XBee 3 LTE-M/NB-IoT AT Command and Firmware Update Issues with FT230XS-U and TPS560430X3FDBVR

XBee & XBee Gateway
1

Below is a detailed English explanation of the issue, summarizing the current situation, hardware setup, observed behavior, and specific problems with the Digi XBee 3 Global LTE-M/NB-IoT module, based on the provided information.

Detailed Issue Description

Overview

I am using a Digi XBee 3 Global LTE-M/NB-IoT module interfaced with a computer via a FT230XS-U USB-to-UART IC for communication. The XBee 3 is powered by a TPS560430X3FDBVR switching regulator, which converts the USB’s 5V supply to 3.3V. Using XCTU (Digi’s configuration software), I can establish communication with the XBee 3 and view its status (e.g., parameter settings such as firmware version, hardware version, and other configurations). However, two critical issues persist:

  1. AT commands requiring return values (e.g., ATVR, ATBD, AT+CSQ) do not respond, while AT commands without return values (e.g., AT, ATCN) correctly return OK.
  2. Firmware updates cannot be performed through XCTU, likely resulting in error messages such as “Connection Lost,” “Timeout,” or “Invalid Firmware.”

Hardware Setup

  • FT230XS-U USB-to-UART IC:
    • Provides UART communication between the computer and the XBee 3.
    • UART connections:
      • FT230XS-U TXD → XBee 3 DIN (Pin 3).
      • FT230XS-U RXD → XBee 3 DOUT (Pin 2).
      • Common GND between FT230XS-U and XBee 3.
    • Logic level: Assumed to be 3.3V (via VCCIO pin, likely connected to the 3.3V output of the regulator, but requires confirmation).
    • Hardware flow control (RTS/CTS): Status unknown (not confirmed if connected to XBee 3’s RTS Pin 16 and CTS Pin 12).
  • TPS560430X3FDBVR Switching Regulator:
    • Converts USB’s 5V to 3.3V to power the XBee 3’s VCC (Pin 1).
    • Specifications:
      • Fixed 3.3V output.
      • Maximum output current: 600mA.
2

You are not meeting the modules power requirements. The module in its default configuration will need up to 2A of current. See Digi XBee®3 Global LTE-M/NB-IoT User Guide (with Low Power)

I would suggest you obtain a Digi interface board to work from. It will help you in debugging your application by providing you a known good point in which to work from. the part number for this would be XBIB-CU-TH.