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1. STM32WB - BLE AT Server Overview
This application note describes the set of AT commands to control the STM32WB Series. AT commands are instructions used to control a modem. AT is the abbreviation of ATtention. For this concept, the Cortex®-M4 application microcontroller contains an AT project able to manage the concepts of GAP, GATT, Security and low-power. This document explains how to interface with the STM32WB Series microcontroller to manage multi BLE apps handling (such as AT P2P server, AT Heart Rate) and GAP/GATT custom applications using AT instructions.
The BLE_AT_Server application is available by downloading STM32CubeWB[1] release
This project implements a set of AT commands used to build GAP/GATT custom server or client, peripheral or central application. It also implements P2P Server or Heart Rate applications that could be directly selected. The objective is to have an intermediate abstraction layer in order to allow a user to develop a basic application with a limited sets of commands to send.
The following sections contain the interface description, the AT commands definition, and the description of some use cases.
1.1. AT commands
The AT instruction set is a standard developed by Hayes to control modems. The command set consists in a series of short text strings for performing operations: • at GAP level such as advertising, discovery, connection, security. • at GATT level such as services and characteristics management and discovery, and operation on characteristics.
The AT instructions are transfered through Cortex®-M4 application microcontroller low-power UART (LPUART) without flow control. The STM32WB Series microcontroller can be controlled either through a terminal emulator such as Tera Term or Termite, or through an embedded microcontroller AT client module.
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The terminal emulator must be configured with the following parameters:
• Baud rate: 9600 • Data: 8 bits • Parity: none • Stop: 1 bit • Flow control: none • Each frame is delimited by a \n character
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AT command is composed of SET and QUERY operations. A single operation can be executed at a time.
The format of these operations is defined as follow: • Set operation (a,b input parameters) • AT+CMD=a,b • OK • Query operation (a,b return parameters) • AT+CMD? • +CMD:a,b • OK
An event can be sent asynchronously by the server with following format:
• Events (a,b event parameters) • <EVT=a,b
1.2. General commands
List of commands: initialization commands
| Initialization commands |
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1.3. Initialization - reset - BLE_RST
SET: 1
QUERY: No query for this command, it will return an error.
Example: AT+BLE_RST=1 OK
Fast FUOTA for P2P server application