C2D messaging in Azure Web CLI (bash)
az iot device c2d-message send -d MY-DEVICE-NAME -n MY-IOT-HUB-NAME --data "It works"
This works - a C2D message is sent to the device. The message is printed out over serial, and is displayed on a TFT.
When I submit an HTTP request no message is received on the target device. I'll include the relevant device code at the very bottom.
Is there a difference between a C2D message using az iot device c2d-message send and using the HTTP request below?
HTTP request
curl -i https://MY-IOT-HUB-NAME.azure-devices.net/devices/MY-DEVICE-NAME/messages/events?api-version=2016-11-14 -H "Authorization: SharedAccessSignature sr=MY-IOT-HUB-NAME.azure-devices.net&sig=MY-SAS-SIG&se=1613476202&skn=MY-SKN" -H "Content-Type: application/json" -d'{"deviceId":"MY-DEVICE-NAME","temperature":70}'
This HTTP request is working, and I'm getting a 204, which indicates that that the HTTP request is properly formed and the authorisation is working. The response is below.
Response
HTTP/1.1 204 No Content
Content-Length: 0
Server: Microsoft-HTTPAPI/2.0
x-ms-request-id: 7d78e812-9659-4b70-aed2-becd81410192
Date: Tue, 16 Feb 2021 11:20:43 GMT
Device code
Apologies for my sloppy code, I'm new to C++.
#include <AzureIoTHub.h>
#include "AzureIoTProtocol_MQTT.h"
#include "Esp.h"
#include "Free_Fonts.h"
#include <iothub_client_ll.h>
#include "iot_configs.h"
#include "iothubtransportmqtt.h"
#include "sample_init.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "SPI.h"
#include "TFT_eSPI.h"
#include <Wire.h>
static const char ssid[] = IOT_CONFIG_WIFI_SSID;
static const char pass[] = IOT_CONFIG_WIFI_PASSWORD;
static const char* connectionString = DEVICE_CONNECTION_STRING;
static bool g_continueRunning = true;
static size_t g_message_count_send_confirmations = 0;
IOTHUB_MESSAGE_HANDLE message_handle;
IOTHUB_CLIENT_STATUS status;
size_t messages_sent = 0;
int message_frequency = 10000;
TFT_eSPI tft = TFT_eSPI();
unsigned long drawTime = 0;
int row = 0;
int rows = 15;
int linespace = 16;
int padding = 2;
int counter = 0;
int chars = 29;
int result = 0;
IOTHUB_DEVICE_CLIENT_LL_HANDLE device_ll_handle;
static int callbackCounter;
int receiveContext = 0;
void setup() {
Serial.begin(115200);
tft.begin();
tft.setRotation(1);
tft.fillScreen(TFT_BLACK);
logger("Connecting to WiFi...", "ALERT", true, true);
logger(IOT_CONFIG_WIFI_SSID, "ALERT", true, true);
sample_init(ssid, pass);
logger("Connected to WiFi", "ALERT", true, true);
IOTHUB_CLIENT_TRANSPORT_PROVIDER protocol = MQTT_Protocol;
logger("Connecting to IoT Hub...", "ALERT", true, true);
(void)IoTHub_Init();
logger("Connected to IoT Hub", "ALERT", true, true);
device_ll_handle = IoTHubDeviceClient_LL_CreateFromConnectionString(connectionString, protocol);
logger("Creating device handle...", "ALERT", true, true);
IoTHubClient_LL_SetMessageCallback(device_ll_handle, ReceiveMessageCallback, NULL);
logger("Created device handle", "ALERT", true, true);
logger("Ready to receive C2D msgs", "ALERT", true, true);
logger("", "ALERT", true, true);
do
{
IoTHubClient_LL_DoWork(device_ll_handle);
ThreadAPI_Sleep(1);
} while (1);
IoTHubClient_LL_Destroy(device_ll_handle);
IoTHub_Deinit();
}
static IOTHUBMESSAGE_DISPOSITION_RESULT ReceiveMessageCallback(IOTHUB_MESSAGE_HANDLE message, void* userContextCallback)
{
const unsigned char* buffer = NULL;
size_t size = 0;
char m_buffer[1000]; // need to work out my max buffer size and deal with this - if I send a longer message it will break!
int m = sprintf(m_buffer, "msg: %d", counter);
char niceBuffer[30] = {
0
};
(void)userContextCallback;
IoTHubMessage_GetByteArray(message, &buffer, &size);
printf("Received Message: %.*s & Size=%d\r\n", (int)size, buffer, (int)size);
if (size > chars) {
size = chars;
}
for (int i = 0; i < size; i++) {
niceBuffer[i] = buffer[i];
}
niceBuffer[chars] = '\0';
logger(niceBuffer, "ALERT", true, true);
delay(1000);
counter++;
return IOTHUBMESSAGE_ACCEPTED;
}
void logger(const char * message,
const char * type, bool print_to_serial, bool print_to_display) {
if (print_to_serial) {
Serial.println(message);
} else {
}
if (print_to_display) {
// TODO 2D data for the screen
if (row == rows) {
tft.fillScreen(TFT_BLACK);
row = 0;
}
tft.setTextDatum(TL_DATUM);
tft.setTextColor(TFT_WHITE, TFT_BLACK);
tft.setFreeFont(FF1);
tft.drawString(message, padding, (padding + (linespace * row)), GFXFF);
row++;
} else {
}
}
void loop() {
//loop
}
#ifndef LOAD_GLCD
//ERROR_Please_enable_LOAD_GLCD_in_User_Setup
#endif
#ifndef LOAD_GFXFF
ERROR_Please_enable_LOAD_GFXFF_in_User_Setup!
#endif
