Thingy:91 - I2C pins voltage level

[Jacobk]

Hi,

We are using I2C to communicate with a sensor from the thingy:91. The sensor need either 3.3 V or 5 V I/O voltage levels to communicate.

As we understand it, the thingy is only capable to send out 1.8 V on the I/O pins. Is there any way to raise this without external circuits?

Thanks in advance!

regards

Jacob

[JONATHAN LL]

Hi Jacob,

There are three voltage domains for the Thingy91, VSYS, 1.8V and 3.3V, more info here. The 3.3V is for analog circuits like LEDs.

3.3V is accessible on P5 and TP19, here is the connector list: https://infocenter.nordicsemi.com/topic/ug_thingy91/UG/thingy91/hw_description/hw_connector_pinout.html?cp=13_0_6_12_1_0 



As for the nrf9160 the GPIO can go higher than 1.8V. https://infocenter.nordicsemi.com/topic/ps_nrf9160/pmu_regulators.html?cp=2_0_0_4_0_1_0#normal 


But as you can see from the block diagram the Thingy91 is only supplied 1.8V to  the GPIO, https://infocenter.nordicsemi.com/topic/ug_thingy91/UG/thingy91/hw_description/block_diagram.html?cp=13_0_6_0 


How do you connect to the sensor, what pin connectors are you using?

The P6 Connector is connected to the nrf52840 SoC.

Regards,
Jonathan

[Jacobk]

Hi, Jonathan

We are thinking about using the TP9 and TP10 pins for the I2C communication , but we are still unsure if these pins supply LVTTL 3.3 V for I2C.

Is possible to use these pins with 3.3 V or are there other pins on thingy:91 that we can use? (that are connected to the nrf9160)

regards,

Jacob

[JONATHAN LL]

Hi,

There is no option to configure the GPIO's to supply 3.3V on the Thingy91.

You can of course use som external level shifter or other circuitry between the two devices.

Regards,
Jonathan