Using Sim card and UART simultaneously on nRF9160dk

[Jagruti]

Hello,

On nordic nRF9160dk I want to send SMS and receive the data from UART simultaneously. UART needs 3V VDD supply and for Sim card it is 1.8V. So how this condition can be fulfilled at the same time? For now I am using 3V VDD GPIO supply and both are working. But for sim card it is better to use 1.8V, so what is the solution for this?

Thanks,

Jagruti

[Håkon Alseth]

Hi,

 

The SIM card is powered from the nRF9160, and it is supplied with a 1.8V source regardless of what the VDD_GPIO is set to.

The SIM_* pins are dedicated to SIM communication, and cannot be reconfigured for other purposes.

When you are sending and receiving any type of data over the network (SMS, IP, etc), this is not going through your SIM at all. The SIM is used to authenticate you on the network itself, and after that is done, you send data, like SMS or IP data, using the CPU in the microcontroller.

Sending or receiving data over IP or SMS is therefore not directly coupled with the UART, meaning that you should be able to do both (provided that the CPU is not busy).

 

Kind regards,

Håkon

[Jagruti]

Thank you so much for the information.

But I still have one doubt. In nRF9160dk_user_guide, there is one sentence "The voltage
can be selected to 1.8 V or 3 V using slide switch SW11. For optimal performance of the nRF9160
radio, it is recommended that only 1.8 V is used." So in my case is it okay set VDD_GPIO to 3V or 3.3V?

[Håkon Alseth]

Jagruti said:

For optimal performance of the nRF9160
radio, it is recommended that only 1.8 V is used." So in my case is it okay set VDD_GPIO to 3V or 3.3V?

 It is safe to use 3 or 3.3V on VDD_IO. This is a recommendation if you are to use high current and high speed switching (PWM, SPI) on GPIOs physically near the ANT pin, but the impact in a real-life application is minimal.

 

Kind regards,

Håkon