drivers/mq3: avoid use of floats

RIOT-OS · May 31, 2023 · 6275068 · 6275068
1 parent d742513
commit 6275068
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Showing 2 changed files with 11 additions and 10 deletions.
diff --git a/drivers/include/mq3.h b/drivers/include/mq3.h
@@ -50,8 +50,8 @@ typedef struct {
  * @param[out] dev      device descriptor of an MQ-3 sensor
  * @param[in] adc_line  the ADC device the sensor is connected to
  *
- * @return              0 on success
- * @return              -1 on error
+ * @retval  0       success
+ * @retval  -1      failure
  */
 int mq3_init(mq3_t *dev, adc_t adc_line);
 
@@ -62,7 +62,7 @@ int mq3_init(mq3_t *dev, adc_t adc_line);
  *
  * @return              the raw sensor value, between 0 and MQ3_MAX_RAW_VALUE
  */
-int mq3_read_raw(const mq3_t *dev);
+int16_t mq3_read_raw(const mq3_t *dev);
 
 /**
  * @brief   Read the scaled sensor value of PPM of alcohol
@@ -71,7 +71,7 @@ int mq3_read_raw(const mq3_t *dev);
  *
  * @return              the scaled sensor value in PPM of alcohol
  */
-int mq3_read(const mq3_t *dev);
+int16_t mq3_read(const mq3_t *dev);
 
 #ifdef __cplusplus
 }

diff --git a/drivers/mq3/mq3.c b/drivers/mq3/mq3.c
@@ -21,23 +21,24 @@
 #include "mq3.h"
 
 #define PRECISION           ADC_RES_10BIT
-#define MIN                 (100U)              /* TODO: calibrate to useful value */
-#define FACTOR              (2.33f)             /* TODO: calibrate to useful value */
+#define MIN                 (100)               /* TODO: calibrate to useful value */
+#define FACTOR              (233)               /* TODO: calibrate to useful value */
+#define DIVISOR             (100)
 
 int mq3_init(mq3_t *dev, adc_t adc_line)
 {
     dev->adc_line = adc_line;
     return adc_init(dev->adc_line);
 }
 
-int mq3_read_raw(const mq3_t *dev)
+int16_t mq3_read_raw(const mq3_t *dev)
 {
     return adc_sample(dev->adc_line, PRECISION);
 }
 
-int mq3_read(const mq3_t *dev)
+int16_t mq3_read(const mq3_t *dev)
 {
-    float res = mq3_read_raw(dev);
+    int32_t res = mq3_read_raw(dev);
     res = (res > MIN) ? res - MIN : 0;
-    return (int)(res * FACTOR);
+    return res * FACTOR / DIVISOR;
 }