semaphore for SPI bus access removed from the driver, the user has to deal with concurrency

examples/bme680/bme680_one_sensor/bme680_one_sensor.c

@@ -138,10 +138,7 @@ void user_init(void)
 
     if (sensor)
     {
-        // Create a task that uses the sensor
+        /** -- SENSOR CONFIGURATION PART (optional) --- */
-        xTaskCreate(user_task, "user_task", TASK_STACK_DEPTH, NULL, 2, NULL);
-
-        /** -- OPTIONAL PART -- */
 
         // Changes the oversampling rates to 4x oversampling for temperature
         // and 2x oversampling for humidity. Pressure measurement is skipped.
@@ -156,5 +153,15 @@ void user_init(void)
 
         // Set ambient temperature to 10 degree Celsius
         bme680_set_ambient_temperature (sensor, 10);
+            
+        /** -- TASK CREATION PART --- */
+
+        // must be done last to avoid concurrency situations with the sensor 
+        // configuration part
+
+        // Create a task that uses the sensor
+        xTaskCreate(user_task, "user_task", TASK_STACK_DEPTH, NULL, 2, NULL);
     }
+    else
+        printf("Could not initialize BME680 sensor\n");
 }

extras/bme680/README.md

@@ -378,10 +378,7 @@ Optionally, you could wish to set some measurement parameters. For details see t
 ```
 if (sensor)
 {
-    // Create a task that uses the sensor
+    /** -- SENSOR CONFIGURATION PART (optional) --- */
-    xTaskCreate(user_task, "user_task", 256, NULL, 2, NULL);
-
-    /** -- OPTIONAL PART -- */
 
     // Changes the oversampling rates to 4x oversampling for temperature
     // and 2x oversampling for humidity. Pressure measurement is skipped.
@@ -394,11 +391,21 @@ if (sensor)
     bme680_set_heater_profile (sensor, 0, 200, 100);
     bme680_use_heater_profile (sensor, 0);
 
+    /** -- TASK CREATION PART --- */
+
+    // must be done last to avoid concurrency situations with the sensor 
+    // configuration part
+
+    // Create a task that uses the sensor
+    xTaskCreate(user_task, "user_task", TASK_STACK_DEPTH, NULL, 2, NULL);
+
     ...
 }
 ```
 
-Last, the user task that uses the sensor has to be created.
+Finally, a user task that uses the sensor has to be created.
+
+**Please note:** To avoid concurrency situations when driver functions are used to access the sensor, for example to read data, the user task must not be created until the sensor configuration is completed.
 
 
 ### User task
@@ -566,10 +573,7 @@ void user_init(void)
 
     if (sensor)
     {
-        // Create a task that uses the sensor
+        /** -- SENSOR CONFIGURATION PART (optional) --- */
-        xTaskCreate(user_task, "user_task", TASK_STACK_DEPTH, NULL, 2, NULL);
-
-        /** -- OPTIONAL PART -- */
 
         // Changes the oversampling rates to 4x oversampling for temperature
         // and 2x oversampling for humidity. Pressure measurement is skipped.
@@ -584,7 +588,17 @@ void user_init(void)
 
         // Set ambient temperature to 10 degree Celsius
         bme680_set_ambient_temperature (sensor, 10);
+            
+        /** -- TASK CREATION PART --- */
+
+        // must be done last to avoid concurrency situations with the sensor 
+        // configuration part
+
+        // Create a task that uses the sensor
+        xTaskCreate(user_task, "user_task", TASK_STACK_DEPTH, NULL, 2, NULL);
     }
+    else
+        printf("Could not initialize BME680 sensor\n");
 }
 ```
 

extras/bme680/bme680.c

@@ -305,8 +305,6 @@ bme680_sensor_t* bme680_init_sensor(uint8_t bus, uint8_t addr, uint8_t cs)
         free (dev);
         return NULL;
     }
-    if (!addr) 
-        spi_semaphore_init(dev);
 
     // reset the sensor
     if (!bme680_reset(dev))
@@ -1278,12 +1276,9 @@ static bool bme680_spi_read(bme680_sensor_t* dev, uint8_t reg, uint8_t *data, ui
         return false;
     }
 
-    spi_semaphore_take (dev);
-
     // set mem page first
     if (!bme680_spi_set_mem_page (dev, reg))
     {
-        spi_semaphore_give (dev);
         error_dev ("Error on read from SPI slave on bus 1. Could not set mem page.",
                    __FUNCTION__, dev);
         return false;
@@ -1302,7 +1297,6 @@ static bool bme680_spi_read(bme680_sensor_t* dev, uint8_t reg, uint8_t *data, ui
     
     if (!spi_transfer_pf (dev->bus, dev->cs, mosi, miso, len+1))
     {
-        spi_semaphore_give (dev);
         error_dev ("Could not read data from SPI", __FUNCTION__, dev);
         dev->error_code |= BME680_SPI_READ_FAILED;
         return false;
@@ -1311,8 +1305,6 @@ static bool bme680_spi_read(bme680_sensor_t* dev, uint8_t reg, uint8_t *data, ui
     for (int i=0; i < len; i++)
       data[i] = miso[i+1];
 
-    spi_semaphore_give (dev);
-    
     #ifdef BME680_DEBUG_LEVEL_2
     printf("BME680 %s: read the following bytes: ", __FUNCTION__);
     printf("%0x ", reg);
@@ -1340,15 +1332,11 @@ static bool bme680_spi_write(bme680_sensor_t* dev, uint8_t reg, uint8_t *data, u
         return false;
     }
 
-    if (reg != BME680_REG_STATUS)
-        spi_semaphore_take (dev);
-    
     // set mem page first if not mem page register is used
     if (reg != BME680_REG_STATUS && !bme680_spi_set_mem_page (dev, reg))
     {
         error_dev ("Error on write from SPI slave on bus 1. Could not set mem page.",
                    __FUNCTION__, dev);
-        spi_semaphore_give (dev);
         return false;
     }
 
@@ -1370,14 +1358,10 @@ static bool bme680_spi_write(bme680_sensor_t* dev, uint8_t reg, uint8_t *data, u
 
     if (!spi_transfer_pf (dev->bus, dev->cs, mosi, NULL, len+1))
     {
-        if (reg != BME680_REG_STATUS)
-            spi_semaphore_give (dev);
         error_dev ("Could not write data to SPI.", __FUNCTION__, dev);
         dev->error_code |= BME680_SPI_WRITE_FAILED;
         return false;
     }
-    if (reg != BME680_REG_STATUS)
-        spi_semaphore_give (dev);
 
     return true;
 }

extras/bme680/bme680_platform.h

@@ -66,12 +66,6 @@
 #include "esp/spi.h"
 #include "i2c/i2c.h"
 
-// platform specific definitions
-
-#define spi_semaphore_init(d)
-#define spi_semaphore_take(d)
-#define spi_semaphore_give(d)
-
 // platform specific SPI functions
 
 #define spi_bus_init(bus,sck,miso,mosi) // not needed on ESP8266