STSS22H No stretch one-shot timing

[allard]

I want to readout the STSS22H, without any polling or I2C clock stretching. I want to use the following sequence:

• Send soft reset command
• Send one shot command
• Release I2C bus for other processes to use
• Wait for the maximum conversion time of the one-shot mode
• Get the result
• Release I2C bus for other processes to use
• Wait for a couple seconds
• Repeat from step 1

Is this possible with the STSS22H, where can I find the maximum conversion time in one **** mode? This information is missing in the datasheet.

[Nandan V]

Does this help?

 

[allard]

No, it's a bit vague, does it mean that the sampling takes around 1000ms, seems a bit long.

[DSull.3 · Accepted solution]

Hi, the conversion time should depend from the ODR you set: the limit is 1Hz, so a complete conversion will take 1s. For higher ODRs, the conversion time will be lower (for example for ODR=25Hz the conversion time will be 1/25s = 40ms).

\DK

[allard]

Ok, then I will go with freerunning mode at a high ODR. Can I just sample the data registers without checking for the data ready flag (I just need a most recent sample, no sync of any kind needed), or will this cause I2C clock stretching?

I've got this running in a freeRTOS thread, but sometimes the BUSY bit of the I2C peripheral (STM32F4) gets stuck, i'm suspecting due to clock stretching.