Digi XBee 3 User Manual

Operate in API mode API frame format
Digi XBee® 3 Cellular LTE Cat 1 AT&T Smart Modem User Guide
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Multi-byte values are sent big-endian.
Calculate and verify checksums
To calculate the checksum of an API frame:
1. Add all bytes of the packet, except the start delimiter 0x7E and the length (the second and
third bytes).
2. Keep only the lowest 8 bits from the result.
3. Subtract this quantity from 0xFF.
To verify the checksum of an API frame:
1. Add all bytes including the checksum; do not include the delimiter and length.
2. If the checksum is correct, the last two digits on the far right of the sum equal 0xFF.
Example
Consider the following sample data packet: 7E 00 0A 01 01 50 01 00 48 65 6C 6C 6F B8+
Byte(s) Description
7E Start delimiter
00 0A Length bytes
01 API identifier
01 API frame ID
50 01 Destination address low
00 Option byte
48 65 6C 6C 6F Data packet
B8 Checksum
To calculate the check sum you add all bytes of the packet, excluding the frame delimiter 7E and the
length (the second and third bytes):
7E 00 0A 01 01 50 01 00 48 65 6C 6C 6F B8
Add these hex bytes:
01 + 01 + 50 + 01 + 00 + 48 + 65 + 6C + 6C + 6F = 247
Now take the result of 0x247 and keep only the lowest 8 bits which in this example is 0xC4 (the two
far right digits). Subtract 0x47 from 0xFF and you get 0x3B (0xFF - 0xC4 = 0x3B). 0x3B is the checksum
for this data packet.
If an API data packet is composed with an incorrect checksum, the XBee Smart Modem will consider
the packet invalid and will ignore the data.
To verify the check sum of an API packet add all bytes including the checksum (do not include the
delimiter and length) and if correct, the last two far right digits of the sum will equal FF.
01 + 01 + 50 + 01 + 00 + 48 + 65 + 6C + 6C + 6F + B8 = 2FF

Digi XBee 3 Specifications

General

Model	XBee 3
Category	Modem
Frequency Bands	2.4 GHz, 868 MHz, 900 MHz
Interface	UART, SPI, I2C
Operating Temperature	-40° C to +85° C
Power Supply	2.1V to 3.6V
Antenna	External or onboard
Transmit Power	up to 20 dBm
Security	AES encryption
Protocols	Zigbee, 802.15.4, DigiMesh

Summary

Getting Started with the XBee Smart Modem

Connect Hardware and Install XCTU

Step-by-step instructions for connecting hardware and installing XCTU utility.

Update Firmware and Check Connection

Procedures for updating device firmware and verifying cellular connection status.

XBee Connection Examples

Getting Started with MicroPython

MicroPython Basics and Setup

Introduction to MicroPython and setting up the environment using XCTU.

MicroPython Examples

Update the Firmware

Plan for Firmware Updates

Update Device and Cellular Firmware

Procedures for updating device and cellular firmware using XCTU.

Update Telit Modem Firmware with XFP Utility

Instructions for updating the Telit modem firmware using the XFP utility.

AT Commands Reference

Special, Cellular, and Network Commands

Reference for special, cellular, and network configuration AT commands.

I/O, Sleep, and Mode Commands

Configuration commands for I/O settings, sleep modes, and operating modes.

File System, BLE, Socket, and API Commands

Commands for file system, BLE, sockets, and API frame management.

Troubleshooting Guide

Serial Port and Driver Issues

macOS Java Errors and Bypass Mode Issues

Network, SMS, and Baud Rate Troubleshooting