Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

drivers/mq3: avoid use of floats #19696

Merged
merged 1 commit into from
Jun 2, 2023
Merged

drivers/mq3: avoid use of floats #19696

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 4 additions & 4 deletions drivers/include/mq3.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand All @@ -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
Expand All @@ -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
}
Expand Down
17 changes: 11 additions & 6 deletions drivers/mq3/mq3.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -19,25 +19,30 @@
*/

#include "mq3.h"
#include "macros/math.h"

#define PRECISION ADC_RES_10BIT
#define MIN (100U) /* TODO: calibrate to useful value */
#define FACTOR (2.33f) /* TODO: calibrate to useful value */
/* TODO: calibrate to useful value */
#define MIN (100U)
/* TODO: calibrate to useful value */
#define SHIFT (12U)
#define FACTOR DIV_ROUND(233UL << SHIFT, 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);
uint32_t res = mq3_read_raw(dev);
res = (res > MIN) ? res - MIN : 0;
return (int)(res * FACTOR);
/* same as `(int16_t)(res * 2.33)` */
return (res * FACTOR) >> SHIFT;
}