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drivers/sensor: sht3xd: implement single shot mode

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For now there is only periodic data acquisition mode implemented.
This mode is quite power consuming. Based on datasheet in idle
state in periodic data acquisition mode SHT3X consumes 45uA but
in single shot mode 0.2uA. For many applications where power
consumption has to be kept as low as possible single shot mode
is the only choice. Tester on custom board NRF52832 + SHT31-DIS.

Signed-off-by: Michał Oleszczyk <oleszczyk.m@gmail.com>
This commit is contained in:
Michał Oleszczyk 2019-09-14 13:20:36 +02:00 • committed by Maureen Helm
commit da4d00ee0a
2 changed files with 42 additions and 1 deletions
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16
drivers/sensor/sht3xd/Kconfig
View file

@ -70,6 +70,20 @@ config SHT3XD_REPEATABILITY_HIGH
endchoice
choice
prompt "Measurement mode"
default SHT3XD_PERIODIC_MODE
config SHT3XD_SINGLE_SHOT_MODE
bool "single shot"
config SHT3XD_PERIODIC_MODE
bool "periodic data acquisition"
endchoice
if SHT3XD_PERIODIC_MODE
choice
prompt "Measurements per second"
default SHT3XD_MPS_1
@ -93,4 +107,6 @@ config SHT3XD_MPS_10
endchoice
endif # SHT3XD_PERIODIC_MODE
endif # SHT3XD

27
drivers/sensor/sht3xd/sht3xd.c
View file

@ -16,6 +16,12 @@
#define LOG_LEVEL CONFIG_SENSOR_LOG_LEVEL
LOG_MODULE_REGISTER(SHT3XD);
#ifdef CONFIG_SHT3XD_SINGLE_SHOT_MODE
static const u16_t measure_cmd[3] = {
0x2400, 0x240B, 0x2416
};
#endif
#ifdef CONFIG_SHT3XD_PERIODIC_MODE
static const u16_t measure_cmd[5][3] = {
{ 0x202F, 0x2024, 0x2032 },
{ 0x212D, 0x2126, 0x2130 },
@ -23,6 +29,7 @@ static const u16_t measure_cmd[5][3] = {
{ 0x2329, 0x2322, 0x2334 },
{ 0x272A, 0x2721, 0x2737 }
};
#endif
static const int measure_wait[3] = {
4000, 6000, 15000
@ -85,6 +92,22 @@ static int sht3xd_sample_fetch(struct device *dev, enum sensor_channel chan)
__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
#ifdef CONFIG_SHT3XD_SINGLE_SHOT_MODE
/* start single shot measurement */
if (sht3xd_write_command(dev,
measure_cmd[SHT3XD_REPEATABILITY_IDX])
< 0) {
LOG_DBG("Failed to set single shot measurement mode!");
return -EIO;
}
k_sleep(K_MSEC(measure_wait[SHT3XD_REPEATABILITY_IDX] / USEC_PER_MSEC));
if (i2c_read(i2c, rx_buf, sizeof(rx_buf), address) < 0) {
LOG_DBG("Failed to read data sample!");
return -EIO;
}
#endif
#ifdef CONFIG_SHT3XD_PERIODIC_MODE
u8_t tx_buf[2] = {
SHT3XD_CMD_FETCH >> 8,
SHT3XD_CMD_FETCH & 0xFF
@ -95,6 +118,7 @@ static int sht3xd_sample_fetch(struct device *dev, enum sensor_channel chan)
LOG_DBG("Failed to read data sample!");
return -EIO;
}
#endif
t_sample = (rx_buf[0] << 8) | rx_buf[1];
if (sht3xd_compute_crc(t_sample) != rx_buf[2]) {
@ -179,6 +203,7 @@ static int sht3xd_init(struct device *dev)
k_busy_wait(SHT3XD_CLEAR_STATUS_WAIT_USEC);
#ifdef CONFIG_SHT3XD_PERIODIC_MODE
/* set periodic measurement mode */
if (sht3xd_write_command(dev,
measure_cmd[SHT3XD_MPS_IDX][SHT3XD_REPEATABILITY_IDX])
@ -188,7 +213,7 @@ static int sht3xd_init(struct device *dev)
}
k_busy_wait(measure_wait[SHT3XD_REPEATABILITY_IDX]);
#endif
#ifdef CONFIG_SHT3XD_TRIGGER
if (sht3xd_init_interrupt(dev) < 0) {
LOG_DBG("Failed to initialize interrupt");