Interfacing COM.X SIM7020G NB-IOT module with Arduino/STM32

  • Greetings everyone,

    This is first time, I am using any simcom microcontroller and m5stack modules. I apologize if question is too dumb.

    I want to interface COM.X SIM7020G NB-IOT module with my arduino or STM32L0RB microcontroller.

    Here, I am little confused about connection between Rx Tx pins. I referred hardware design guidelines of SIM7020G and it is stated that UART is working on 1.8V. As you all know, Arduino Uno works on 5V logic and STM32 works on 3.3V logic. Due to this I need voltage logic level converter.

    But I have seen people to use SIm700,800,800C,7000 breakout board without logic level converter. I am confused that should I use voltage logic level converter or voltage divider for serial communication??

    Also, Is there any tutorial for beginners like me to know m5stack modules?

    Thank you so much in advance for help

  • Hello @jeetS

    the SIM7020G itself is 1.8 V, but there are level shifters (to 3.3 V) already installed on the green board holding the SIM7020G. So TX and RX available on the M5Stack Bus are 3.3 V.

    So, yes, for an Arduino running on 5 V you would need an additional level shifter. For an ESP32 or an STM32 which use 3.3 V a direct connection is fine.


  • @felmue Thank you so much Felix !

    Have a good day (: