bmp280_task", 256, NULL, 2, NULL);
+#else
+    xTaskCreate(bmp280_task_normal, (signed char *)"bmp280_task", 256, NULL, 2, NULL);
+#endif
 }

extras/bmp280/bmp280.c

@@ -163,6 +163,10 @@ bool bmp280_init(bmp280_params_t *params, uint8_t scl_pin, uint8_t sda_pin)
     uint8_t oversampling_temp =
         (params->oversampling == BMP280_ULTRA_HIGH_RES) ? 2 : 1;
 
+    if (params->mode == BMP280_MODE_FORCED) {
+        params->mode = BMP280_MODE_SLEEP;  // initial mode for forced is sleep
+    }
+
     uint8_t ctrl = (oversampling_temp << 5) | (params->oversampling << 2)
         | (params->mode);
 
@@ -176,7 +180,25 @@ bool bmp280_init(bmp280_params_t *params, uint8_t scl_pin, uint8_t sda_pin)
 
 bool bmp280_force_measurement()
 {
-    // TODO: implement
+    uint8_t ctrl = read_register8(BMP280_REG_CTRL);
+    ctrl &= ~0b11;  // clear two lower bits
+    ctrl |= BMP280_MODE_FORCED;
+    debug("Writing ctrl reg=%x", ctrl);
+    if (!write_register8(BMP280_REG_CTRL, ctrl)) {
+        debug("Failed starting forced mode");
+        return false;
+    }
+    return true;
+}
+
+bool bmp280_is_measuring()
+{
+    uint8_t status = read_register8(BMP280_REG_STATUS);
+    if (status & (1<<3)) {
+        debug("Status: measuring");
+        return true;
+    }
+    debug("Status: idle");
     return false;
 }
 
@@ -255,3 +277,12 @@ bool bmp280_read(float *temperature, float *pressure)
 
     return true;
 }
+
+bool bmp280_soft_reset()
+{
+    if (!write_register8(BMP280_REG_RESET, BMP280_RESET_VALUE)) {
+        debug("Failed resetting sensor");
+        return false;
+    }
+    return true;
+}

extras/bmp280/bmp280.h

@@ -30,7 +30,7 @@
 /**
  * Uncomment to enable debug output.
  */
-#define BMP280_DEBUG
+// #define BMP280_DEBUG
 
 /**
  * BMP280 address is 0x77 if SDO pin is high,
@@ -44,6 +44,7 @@
  * Normal - Continues measurement.
  */
 typedef enum {
+    BMP280_MODE_SLEEP = 0,
     BMP280_MODE_FORCED = 1,
     BMP280_MODE_NORMAL = 3
 } BMP280_Mode;
@@ -95,7 +96,11 @@ typedef struct {
 
 /**
  * Initialize default parameters.
- * Default configuration is NORMAL mode.
+ * Default configuration:
+ *      mode: NORAML
+ *      filter: OFF
+ *      oversampling: x4
+ *      standby time: 250ms
  */
 void bmp280_init_default_params(bmp280_params_t *params);
 
@@ -111,9 +116,22 @@ bool bmp280_init(bmp280_params_t *params, uint8_t scl_pin, uint8_t sda_pin);
  */
 bool bmp280_force_measurement();
 
+/**
+ * Check if BMP280 is busy with measuring temperature/pressure.
+ * Return true if BMP280 is busy.
+ */
+bool bmp280_is_measuring();
+
 /**
  * Read compensated temperature and pressure data.
+ * Temperature in degrees Celsius.
+ * Pressure in Pascals.
  */
 bool bmp280_read(float *temperature, float *pressure);
 
+/**
+ * Restart BMP280 module.
+ */
+bool bmp280_soft_reset();
+
 #endif  // __BMP280_H__