Im trying to send a JSON doc from an UNO to ESP over serial and then publish it over MQTT.
I am having trouble with storing the JSON doc serial message as a character array to then publish.
UNO code
#include <ArduinoJson.h>
#include <DHT.h>
#define DHTPIN 4 // what pin we're connected to
#define DHTTYPE DHT22 // DHT 22 (AM2302)
DHT dht(DHTPIN, DHTTYPE); //// Initialize DHT sensor for normal 16mhz Arduino
String message = "";
bool messageReady = false;
void setup() {
Serial.begin(115200);
dht.begin();
}
void loop() {
// Monitor serial communication
while(Serial.available()) {
message = Serial.readString();
messageReady = true;
}
// Only process message if there's one
if(messageReady) {
// The only messages we'll parse will be formatted in JSON
DynamicJsonDocument doc(1024); // ArduinoJson version 6+
// Attempt to deserialize the message
DeserializationError error = deserializeJson(doc,message);
if(error) {
Serial.print(F("deserializeJson() failed: "));
Serial.println(error.c_str());
messageReady = false;
return;
}
if(doc["type"] == "request") {
doc["type"] = "response";
// Get data from analog sensors
doc["Humidity"] = dht.readHumidity();
doc["Temperature"] = dht.readTemperature();
serializeJson(doc,Serial);
}
messageReady = false;
}
}
ESP code
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
// Update these with values suitable for your network.
const char* ssid = "";
const char* password = "";
const char* mqtt_server = "";
WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE (50)
char msg[MSG_BUFFER_SIZE];
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
// Switch on the LED if an 1 was received as first character
if ((char)payload[0] == '1') {
digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
// but actually the LED is on; this is because
// it is active low on the ESP-01)
} else {
digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
}
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("Topic", "hello world");
// ... and resubscribe
client.subscribe("Topic");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
unsigned long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
handleIndex();
}
}
void handleIndex()
{
// Send a JSON-formatted request with key "type" and value "request"
// then parse the JSON-formatted response with keys "gas" and "distance"
DynamicJsonDocument doc(1024);
double Temperature = 0, Humidity = 0;
// Sending the request
doc["type"] = "request";
serializeJson(doc, Serial);
////////////////////////THIS PART HERE/////////////////////
// Reading the response
boolean messageReady = false;
String message = "";
while (messageReady == false) { // blocking but that's ok
if (Serial.available()) {
message = Serial.readString();
messageReady = true;
}
}
char buffer[256];
serializeJson(doc, buffer);
if (client.publish("Topic", buffer)) {
Serial.println("Publish ok");
}
else {
Serial.println("Publish failed");
}
}
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
// Update these with values suitable for your network.
const char* ssid = "";
const char* password = "";
const char* mqtt_server = "";
WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE (50)
char msg[MSG_BUFFER_SIZE];
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
// Switch on the LED if an 1 was received as first character
if ((char)payload[0] == '1') {
digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
// but actually the LED is on; this is because
// it is active low on the ESP-01)
} else {
digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
}
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("Topic", "hello world");
// ... and resubscribe
client.subscribe("PCTopic");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
unsigned long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
handleIndex();
}
}
void handleIndex()
{
// Send a JSON-formatted request with key "type" and value "request"
// then parse the JSON-formatted response with keys "gas" and "distance"
DynamicJsonDocument doc(1024);
double Temperature = 0, Humidity = 0;
// Sending the request
doc["type"] = "request";
serializeJson(doc, Serial);
// Reading the response
boolean messageReady = false;
String message = "";
while (messageReady == false) { // blocking but that's ok
if (Serial.available()) {
message = Serial.readString();
messageReady = true;
}
}
char buffer[256];
message.toCharArray(buffer, 256);
serializeJson(doc, buffer);
if (client.publish("Topic", buffer)) {
Serial.println("Publish ok");
}
else {
Serial.println("Publish failed");
}
}
This is what i get from the MQTT server {"type":"request"}Publish ok {"type":"request"}Publish ok {"type":"request"}Publish ok {"type":"request"}Publish ok {"type":"request"}Publish ok The serial monitor on the UNO deserializeJson() failed: InvalidInput deserializeJson() failed: InvalidInput {"⸮ ":null,"Humidity":51.8,"Temperature":24.1}deserializeJson() failed: InvalidInput {"⸮ ":null,"Humidity":50.8,"Temperature":24}deserializeJson() failed: InvalidInput deserializeJson() failed: InvalidInput
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
// Update these with values suitable for your network.
const char* ssid = "";
const char* password = "";
const char* mqtt_server = "";
WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE (50)
char msg[MSG_BUFFER_SIZE];
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
randomSeed(micros());
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void callback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println();
// Switch on the LED if an 1 was received as first character
if ((char)payload[0] == '1') {
digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
// but actually the LED is on; this is because
// it is active low on the ESP-01)
} else {
digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
}
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str())) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("Topic", "hello world");
// ... and resubscribe
client.subscribe("PCTopic");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
unsigned long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
handleIndex();
}
}
void handleIndex()
{
// Send a JSON-formatted request with key "type" and value "request"
// then parse the JSON-formatted response with keys "gas" and "distance"
DynamicJsonDocument doc(1024);
double Temperature = 0, Humidity = 0;
// Sending the request
doc["type"] = "request";
serializeJson(doc, Serial);
// Reading the response
boolean messageReady = false;
String message = "";
while (messageReady == false) { // blocking but that's ok
if (Serial.available()) {
message = Serial.readString();
messageReady = true;
}
}
client.publish("Topic", message.c_str());
MQTT Server
{"W":null,"Humidity":51.4,"Temperature":24}
{"W":null,"Humidity":50.8,"Temperature":24}