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drivers/dht: simplified interface

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This commit is contained in:
Hauke Petersen 2016-01-21 18:42:36 +01:00
parent 044cb3c2f9
commit 6fca96c668
2 changed files with 26 additions and 68 deletions
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56
drivers/dht/dht.c
View File

@ -34,7 +34,7 @@
#include "dht.h"
#include "dht_params.h"
#define ENABLE_DEBUG (1)
#define ENABLE_DEBUG (0)
#include "debug.h"
#define PULSE_WIDTH_THRESHOLD (40U)
@ -91,10 +91,10 @@ int dht_init(dht_t *dev, const dht_params_t *params)
return 0;
}
int dht_read_raw(dht_t *dev, dht_data_t *data)
int dht_read(dht_t *dev, int16_t *temp, int16_t *hum)
{
uint8_t csum, sum;
uint16_t hum, temp;
uint16_t raw_hum, raw_temp;
/* send init signal to device */
gpio_clear(dev->pin);
@ -114,8 +114,8 @@ int dht_read_raw(dht_t *dev, dht_data_t *data)
*/
/* read the humidity, temperature, and checksum bits */
hum = read(dev->pin, 16);
temp = read(dev->pin, 16);
raw_hum = read(dev->pin, 16);
raw_temp = read(dev->pin, 16);
csum = (uint8_t)read(dev->pin, 8);
/* set pin high again - so we can trigger the next reading by pulling it low
@ -123,54 +123,32 @@ int dht_read_raw(dht_t *dev, dht_data_t *data)
gpio_init(dev->pin, GPIO_DIR_OUT, dev->pull);
gpio_set(dev->pin);
/* parse the RAW values */
DEBUG("RAW: temp: %7i hum: %7i\n", (int)temp, (int)hum);
data->humidity = hum;
data->temperature = temp;
/* and finally validate the checksum */
sum = (temp >> 8) + (temp & 0xff) + (hum >> 8) + (hum & 0xff);
/* validate the checksum */
sum = (raw_temp >> 8) + (raw_temp & 0xff) + (raw_hum >> 8) + (raw_hum & 0xff);
if ((sum != csum) || (csum == 0)) {
DEBUG("error: checksum invalid\n");
return -1;
}
return 0;
}
void dht_parse(dht_t *dev, dht_data_t *data, float *outrelhum, float *outtemp)
{
/* parse the RAW values */
DEBUG("RAW values: temp: %7i hum: %7i\n", (int)raw_temp, (int)raw_hum);
switch (dev->type) {
case DHT11:
*outrelhum = data->humidity >> 8;
*outtemp = data->temperature >> 8;
*temp = (int16_t)((raw_temp >> 8) * 10);
*hum = (int16_t)((raw_hum >> 8) * 10);
break;
case DHT22:
*outrelhum = data->humidity / 10;
/* the highest bit indicates a negative value */
if (data->temperature & 0x8000) {
*outtemp = (data->temperature & 0x7FFF) / -10;
*hum = (int16_t)raw_hum;
/* if the high-bit is set, the value is negative */
if (raw_temp & 0x8000) {
*temp = (int16_t)((raw_temp & ~0x8000) * -1);
}
else {
*outtemp = data->temperature / 10;
*temp = (int16_t)raw_temp;
}
break;
default:
DEBUG("unknown DHT type\n");
}
}
int dht_read(dht_t *dev, float *outrelhum, float *outtemp)
{
/* read data, fail on error */
dht_data_t data;
if (dht_read_raw(dev, &data) == -1) {
return -1;
return -2;
}
dht_parse(dev, &data, outrelhum, outtemp);
return 0;
}

38
drivers/include/dht.h
View File

@ -84,41 +84,21 @@ void dht_auto_init(void);
*/
int dht_init(dht_t *dev, const dht_params_t *params);
/**
* @brief read sensor data from device
/**
* @brief get a new temperature and humidity value from the device
*
* @note if reading fails or checksum is invalid, no new values will be
* written into the result values
*
* @param[in] dev device descriptor of a DHT device
* @param[out] relhum pointer to relative humidity in g/m^3
* @param[out] temp pointer to temperature in degrees Celsius
*
* @return 0 on success
* @return -1 on error
*/
int dht_read(dht_t *dev, float *relhum, float *temp);
/**
* @brief read sensor data from device
*
* @note When reading fails and the function indicates an error,
* data will contain garbage.
*
* @param[in] dev device descriptor of a DHT device
* @param[in] data pointer to DHT data object
* @param[out] temp temperature value [in °C * 10^-1]
* @param[out] hum relative humidity value [in percent * 10^-1]
*
* @return 0 on success
* @return -1 on checksum error
* @return -2 on parsing error
*/
int dht_read_raw(dht_t *dev, dht_data_t *data);
/**
* @brief parse raw sensor data into relative humidity and Celsius
*
* @param[in] dev device descriptor of a DHT device
* @param[in] data sensor data
* @param[out] relhum pointer to relative humidity in g/m^3
* @param[out] temp pointer to temperature in degrees Celsius
*/
void dht_parse(dht_t *dev, dht_data_t *data, float *relhum, float *temp);
int dht_read(dht_t *dev, int16_t *temp, int16_t *hum);
#ifdef __cplusplus
}