--- /dev/null
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef __ESP_NOW_H__
+#define __ESP_NOW_H__
+
+#include <stdbool.h>
+#include "esp_err.h"
+#include "esp_wifi_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** \defgroup WiFi_APIs WiFi Related APIs
+ * @brief WiFi APIs
+ */
+
+/** @addtogroup WiFi_APIs
+ * @{
+ */
+
+/** \defgroup ESPNOW_APIs ESPNOW APIs
+ * @brief ESP32 ESPNOW APIs
+ *
+ */
+
+/** @addtogroup ESPNOW_APIs
+ * @{
+ */
+
+#define ESP_ERR_ESPNOW_BASE (ESP_ERR_WIFI_BASE + 101) /*!< ESPNOW error number base. */
+#define ESP_ERR_ESPNOW_NOT_INIT (ESP_ERR_ESPNOW_BASE) /*!< ESPNOW is not initialized. */
+#define ESP_ERR_ESPNOW_ARG (ESP_ERR_ESPNOW_BASE + 1) /*!< Invalid argument */
+#define ESP_ERR_ESPNOW_NO_MEM (ESP_ERR_ESPNOW_BASE + 2) /*!< Out of memory */
+#define ESP_ERR_ESPNOW_FULL (ESP_ERR_ESPNOW_BASE + 3) /*!< ESPNOW peer list is full */
+#define ESP_ERR_ESPNOW_NOT_FOUND (ESP_ERR_ESPNOW_BASE + 4) /*!< ESPNOW peer is not found */
+#define ESP_ERR_ESPNOW_INTERNAL (ESP_ERR_ESPNOW_BASE + 5) /*!< Internal error */
+#define ESP_ERR_ESPNOW_EXIST (ESP_ERR_ESPNOW_BASE + 6) /*!< ESPNOW peer has existed */
+
+#define ESP_NOW_ETH_ALEN 6 /*!< Length of ESPNOW peer MAC address */
+#define ESP_NOW_KEY_LEN 16 /*!< Length of ESPNOW peer local master key */
+
+#define ESP_NOW_MAX_TOTAL_PEER_NUM 20 /*!< Maximum number of ESPNOW total peers */
+#define ESP_NOW_MAX_ENCRYPT_PEER_NUM 6 /*!< Maximum number of ESPNOW encrypted peers */
+
+#define ESP_NOW_MAX_DATA_LEN 250 /*!< Maximum length of ESPNOW data which is sent very time */
+
+/**
+ * @brief Status of sending ESPNOW data .
+ */
+typedef enum {
+ ESP_NOW_SEND_SUCCESS = 0, /**< Send ESPNOW data successfully */
+ ESP_NOW_SEND_FAIL, /**< Send ESPNOW data fail */
+} esp_now_send_status_t;
+
+/**
+ * @brief ESPNOW peer information parameters.
+ */
+typedef struct esp_now_peer_info {
+ uint8_t peer_addr[ESP_NOW_ETH_ALEN]; /**< ESPNOW peer MAC address that is also the MAC address of station or softap */
+ uint8_t lmk[ESP_NOW_KEY_LEN]; /**< ESPNOW peer local master key that is used to encrypt data */
+ uint8_t channel; /**< Wi-Fi channel that peer uses to send/receive ESPNOW data. If the value is 0,
+ use the current channel which station or softap is on. Otherwise, it must be
+ set as the channel that station or softap is on. */
+ wifi_interface_t ifidx; /**< Wi-Fi interface that peer uses to send/receive ESPNOW data */
+ bool encrypt; /**< ESPNOW data that this peer sends/receives is encrypted or not */
+ void *priv; /**< ESPNOW peer private data */
+} esp_now_peer_info_t;
+
+/**
+ * @brief Number of ESPNOW peers which exist currently.
+ */
+typedef struct esp_now_peer_num {
+ int total_num; /**< Total number of ESPNOW peers, maximum value is ESP_NOW_MAX_TOTAL_PEER_NUM */
+ int encrypt_num; /**< Number of encrypted ESPNOW peers, maximum value is ESP_NOW_MAX_ENCRYPT_PEER_NUM */
+} esp_now_peer_num_t;
+
+/**
+ * @brief Callback function of receiving ESPNOW data
+ * @param mac_addr peer MAC address
+ * @param data received data
+ * @param data_len length of received data
+ */
+typedef void (*esp_now_recv_cb_t)(const uint8_t *mac_addr, const uint8_t *data, int data_len);
+
+/**
+ * @brief Callback function of sending ESPNOW data
+ * @param mac_addr peer MAC address
+ * @param status status of sending ESPNOW data (succeed or fail)
+ */
+typedef void (*esp_now_send_cb_t)(const uint8_t *mac_addr, esp_now_send_status_t status);
+
+/**
+ * @brief Initialize ESPNOW function
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_INTERNAL : Internal error
+ */
+esp_err_t esp_now_init(void);
+
+/**
+ * @brief De-initialize ESPNOW function
+ *
+ * @return
+ * - ESP_OK : succeed
+ */
+esp_err_t esp_now_deinit(void);
+
+/**
+ * @brief Get the version of ESPNOW
+ *
+ * @param version ESPNOW version
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ */
+esp_err_t esp_now_get_version(uint32_t *version);
+
+/**
+ * @brief Register callback function of receiving ESPNOW data
+ *
+ * @param cb callback function of receiving ESPNOW data
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_INTERNAL : internal error
+ */
+esp_err_t esp_now_register_recv_cb(esp_now_recv_cb_t cb);
+
+/**
+ * @brief Unregister callback function of receiving ESPNOW data
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ */
+esp_err_t esp_now_unregister_recv_cb(void);
+
+/**
+ * @brief Register callback function of sending ESPNOW data
+ *
+ * @param cb callback function of sending ESPNOW data
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_INTERNAL : internal error
+ */
+esp_err_t esp_now_register_send_cb(esp_now_send_cb_t cb);
+
+/**
+ * @brief Unregister callback function of sending ESPNOW data
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ */
+esp_err_t esp_now_unregister_send_cb(void);
+
+/**
+ * @brief Send ESPNOW data
+ *
+ * @attention 1. If peer_addr is not NULL, send data to the peer whose MAC address matches peer_addr
+ * @attention 2. If peer_addr is NULL, send data to all of the peers that are added to the peer list
+ * @attention 3. The maximum length of data must be less than ESP_NOW_MAX_DATA_LEN
+ * @attention 4. The buffer pointed to by data argument does not need to be valid after esp_now_send returns
+ *
+ * @param peer_addr peer MAC address
+ * @param data data to send
+ * @param len length of data
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ * - ESP_ERR_ESPNOW_INTERNAL : internal error
+ * - ESP_ERR_ESPNOW_NO_MEM : out of memory
+ * - ESP_ERR_ESPNOW_NOT_FOUND : peer is not found
+ */
+esp_err_t esp_now_send(const uint8_t *peer_addr, const uint8_t *data, size_t len);
+
+/**
+ * @brief Add a peer to peer list
+ *
+ * @param peer peer information
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ * - ESP_ERR_ESPNOW_FULL : peer list is full
+ * - ESP_ERR_ESPNOW_NO_MEM : out of memory
+ * - ESP_ERR_ESPNOW_EXIST : peer has existed
+ */
+esp_err_t esp_now_add_peer(const esp_now_peer_info_t *peer);
+
+/**
+ * @brief Delete a peer from peer list
+ *
+ * @param peer_addr peer MAC address
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ * - ESP_ERR_ESPNOW_NOT_FOUND : peer is not found
+ */
+esp_err_t esp_now_del_peer(const uint8_t *peer_addr);
+
+/**
+ * @brief Modify a peer
+ *
+ * @param peer peer information
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ * - ESP_ERR_ESPNOW_FULL : peer list is full
+ */
+esp_err_t esp_now_mod_peer(const esp_now_peer_info_t *peer);
+
+/**
+ * @brief Get a peer whose MAC address matches peer_addr from peer list
+ *
+ * @param peer_addr peer MAC address
+ * @param peer peer information
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ * - ESP_ERR_ESPNOW_NOT_FOUND : peer is not found
+ */
+esp_err_t esp_now_get_peer(const uint8_t *peer_addr, esp_now_peer_info_t *peer);
+
+/**
+ * @brief Fetch a peer from peer list
+ *
+ * @param from_head fetch from head of list or not
+ * @param peer peer information
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ * - ESP_ERR_ESPNOW_NOT_FOUND : peer is not found
+ */
+esp_err_t esp_now_fetch_peer(bool from_head, esp_now_peer_info_t *peer);
+
+/**
+ * @brief Peer exists or not
+ *
+ * @param peer_addr peer MAC address
+ *
+ * @return
+ * - true : peer exists
+ * - false : peer not exists
+ */
+bool esp_now_is_peer_exist(const uint8_t *peer_addr);
+
+/**
+ * @brief Get the number of peers
+ *
+ * @param num number of peers
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ */
+esp_err_t esp_now_get_peer_num(esp_now_peer_num_t *num);
+
+/**
+ * @brief Set the primary master key
+ *
+ * @param pmk primary master key
+ *
+ * @attention 1. primary master key is used to encrypt local master key
+ *
+ * @return
+ * - ESP_OK : succeed
+ * - ESP_ERR_ESPNOW_NOT_INIT : ESPNOW is not initialized
+ * - ESP_ERR_ESPNOW_ARG : invalid argument
+ */
+esp_err_t esp_now_set_pmk(const uint8_t *pmk);
+
+/**
+ * @}
+ */
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ESP_NOW_H__ */
--- /dev/null
+ESP-NOW
+======
+
+Overview
+--------
+
+ESP-NOW is a kind of connectionless WiFi communication protocol which is defined by Espressif. In ESP-NOW, application data is
+encapsulated in vendor-specific action frame and then transmitted from one WiFi device to another without connection.
+CTR with CBC-MAC Protocol(CCMP) is used to protect the action frame for security. ESP-NOW is widely used in smart light, remote
+controlling, sensor, etc.
+
+Frame Format
+------------
+
+ESP-NOW uses vendor-specific action frame to transmit ESP-NOW data. The format of vendor-specific action frame is as follows:
+
+.. highlight:: none
+
+::
+
+----------------------------------------------------------------------------------------
+| MAC Header | Category Code | Organization Identifier | Vendor Specific Content | FCS |
+----------------------------------------------------------------------------------------
+ 1 byte 3 bytes 7~255 bytes
+
+- Category Code: The Category field is set to the value(127) indicating the vendor-specific category.
+- Organization Identifier: The Organization Identifier contains a unique identifier(0x18fe34) which is the first three bytes
+ of MAC address applied by Espressif.
+- Vendor Specific Content: The Vendor Specific Content contains vendor-specific field as follows:
+
+.. highlight:: none
+
+::
+
+-------------------------------------------------------------------------------
+| Element ID | Length | Organization Identifier | Type | Version | Body |
+-------------------------------------------------------------------------------
+ 1 byte 1 byte 3 bytes 1 byte 1 byte 0~250 bytes
+
+- Element ID: The Element ID field is set to the value(221) indicating the vendor-specific element.
+- Length: The length is the total length of Organization Identifier, Type, Version and Body.
+- Organization Identifier: The Organization Identifier contains a unique identifier(0x18fe34) which is the first three bytes
+ of MAC address applied by Espressif.
+- Type: The Type field is set to the value(4) indicating ESP-NOW.
+- Version: The Version field is set to the version of ESP-NOW.
+- Body: The Body contains the ESP-NOW data.
+
+As ESP-NOW is connectionless, the MAC header is a little different from that of standard frames. The FromDS and ToDS bits of
+FrameControl field are both 0. The first address field is set to the destination address. The second address field is set to
+the source address. The third address field is set to broadcast address(0xff:0xff:0xff:0xff:0xff:0xff).
+
+Security
+--------
+
+ESP-NOW use CCMP method which can be referenced in IEEE Std. 802.11-2012 to protect the vendor-specific action frame. The WiFi
+device maintains a Primary Master Key(PMK) and several Local Master Keys(LMK). The lengths of them are 16 bytes. PMK is used
+to encrypt LMK with AES-128 algorithm. Call ``esp_now_set_pmk()`` to set PMK. If PMK is not set, a default PMK will be used.
+If LMK of the paired device is set, it will be used to encrypt the vendor-specific action frame with CCMP method. The maximum
+number of different LMKs is six. Do not support encrypting multicast vendor-specific action frame.
+
+Initialization and De-initialization
+------------------------------------
+
+Call ``esp_now_init()`` to initialize ESP-NOW and ``esp_now_deinit()`` to de-initialize ESP-NOW. ESP-NOW data must be transmitted
+after WiFi is started, so it is recommended to start WiFi before initializing ESP-NOW and stop WiFi after de-initializing ESP-NOW.
+When ``esp_now_deinit()`` is called, all of the information of paired devices will be deleted.
+
+Add Paired Device
+-----------------
+
+Before sending data to other device, call ``esp_now_add_peer()`` to add it to the paired device list first. The maximum number of
+paired devices is twenty. If security is enabled, the LMK must be set. ESP-NOW data can be sent from station or softap interface.
+Make sure that the interface is enabled before sending ESP-NOW data. A device with broadcast MAC address must be added before
+sending broadcast data. The range of the channel of paired device is from 0 to 14. If the channel is set to 0, data will be sent
+on the current channel. Otherwise, the channel must be set as the channel that the local device is on.
+
+Send ESP-NOW Data
+-----------------
+
+Call ``esp_now_send()`` to send ESP-NOW data and ``esp_now_register_send_cb`` to register sending callback function. It will return
+`ESP_NOW_SEND_SUCCESS` in sending callback function if the data is received successfully on MAC layer. Otherwise, it will return
+`ESP_NOW_SEND_FAIL`. There are several reasons failing to send ESP-NOW data, for example, the destination device doesn't exist, the
+channels of the devices are not the same, the action frame is lost when transmiting on the air, etc. It is not guaranteed that
+application layer can receive the data. If necessary, send back ack data when receiving ESP-NOW data. If receiving ack data timeout
+happens, retransmit the ESP-NOW data. A sequence number can also be assigned to ESP-NOW data to drop the duplicated data.
+
+If there is a lot of ESP-NOW data to send, call ``esp_now_send()`` to send less than or equal to 250 bytes of data once a time.
+Note that too short interval between sending two ESP-NOW datas may lead to disorder of sending callback function. So, it is
+recommended that sending the next ESP-NOW data after the sending callback function of previous sending has returned. The sending
+callback function runs from a high-priority WiFi task. So, do not do lengthy operations in the callback function. Instead, post
+necessary data to a queue and handle it from a lower priority task.
+
+Receiving ESP-NOW Data
+----------------------
+
+Call ``esp_now_register_recv_cb`` to register receiving callback function. When receiving ESP-NOW data, receiving callback function
+is called. The receiving callback function also runs from WiFi task. So, do not do lengthy operations in the callback function.
+Instead, post necessary data to a queue and handle it from a lower priority task.
+
+API Reference
+-------------
+
+.. include:: /_build/inc/esp_now.inc
projects / esp-idf / commitdiff