Azure IoT Hub / Central lite client library for ESP32, using MQTT. It's written in C++, and meant to be as lighter library if compared to esp-azure library. It currently needs Arduino framework.
You can still use ESP-IDF framework, as long as you include arduino-esp32 as ESP-IDF component.
I'm trying to make the library works for another platform, like K210 with Maixduino framework. Code optimization and seperation are already prepared. Need more testing.
This is simple sample code to connect to Azure IoT Central and publish some telemetry and property.
#include <Arduino.h>
#include "AzureIoTLiteClient.h"
#include <WiFiClientSecure.h>
const char* ssidName = "<CHANGE_THIS>"; // your network SSID (name of wifi network)
const char* ssidPass = "<CHANGE_THIS>"; // your network password
AzureIoTConfig_t iotconfig {
"<CHANGE_THIS>", // Azure IoT Central - scopeId
"<CHANGE_THIS>", // deviceId
"<CHANGE_THIS>", // deviceKey
AZURE_IOTC_CONNECT_SYMM_KEY // Connection method
};
WiFiClientSecure wifiClient;
AzureIoTLiteClient iotclient(wifiClient);
bool isConnected = false;
static bool connectWiFi() {
Serial.printf("Connecting WIFI to SSID: %s\r\n", ssidName);
WiFi.begin(ssidName, ssidPass);
// Attempt to connect to Wifi network:
while (WiFi.status() != WL_CONNECTED) {
Serial.print(".");
// wait 1 second for re-trying
delay(1000);
}
Serial.printf("Connected to %s\r\n", ssidName);
Serial.print("IP: "); Serial.println(WiFi.localIP());
return true;
}
void onAzureIoTEvent(const AzureIoTCallbacks_e cbType, const AzureIoTCallbackInfo_t *callbackInfo) {
// ConnectionStatus
if (strcmp(callbackInfo->eventName, "ConnectionStatus") == 0) {
LOG_VERBOSE("Is connected ? %s (%d)", callbackInfo->statusCode == AzureIoTConnectionOK ? "YES" : "NO", callbackInfo->statusCode);
isConnected = callbackInfo->statusCode == AzureIoTConnectionOK;
return;
}
// payload buffer doesn't have a null ending.
// add null ending in another buffer before print
AzureIOT::StringBuffer buffer;
if (callbackInfo->payloadLength > 0) {
buffer.initialize(callbackInfo->payload, callbackInfo->payloadLength);
}
LOG_VERBOSE("[%s] event was received. Payload => %s\n", callbackInfo->eventName, buffer.getLength() ? *buffer : "EMPTY");
if (strcmp(callbackInfo->eventName, "Command") == 0) {
LOG_VERBOSE("Command name was => %s\r\n", callbackInfo->tag);
}
}
void setup() {
Serial.begin(115200);
if (!connectWiFi()) {
while(1)
;
// No point to continue
}
// Add callbacks
iotclient.setCallback(AzureIoTCallbackMessageSent, onAzureIoTEvent);
iotclient.setCallback(AzureIoTCallbackCommand, onAzureIoTEvent);
iotclient.setCallback(AzureIoTCallbackSettingsUpdated, onAzureIoTEvent);
// Must call this
iotclient.begin(&iotconfig);
// Do connect
iotclient.connect();
}
unsigned long lastTick = 0;
void loop() {
if (!iotclient.run()) {
return; //No point to continue
}
unsigned long now = millis();
// Send telemetry every 10 seconds
if (ms - lastTick > 10000) {
char msg[64] = {0};
int pos = 0;
bool errorCode = 0;
lastTick = now;
// Send telemetry, randomized for now
long tempVal = random(35, 40);
pos = snprintf(msg, sizeof(msg) - 1, "{\"temperature\": %.2f}", tempVal*1.0f);
msg[pos] = 0;
errorCode = iotclient.sendTelemetry(msg, pos);
// Send property
pos = snprintf(msg, sizeof(msg) - 1, "{\"temperatureAlert\": %d}", (tempVal >= 38));
msg[pos] = 0;
errorCode = iotclient.sendProperty(msg, pos);
if (!errorCode) {
LOG_ERROR("Sending message has failed with error code %d", errorCode);
}
}
}This sample is to connect with Azure IoT Hub. Notice that I use connection string, instead of SYM KEY. This example is targetted for ESP-WROVER-KIT board.
#include <Arduino.h>
#include "AzureIoTLiteClient.h"
#include <WiFiClientSecure.h>
const char* ssidName = "<CHANGE_THIS>"; // your network SSID (name of wifi network)
const char* ssidPass = "<CHANGE_THIS>"; // your network password
//Conn String format example: HostName=[BLA_BLA];DeviceId=[BLA_BLA];SharedAccessKey=[BLA_BLA]
AzureIoTConfig_t iotconfig("<CHANGE_THIS>");
WiFiClientSecure wifiClient;
AzureIoTLiteClient iotclient(wifiClient);
bool isConnected = false;
static bool connectWiFi() {
Serial.printf("Connecting WIFI to SSID: %s\r\n", ssidName);
WiFi.begin(ssidName, ssidPass);
// Attempt to connect to Wifi network:
while (WiFi.status() != WL_CONNECTED) {
Serial.print(".");
// wait 1 second for re-trying
delay(1000);
}
Serial.printf("Connected to %s\r\n", ssidName);
Serial.print("IP: "); Serial.println(WiFi.localIP());
return true;
}
void executeCommand(const char *cmdName, char *payload) {
if (strcmp(cmdName, "setLED") == 0) {
LOG_VERBOSE("Executing setLED -> value: %s", payload);
int ledVal = atoi(payload);
digitalWrite(2, ledVal);
}
}
void onEvent(const AzureIoTCallbacks_e cbType, const AzureIoTCallbackInfo_t *callbackInfo) {
// ConnectionStatus
if (strcmp(callbackInfo->eventName, "ConnectionStatus") == 0) {
LOG_VERBOSE("Is connected ? %s (%d)", callbackInfo->statusCode == AzureIoTConnectionOK ? "YES" : "NO", callbackInfo->statusCode);
isConnected = callbackInfo->statusCode == AzureIoTConnectionOK;
return;
}
// payload buffer doesn't have a null ending.
// add null ending in another buffer before print
AzureIOT::StringBuffer buffer;
if (callbackInfo->payloadLength > 0) {
buffer.initialize(callbackInfo->payload, callbackInfo->payloadLength);
}
LOG_VERBOSE("[%s] event was received. Payload => %s\n", callbackInfo->eventName, buffer.getLength() ? *buffer : "EMPTY");
if (strcmp(callbackInfo->eventName, "Command") == 0) {
LOG_VERBOSE("Command name was => %s\r\n", callbackInfo->tag);
executeCommand(callbackInfo->tag, *buffer);
}
}
void setup() {
delay(2000);
Serial.begin(115200);
Serial.println("It begins");
if (!connectWiFi()) {
while(1)
;
}
// Prepare LED on WROVER
pinMode(0, OUTPUT);
pinMode(2, OUTPUT);
pinMode(4, OUTPUT);
// Turn off all LEDs on WROVER
digitalWrite(0, LOW);
digitalWrite(2, LOW);
digitalWrite(4, LOW);
// Add callbacks
iotclient.setCallback(AzureIoTCallbackConnectionStatus, onEvent);
iotclient.setCallback(AzureIoTCallbackMessageSent, onEvent);
iotclient.setCallback(AzureIoTCallbackCommand, onEvent);
iotclient.setCallback(AzureIoTCallbackSettingsUpdated, onEvent);
iotclient.begin(&iotconfig);
}
unsigned long lastTick = 0, loopId = 0;
void loop() {
if (!iotclient.run()) {
return; //No point to continue
}
unsigned long ms = millis();
if (ms - lastTick > 15000) { // send telemetry every 10 seconds
char msg[64] = {0};
int pos = 0;
bool errorCode = false;
lastTick = ms;
// Randomize to simulate temperature
long tempVal = random(35, 40);
// Send telemetry
if (tempVal >= 38) {
pos = snprintf(msg, sizeof(msg) - 1, R"({"temperature": %.2f, "temperatureAlert": %d})", tempVal*1.0f, (tempVal >= 38));
msg[pos] = 0;
errorCode = iotclient.sendTelemetry(msg, pos);
} else {
pos = snprintf(msg, sizeof(msg) - 1, "{\"temperature\": %.2f}", tempVal*1.0f);
msg[pos] = 0;
errorCode = iotclient.sendTelemetry(msg, pos);
}
if (!errorCode) {
LOG_ERROR("Sending message has failed");
}
if (!errorCode) {
LOG_ERROR("Sending message has failed with error code %d", errorCode);
}
}
}To invoke direct method of the device from the cloud, in this example, using VSCode, here's the flow:
- Significant amount of code is adapted from here.
- PubSubClient is changed and bundled in this repo.