245 lines
8.2 KiB
C++
245 lines
8.2 KiB
C++
/**
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ESPNOW - Basic communication - Master
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Date: 26th September 2017
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Author: Arvind Ravulavaru <https://github.com/arvindr21>
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Purpose: ESPNow Communication between a Master ESP32 and multiple ESP32 Slaves
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Description: This sketch consists of the code for the Master module.
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Resources: (A bit outdated)
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a. https://espressif.com/sites/default/files/documentation/esp-now_user_guide_en.pdf
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b. http://www.esploradores.com/practica-6-conexion-esp-now/
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<< This Device Master >>
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Flow: Master
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Step 1 : ESPNow Init on Master and set it in STA mode
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Step 2 : Start scanning for Slave ESP32 (we have added a prefix of `slave` to the SSID of slave for an easy setup)
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Step 3 : Once found, add Slave as peer
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Step 4 : Register for send callback
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Step 5 : Start Transmitting data from Master to Slave(s)
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Flow: Slave
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Step 1 : ESPNow Init on Slave
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Step 2 : Update the SSID of Slave with a prefix of `slave`
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Step 3 : Set Slave in AP mode
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Step 4 : Register for receive callback and wait for data
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Step 5 : Once data arrives, print it in the serial monitor
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Note: Master and Slave have been defined to easily understand the setup.
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Based on the ESPNOW API, there is no concept of Master and Slave.
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Any devices can act as master or salve.
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// Sample Serial log with 1 master & 2 slaves
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Found 12 devices
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1: Slave:24:0A:C4:81:CF:A4 [24:0A:C4:81:CF:A5] (-44)
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3: Slave:30:AE:A4:02:6D:CC [30:AE:A4:02:6D:CD] (-55)
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2 Slave(s) found, processing..
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Processing: 24:A:C4:81:CF:A5 Status: Already Paired
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Processing: 30:AE:A4:2:6D:CD Status: Already Paired
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Sending: 9
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Send Status: Success
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Last Packet Sent to: 24:0a:c4:81:cf:a5
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Last Packet Send Status: Delivery Success
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Send Status: Success
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Last Packet Sent to: 30:ae:a4:02:6d:cd
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Last Packet Send Status: Delivery Success
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*/
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#include <esp_now.h>
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#include <WiFi.h>
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// Global copy of slave
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#define NUMSLAVES 20
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esp_now_peer_info_t slaves[NUMSLAVES] = {};
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int SlaveCnt = 0;
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#define CHANNEL 3
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#define PRINTSCANRESULTS 0
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// Init ESP Now with fallback
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void InitESPNow() {
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WiFi.disconnect();
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if (esp_now_init() == ESP_OK) {
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Serial.println("ESPNow Init Success");
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}
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else {
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Serial.println("ESPNow Init Failed");
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// Retry InitESPNow, add a counte and then restart?
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// InitESPNow();
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// or Simply Restart
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ESP.restart();
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}
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}
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// Scan for slaves in AP mode
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void ScanForSlave() {
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int8_t scanResults = WiFi.scanNetworks();
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//reset slaves
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memset(slaves, 0, sizeof(slaves));
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SlaveCnt = 0;
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Serial.println("");
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if (scanResults == 0) {
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Serial.println("No WiFi devices in AP Mode found");
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} else {
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Serial.print("Found "); Serial.print(scanResults); Serial.println(" devices ");
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for (int i = 0; i < scanResults; ++i) {
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// Print SSID and RSSI for each device found
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String SSID = WiFi.SSID(i);
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int32_t RSSI = WiFi.RSSI(i);
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String BSSIDstr = WiFi.BSSIDstr(i);
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if (PRINTSCANRESULTS) {
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Serial.print(i + 1); Serial.print(": "); Serial.print(SSID); Serial.print(" ["); Serial.print(BSSIDstr); Serial.print("]"); Serial.print(" ("); Serial.print(RSSI); Serial.print(")"); Serial.println("");
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}
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delay(10);
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// Check if the current device starts with `Slave`
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if (SSID.indexOf("Slave") == 0) {
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// SSID of interest
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Serial.print(i + 1); Serial.print(": "); Serial.print(SSID); Serial.print(" ["); Serial.print(BSSIDstr); Serial.print("]"); Serial.print(" ("); Serial.print(RSSI); Serial.print(")"); Serial.println("");
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// Get BSSID => Mac Address of the Slave
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int mac[6];
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if ( 6 == sscanf(BSSIDstr.c_str(), "%x:%x:%x:%x:%x:%x", &mac[0], &mac[1], &mac[2], &mac[3], &mac[4], &mac[5] ) ) {
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for (int ii = 0; ii < 6; ++ii ) {
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slaves[SlaveCnt].peer_addr[ii] = (uint8_t) mac[ii];
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}
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}
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slaves[SlaveCnt].channel = CHANNEL; // pick a channel
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slaves[SlaveCnt].encrypt = 0; // no encryption
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SlaveCnt++;
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}
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}
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}
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if (SlaveCnt > 0) {
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Serial.print(SlaveCnt); Serial.println(" Slave(s) found, processing..");
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} else {
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Serial.println("No Slave Found, trying again.");
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}
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// clean up ram
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WiFi.scanDelete();
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}
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// Check if the slave is already paired with the master.
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// If not, pair the slave with master
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void manageSlave() {
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if (SlaveCnt > 0) {
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for (int i = 0; i < SlaveCnt; i++) {
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Serial.print("Processing: ");
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for (int ii = 0; ii < 6; ++ii ) {
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Serial.print((uint8_t) slaves[i].peer_addr[ii], HEX);
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if (ii != 5) Serial.print(":");
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}
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Serial.print(" Status: ");
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// check if the peer exists
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bool exists = esp_now_is_peer_exist(slaves[i].peer_addr);
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if (exists) {
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// Slave already paired.
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Serial.println("Already Paired");
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} else {
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// Slave not paired, attempt pair
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esp_err_t addStatus = esp_now_add_peer(&slaves[i]);
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if (addStatus == ESP_OK) {
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// Pair success
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Serial.println("Pair success");
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} else if (addStatus == ESP_ERR_ESPNOW_NOT_INIT) {
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// How did we get so far!!
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Serial.println("ESPNOW Not Init");
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} else if (addStatus == ESP_ERR_ESPNOW_ARG) {
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Serial.println("Add Peer - Invalid Argument");
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} else if (addStatus == ESP_ERR_ESPNOW_FULL) {
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Serial.println("Peer list full");
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} else if (addStatus == ESP_ERR_ESPNOW_NO_MEM) {
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Serial.println("Out of memory");
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} else if (addStatus == ESP_ERR_ESPNOW_EXIST) {
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Serial.println("Peer Exists");
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} else {
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Serial.println("Not sure what happened");
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}
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delay(100);
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}
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}
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} else {
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// No slave found to process
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Serial.println("No Slave found to process");
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}
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}
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uint8_t data = 0;
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// send data
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void sendData() {
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data++;
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for (int i = 0; i < SlaveCnt; i++) {
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const uint8_t *peer_addr = slaves[i].peer_addr;
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if (i == 0) { // print only for first slave
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Serial.print("Sending: ");
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Serial.println(data);
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}
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esp_err_t result = esp_now_send(peer_addr, &data, sizeof(data));
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Serial.print("Send Status: ");
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if (result == ESP_OK) {
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Serial.println("Success");
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} else if (result == ESP_ERR_ESPNOW_NOT_INIT) {
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// How did we get so far!!
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Serial.println("ESPNOW not Init.");
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} else if (result == ESP_ERR_ESPNOW_ARG) {
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Serial.println("Invalid Argument");
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} else if (result == ESP_ERR_ESPNOW_INTERNAL) {
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Serial.println("Internal Error");
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} else if (result == ESP_ERR_ESPNOW_NO_MEM) {
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Serial.println("ESP_ERR_ESPNOW_NO_MEM");
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} else if (result == ESP_ERR_ESPNOW_NOT_FOUND) {
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Serial.println("Peer not found.");
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} else {
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Serial.println("Not sure what happened");
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}
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delay(100);
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}
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}
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// callback when data is sent from Master to Slave
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void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) {
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char macStr[18];
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snprintf(macStr, sizeof(macStr), "%02x:%02x:%02x:%02x:%02x:%02x",
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mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
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Serial.print("Last Packet Sent to: "); Serial.println(macStr);
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Serial.print("Last Packet Send Status: "); Serial.println(status == ESP_NOW_SEND_SUCCESS ? "Delivery Success" : "Delivery Fail");
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}
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void setup() {
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Serial.begin(115200);
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//Set device in STA mode to begin with
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WiFi.mode(WIFI_STA);
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Serial.println("ESPNow/Multi-Slave/Master Example");
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// This is the mac address of the Master in Station Mode
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Serial.print("STA MAC: "); Serial.println(WiFi.macAddress());
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// Init ESPNow with a fallback logic
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InitESPNow();
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// Once ESPNow is successfully Init, we will register for Send CB to
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// get the status of Trasnmitted packet
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esp_now_register_send_cb(OnDataSent);
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}
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void loop() {
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// In the loop we scan for slave
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ScanForSlave();
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// If Slave is found, it would be populate in `slave` variable
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// We will check if `slave` is defined and then we proceed further
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if (SlaveCnt > 0) { // check if slave channel is defined
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// `slave` is defined
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// Add slave as peer if it has not been added already
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manageSlave();
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// pair success or already paired
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// Send data to device
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sendData();
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} else {
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// No slave found to process
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}
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// wait for 3seconds to run the logic again
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delay(1000);
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}
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