SDAA112 September   2025 AM625

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Use Case
  5. 2Platform and Products
    1. 2.1 Hardware
    2. 2.2 Software
  6. 3Methods
  7. 4Overview of Steps to Bring Up the Interface and Establish A Connection
  8. 5Troubleshooting
    1. 5.1 Power and Initialization First
    2. 5.2 Verify Network Before PPP
    3. 5.3 Test Manual Dial First
    4. 5.4 Timing When Dialing Up
    5. 5.5 Serial Communication
    6. 5.6 Chat Script
    7. 5.7 PPP Options
    8. 5.8 Signal Strength and Antenna Setup
    9. 5.9 Modem Reset
  9. 6Summary
  10. 7References

2.1 Hardware

The required hardware is a processor, a cellular modem with either a UART or USB connection between them, and a means of console-based development.

This implementation was developed on the TI AM625 processor using the BeaglePlay single-board computer, together with a Quectel BG95 multimode LPWA cellular module. However, the steps discussed in this application note can be used with other TI ARM processors running Linux as the procedures and protocols are processor agnostic.

Connectivity between the processor and modem was achieved through the microBUS click header for UART communication, though USB is also supported in typical designs. Since UART is used here, this implementation is restricted to low bit rate applications. An active Hologram SIM card was inserted into the modem. Development and debugging were performed on a Linux host system connected to the BeaglePlay.

Necessary Hardware Figure 2-1 Necessary Hardware

The entire implementation can be done with the above connections to the BeaglePlay and cell modem. Once the BeaglePlay board is powered, the USB Type-C port serves dual purposes as both the primary power source and USB gadget, allowing for a development access point. Through this connection, the host PC can establish an SSH session (see Connect WiFi - step 2 ssh debian@192.168.8.1) with the board, creating a convenient environment for configuring the modem and initiating PPP connections without requiring additional interfaces.

Connection to the BG95 from the BeaglePlay is limited to UART when utilizing the mikroBUS click header, but many times USB is used between the processor and the modem.

The following additional setup is helpful for further debugging.

Additional Hardware Figure 2-2 Additional Hardware

The UART connection between the BeaglePlay and the host PC allows an interactive boot console and access to boot logs during startup. After a successful boot, the same logs can be accessed over an SSH session using the dmesg command. This connection is optional.

A USB-to-Micro-USB connection between the host PC and the BG95 provides direct access to the modem to verify functionality before attempting to communicate through the BeaglePlay. This connection is optional.