The SIM card can't work，and the measurement IO(sim_1.8v) port has no output.

[Jerry zheng]

We customized our own development board based on Nordic's Thingy91 development board. Now it's welded, the circuit works, and we've flash demo MQTT_simple and Asset_cracker_v2, including some LTE related programs, but the SIM card doesn't work. The 1.8V output voltage of the chip was not detected, so we want to ask if there is any deficiency in the circuit design. Or what other software configuration is required? Please point the way.

Attached is our schematic diagram.

[Kazi Afroza Sultana]

Hello,

Could you please check if your sim supports 1.8 V or not? There are many SIMs which require higher voltage. The modem will turn on voltage on 1.8V to the SIM and try to communicate with the SIM. If the communication fails, the voltage will turn off. According to our power expat, what you are observing now is a communication failing. So, system is not able to talk to the sim and it does not mean that hardware connections are wrong.

Thanks.

Best Regards,

Kazi Afroza Sultana