Question:
We have to use multiple sensors on multiple I2C busses in the intended application.
As documented in the user manual for the sensor, the register MOD1 (0x11) contains the field IICadr in bits 6:5 as a read/write-value.
Would it be possible to only use A0 sensors and assign new I2C adresses dynamically in the initialization phase? For example: Power on sensor 1, readress to A1, power on sensor 2, readress to A2, etc.? Or is the only way to use multiple sensors on one specific I2C bus to use the preconfigured devices with different I2C adresses set from the factory?
We did already some tests, but were not successful. If a sensor is unpowered on the I2C bus it already has problematic effects on the bus-signal. So I assume despite the IICadr being writeable, it is not intended to be used in this way.
Could you please confirm or disprove my theory?
Solution:
The procedure to sequentially power on the TLI493D-W2BW/A2B6 (TLE493D-W2B6/P2B6/A2B6, TLV493D-A2BW) sensors to reconfigure the I2C address works exactly as you have described. Attached is a small manual BusModeWithMultipleA0Devices.pdf showing the concept (it is a different sensor type, but the same principle).
The powered off sensor should not influence the I2C communication, with one exception: Please actively pull the not used sensor to GND (via push/pull stage or e.g. 10 kOhm resistor) as an open VDD pin in rare cases can cause issues at the SCL/SDA line. See also the chapter VDD loss in the user manual.
