diff --git a/ESP-IDF_Robot_RC/main/espnow_example.h b/ESP-IDF_Robot_RC/main/espnow_example.h
index 40b7366d7..daca46ae6 100755
--- a/ESP-IDF_Robot_RC/main/espnow_example.h
+++ b/ESP-IDF_Robot_RC/main/espnow_example.h
@@ -79,6 +79,7 @@ typedef struct {
 } __attribute__((packed)) sensors_data_t;
 
 typedef struct {
+    int len;                                // Length of ESPNOW data to be sent, unit: byte.
     uint8_t     *buffer;                      // Buffer; pointer to the data struct.
     uint8_t     dest_mac[ESP_NOW_ETH_ALEN]; // MAC address of destination device.
 } espnow_data_packet_t;
diff --git a/ESP-IDF_Robot_RC/main/espnow_example_main.c b/ESP-IDF_Robot_RC/main/espnow_example_main.c
index be39cfb58..a9d280e77 100755
--- a/ESP-IDF_Robot_RC/main/espnow_example_main.c
+++ b/ESP-IDF_Robot_RC/main/espnow_example_main.c
@@ -436,9 +436,9 @@ void deletePeer (void) {
 /* Prepare ESPNOW data to be sent. */
 void sensors_data_prepare(espnow_data_packet_t *send_param)
 {
-    sensors_data_t *buffer = (example_espnow_data_t *)send_param->buffer;
+    sensors_data_t *buffer = (sensors_data_t *)send_param->buffer;
 
-    assert(send_param->len >= sizeof(example_espnow_data_t));
+    assert(send_param->len >= sizeof(sensors_data_t));
 
     buf->type = 1; // UNICAST IS_BROADCAST_ADDR(send_param->dest_mac) ? EXAMPLE_ESPNOW_DATA_BROADCAST : EXAMPLE_ESPNOW_DATA_UNICAST;
     buf->state = send_param->state;