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SHT3x driver - small changes

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- crc8 lookup table is now static to be held in flash memory
- special handling for the timer overflow in sht3x_is_measuring removed
- initialization reduced to availability check
This commit is contained in:
Gunar Schorcht 2017-10-13 13:39:40 +02:00
parent 6d0545837c
commit 612dd391c1
1 changed files with 5 additions and 29 deletions
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34
extras/sht3x/sht3x.c
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@ -86,6 +86,7 @@ int32_t SHT3x_MEASURE_DURATION[3] = {30,20,20}; // [High, Medium, Low]
static bool sht3x_send_command (sht3x_sensor_t*, uint16_t);
static bool sht3x_read_data (sht3x_sensor_t*, uint8_t*, uint32_t);
static bool sht3x_get_status (sht3x_sensor_t*, uint16_t*);
// static bool sht3x_reset (sht3x_sensor_t*);
static uint8_t crc8 (uint8_t data[], int len);
@ -116,27 +117,10 @@ sht3x_sensor_t* sht3x_init_sensor(uint8_t bus, uint8_t addr)
uint16_t status;
// soft-reset including status check leads to i2c problems.
// if (!sht3x_reset (dev))
if (!sht3x_get_status (dev, & status))
{
error_dev ("could not reset or check the status of the sensor", __FUNCTION__, dev);
free(dev);
return NULL;
}
// clear sensor status register
if (!sht3x_send_command(dev, SHT3x_CLEAR_STATUS_CMD))
{
error_dev ("could not clear sensor status", __FUNCTION__, dev);
free(dev);
return NULL;
}
// check the again the status after clear status command
if (!sht3x_get_status(dev, &status))
{
error_dev ("could not get sensor status", __FUNCTION__, dev);
error_dev ("could not get sensor status", __FUNCTION__, dev);
free(dev);
return NULL;
}
@ -195,16 +179,9 @@ int32_t sht3x_is_measuring (sht3x_sensor_t* dev)
if (!dev->meas_first)
return 0;
uint32_t start_time = dev->meas_start_time ; // in us
uint32_t system_time = sdk_system_get_time(); // in us
uint32_t elapsed_time;
uint32_t elapsed_time;
if (system_time < start_time)
// in case of timer overflow
elapsed_time = (UINT32_MAX - start_time + system_time) / 1000; // in ms
else
// normal case
elapsed_time = (system_time - start_time) / 1000; // in ms
elapsed_time = (sdk_system_get_time() - dev->meas_start_time) / 1000; // in ms
if (elapsed_time >= SHT3x_MEASURE_DURATION[dev->repeatability])
return 0;
@ -395,7 +372,7 @@ static bool sht3x_get_status (sht3x_sensor_t* dev, uint16_t* status)
static uint8_t* crc8_table; // lookup table with precomputed crc values
static uint8_t crc8_table[256]; // lookup table with precomputed crc values
static bool crc8_first_time = true; // indicator whether table has still to be created
static void generate_crc8_table()
@ -422,7 +399,6 @@ static uint8_t crc8 (uint8_t data[], int len)
if (crc8_first_time)
{
crc8_first_time = false;
crc8_table = malloc(256);
generate_crc8_table ();
}