9

Operating modes

There are three different operating modes: freerun, one-shot and low ODR.

One-shot mode: (default) The measurement chain is switched on when the ONE_SHOT bit (bit 0 of the CTRL

register) is set to '1'. When the temperature measurement is completed, the device is put in power-down

condition. One-shot mode is available for measuring trigger frequencies up to 1 Hz.

Freerun mode: The measurement chain is always on. The results of temperature data measurements are

updated in the output registers at each conversion. Output registers are refreshed @ODR (25 Hz, 50 Hz, 100 Hz

and 200 Hz). This operating mode is active when the FREERUN bit of the CTRL register is set to logic value ‘1’.

Low-ODR mode: Temperature data are measured @ ODR = 1 Hz. This operating mode is active when the

LOW_ODR_START bit of the CTRL register is set to logic value ‘1’.

Before changing the operating mode or ODR frequency, the user has to power down the device by writing '0' to

both the FREERUN and LOW_ODR_START bits.

FREERUN LOW_ODR_START

Operating mode

1

0

Freerun mode:

- Chain is always ON

- Measuremenats are available @ ODR = 25 Hz, 50 Hz, 100 Hz, 200 Hz

0

0

One-shot mode (default):

- User must ask for a conversion using the ONE_SHOT bit, then the measurement chain is

shut down once the conversion ends.

0

1

Low-ODR mode:

- Data are available @ ODR = 1 Hz

9.1

Enable sequence for one-shot mode

The following sequence must be used for each acquisition in one-shot mode:

1.

Write 02h to register 0Ch [software reset]

2.

Write 00h to register 0Ch [software reset]

3.

Set the ONE_SHOT bit in the CTRL (04h) register [send one-shot command]

Note: After device power-on, wait at least 12 ms before accessing the register interface.

command

Conversion

Readout

Conversion

Readout

Device in

power-down

Device in

power-down

Device in

power-down

Soft

Reset

Soft

Reset

Reset procedure is required before each

one-shot command

One-shot

command

One-shot

STTS22H

Operating modes

DS12606 - Rev 4

page 18/29