Update ESP-NOW example sketches

Author: nseidle

Firmware/Test Sketches/ESPNOW_Receive/ESPNOW_Receive.ino

@@ -6,46 +6,58 @@
   A receiver does not need to have the broadcastMac added to its peer list. It will receive a broadcast
   no matter what.
 
-  If desired, onDataRecieve should check the received MAC against the list of friendly/paired MACs 
+  If desired, onDataRecieve should check the received MAC against the list of friendly/paired MACs
   in order to throw out broadcasted packets that may not be valid data.
+
+  Add peers
+  Add callback to deal with allowed incoming data
+  Update test sketches
 */
 
 #include <esp_now.h>
-#include <WiFi.h>
+#include <esp_mac.h> //Needed for esp_read_mac()
+#include <WiFi.h> //Needed because ESP-NOW requires WiFi.mode()
 
-void onDataRecieve(const uint8_t *mac_addr, const uint8_t *incomingData, int len)
+void onDataReceive(const esp_now_recv_info *mac, const uint8_t *incomingData, int len)
 {
-  Serial.printf("Bytes received: %d", len);
-  Serial.printf(" from peer: 0x%02X%02X%02X%02X%02X%02X\r\n", mac_addr[0], mac_addr[1], mac_addr[2], mac_addr[3], mac_addr[4], mac_addr[5]);
+  //    typedef struct esp_now_recv_info {
+  //        uint8_t * src_addr;             // Source address of ESPNOW packet
+  //        uint8_t * des_addr;             // Destination address of ESPNOW packet
+  //        wifi_pkt_rx_ctrl_t * rx_ctrl;   // Rx control info of ESPNOW packet
+  //    } esp_now_recv_info_t;
+
+  // Display the packet info
+  Serial.printf(
+    "RX from MAC %02X:%02X:%02X:%02X:%02X:%02X, %d bytes - ",
+    mac->des_addr[0], mac->des_addr[1], mac->des_addr[2], mac->des_addr[3], mac->des_addr[4], mac->des_addr[5],
+    len);
+
+  //Print what was received - it might be binary gobbly-de-gook
+  char toPrint[len + 1];
+  snprintf(toPrint, sizeof(toPrint), "%s", incomingData);
+  Serial.println(toPrint);
 }
 
 void setup()
 {
   Serial.begin(115200);
-  delay(500);
-  Serial.println("Point to Point Receiver - No WiFi");
+  delay(250);
+  Serial.println("Remote to Central - This is Central");
 
-  uint8_t unitMACAddress[6]; //Use MAC address in BT broadcast and display
+  uint8_t unitMACAddress[6];
   esp_read_mac(unitMACAddress, ESP_MAC_WIFI_STA);
-  Serial.print("WiFi MAC Address:");
-  for (int x = 0 ; x < 6 ; x++)
-  {
-    Serial.print(" 0x");
-    if (unitMACAddress[x] < 0x10) Serial.print("0");
-    Serial.print(unitMACAddress[x], HEX);
-  }
-  Serial.println();
+  Serial.printf("Hi! My MAC address is: {0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X}\r\n",
+                unitMACAddress[0], unitMACAddress[1], unitMACAddress[2], unitMACAddress[3], unitMACAddress[4], unitMACAddress[5]);
 
-  // Set device as a Wi-Fi Station
+  //ESP-NOW must have WiFi initialized
   WiFi.mode(WIFI_STA);
 
-  if (esp_now_init() != ESP_OK) {
+  if (esp_now_init() != ESP_OK)
     Serial.println("Error initializing ESP-NOW");
-    return;
-  }
-
-  esp_now_register_recv_cb(onDataRecieve);
+  else
+    Serial.println("ESP-NOW started");
 
+  esp_now_register_recv_cb(onDataReceive);
 }
 
 void loop()
@@ -63,26 +75,19 @@ void loop()
 
 // Add a given MAC address to the peer list
 esp_err_t espnowAddPeer(uint8_t *peerMac)
-{
-  return (espnowAddPeer(peerMac, true)); // Encrypt by default
-}
-
-esp_err_t espnowAddPeer(uint8_t *peerMac, bool encrypt)
 {
   esp_now_peer_info_t peerInfo;
 
   memcpy(peerInfo.peer_addr, peerMac, 6);
   peerInfo.channel = 0;
   peerInfo.ifidx = WIFI_IF_STA;
-  // memcpy(peerInfo.lmk, "RTKProductsLMK56", 16);
-  // peerInfo.encrypt = encrypt;
   peerInfo.encrypt = false;
 
   esp_err_t result = esp_now_add_peer(&peerInfo);
   if (result != ESP_OK)
-  {
-    Serial.printf("Failed to add peer: 0x%02X%02X%02X%02X%02X%02X\r\n", peerMac[0], peerMac[1], peerMac[2],
-                 peerMac[3], peerMac[4], peerMac[5]);
-  }
+    Serial.printf("Failed to add peer: 0x%02X%02X%02X%02X%02X%02X\r\n", peerMac[0], peerMac[1], peerMac[2], peerMac[3], peerMac[4], peerMac[5]);
+  else
+    Serial.printf("Added peer: 0x%02X%02X%02X%02X%02X%02X\r\n", peerMac[0], peerMac[1], peerMac[2], peerMac[3], peerMac[4], peerMac[5]);
+
   return (result);
 }

Firmware/Test Sketches/ESPNOW_Transmit/ESPNOW_Transmit.ino

@@ -1,26 +1,34 @@
 /*
-  Transmit dummy data over ESP-NOW
+  ESP-NOW tranmit to a specific peer
+  By: Nathan Seidle
+  SparkFun Electronics
+  Date: September 25th, 2025
+  License: Public domain / don't care.
 
-  In this example, we don't have a paired MAC, this example simply broadcasts.
+  In this example we transmit 'hello world' to a specified peer.
 
-  To send a broadcast, the 0xFF broadcastMac has to be added to the peer list, *and*
-  we have to address the message to the broadcastMac, *not* 0 to send to all peers on the list.
+  Run ESPNOW_Transmit and ESPNOW_Recieve on two ESP32s. This example uses Broadcast ESP-NOW
+  so no MAC addresses should be needed. ESP-NOW communication should flow correctly between the two units.
+
+  If you assign a remote MAC, once data is flowing, hold the remote in reset to see the delivery failures.
 
-  A receiver does not need to have the broadcastMac added to its peer list. It will receive a broadcast
-  no matter what.
 */
 
 #include <esp_now.h>
-#include <WiFi.h>
+#include <esp_mac.h> //Needed for esp_read_mac()
+#include <WiFi.h> //Needed because ESP-NOW requires WiFi.mode()
 
 uint8_t broadcastMac[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
-uint8_t roverMac[] = {0x64, 0xB7, 0x08, 0x3D, 0xFD, 0xAC};
+uint8_t remoteMac[] = {0xB8, 0xD6, 0x1A, 0x0C, 0xA3, 0xDC}; //Modify this with the MAC address of the remote unit you want to transmit to
 uint8_t mockMac[] = {0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF}; //Dummy MAC for testing
 
 esp_now_peer_info_t peerInfo;
 
 unsigned long lastSend = 0;
 
+int channelNumber = 0;
+uint8_t packetCounter = 0; // Intentionally 8-bit so it rolls over
+
 void onDataSent(const uint8_t *mac_addr, esp_now_send_status_t status)
 {
   Serial.print("Last Packet Send Status: ");
@@ -33,9 +41,15 @@ void onDataSent(const uint8_t *mac_addr, esp_now_send_status_t status)
 void setup()
 {
   Serial.begin(115200);
-  delay(500);
-  Serial.println("Point to Point - Base Transmitter");
+  delay(250);
+  Serial.println("Remote to Central - This is Remote Transmitter");
 
+  uint8_t unitMACAddress[6];
+  esp_read_mac(unitMACAddress, ESP_MAC_WIFI_STA);
+  Serial.printf("Hi! My MAC address is: {0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X, 0x%02X}\r\n",
+                unitMACAddress[0], unitMACAddress[1], unitMACAddress[2], unitMACAddress[3], unitMACAddress[4], unitMACAddress[5]);
+
+  //ESP-NOW must have WiFi initialized
   WiFi.mode(WIFI_STA);
 
   if (esp_now_init() != ESP_OK) {
@@ -45,27 +59,28 @@ void setup()
 
   esp_now_register_send_cb(onDataSent);
 
-  //espnowAddPeer(roverMac); // Register a remote address if we want to deliver data there
+  //espnowAddPeer(remoteMac); // Register a remote address to deliver data to
   espnowAddPeer(mockMac);
-  espnowAddPeer(broadcastMac);
+  espnowAddPeer(broadcastMac); //Remote this line to remove broadcast transmissions
 }
 
 void loop()
 {
-  if (millis() - lastSend > 500)
+  if (millis() - lastSend > 1000)
   {
     lastSend = millis();
 
-    uint8_t espnowData[] = "This is the test string.";
+    char espnowData[100];
+    sprintf(espnowData, "This is test #: %d", packetCounter++);
 
     esp_err_t result = ESP_OK;
 
-    result = esp_now_send(0, (uint8_t *)&espnowData, sizeof(espnowData)); // Send packet to all peers on the list, excluding broadcast peer.
-    //result = esp_now_send(broadcastMac, (uint8_t *)&espnowData, sizeof(espnowData)); // Send packet over broadcast
-    //result = esp_now_send(roverMac, (uint8_t *)&espnowData, sizeof(espnowData)); // Send packet to a specific peer
+    //result = esp_now_send(0, (uint8_t *)&espnowData, strlen(espnowData)); // Send packet to all peers on the list, excluding broadcast peer.
+    //result = esp_now_send(broadcastMac, (uint8_t *)&espnowData, strlen(espnowData)); // Send packet over broadcast
+    result = esp_now_send(remoteMac, (uint8_t *)&espnowData, strlen(espnowData)); // Send packet to a specific peer
 
     if (result == ESP_OK)
-      Serial.println("Sent with success");
+      Serial.println("Sent with success"); // We will always get a success with broadcastMac packets, presumably because they do not have delivery confirmation.
     else
       Serial.println("Error sending the data");
   }
@@ -81,28 +96,19 @@ void loop()
   }
 }
 
-// Add a given MAC address to the peer list
 esp_err_t espnowAddPeer(uint8_t *peerMac)
-{
-  return (espnowAddPeer(peerMac, true)); // Encrypt by default
-}
-
-esp_err_t espnowAddPeer(uint8_t *peerMac, bool encrypt)
 {
   esp_now_peer_info_t peerInfo;
 
   memcpy(peerInfo.peer_addr, peerMac, 6);
   peerInfo.channel = 0;
   peerInfo.ifidx = WIFI_IF_STA;
-  // memcpy(peerInfo.lmk, "RTKProductsLMK56", 16);
-  // peerInfo.encrypt = encrypt;
   peerInfo.encrypt = false;
 
   esp_err_t result = esp_now_add_peer(&peerInfo);
   if (result != ESP_OK)
   {
-    Serial.printf("Failed to add peer: 0x%02X%02X%02X%02X%02X%02X\r\n", peerMac[0], peerMac[1], peerMac[2],
-                 peerMac[3], peerMac[4], peerMac[5]);
+    Serial.printf("Failed to add peer: 0x%02X%02X%02X%02X%02X%02X\r\n", peerMac[0], peerMac[1], peerMac[2], peerMac[3], peerMac[4], peerMac[5]);
   }
   return (result);
-}
+}