e1ab4b6711
example: Remove duplicate commands and invalid serial port information Closes IDFGH-3022 See merge request espressif/esp-idf!8295
120 lines
5.7 KiB
Markdown
120 lines
5.7 KiB
Markdown
| Supported Targets | ESP32 |
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| ----------------- | ----- |
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# ESPNOW Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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This example shows how to use ESPNOW of wifi. Example does the following steps:
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* Start WiFi.
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* Initialize ESPNOW.
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* Register ESPNOW sending or receiving callback function.
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* Add ESPNOW peer information.
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* Send and receive ESPNOW data.
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This example need at least two ESP devices:
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* In order to get the MAC address of the other device, Device1 firstly send broadcast ESPNOW data with 'state' set as 0.
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* When Device2 receiving broadcast ESPNOW data from Device1 with 'state' as 0, adds Device1 into the peer list.
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Then start sending broadcast ESPNOW data with 'state' set as 1.
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* When Device1 receiving broadcast ESPNOW data with 'state' as 1, compares the local magic number with that in the data.
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If the local one is bigger than that one, stop sending broadcast ESPNOW data and starts sending unicast ESPNOW data to Device2.
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* If Device2 receives unicast ESPNOW data, also stop sending broadcast ESPNOW data.
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In practice, if the MAC address of the other device is known, it's not required to send/receive broadcast ESPNOW data first,
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just add the device into the peer list and send/receive unicast ESPNOW data.
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There are a lot of "extras" on top of ESPNOW data, such as type, state, sequence number, CRC and magic in this example. These "extras" are
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not required to use ESPNOW. They are only used to make this example to run correctly. However, it is recommended that users add some "extras"
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to make ESPNOW data more safe and more reliable.
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## How to use example
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### Configure the project
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```
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idf.py menuconfig
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```
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* Set WiFi mode (station or SoftAP) under Example Configuration Options.
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* Set ESPNOW primary master key under Example Configuration Options.
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This parameter must be set to the same value for sending and recving devices.
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* Set ESPNOW local master key under Example Configuration Options.
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This parameter must be set to the same value for sending and recving devices.
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* Set Channel under Example Configuration Options.
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The sending device and the recving device must be on the same channel.
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* Set Send count and Send delay under Example Configuration Options.
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* Set Send len under Example Configuration Options.
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* Set Enable Long Range Options.
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When this parameter is enabled, the ESP32 device will send data at the PHY rate of 512Kbps or 256Kbps
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then the data can be transmitted over long range between two ESP32 devices.
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### Build and Flash
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Build the project and flash it to the board, then run monitor tool to view serial output:
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```
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idf.py -p PORT flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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Here is the example of ESPNOW receiving device console output.
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```
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I (898) phy: phy_version: 3960, 5211945, Jul 18 2018, 10:40:07, 0, 0
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I (898) wifi: mode : sta (30:ae:a4:80:45:68)
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I (898) espnow_example: WiFi started
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I (898) ESPNOW: espnow [version: 1.0] init
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I (5908) espnow_example: Start sending broadcast data
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I (6908) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (7908) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (52138) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (52138) espnow_example: Receive 0th broadcast data from: 30:ae:a4:0c:34:ec, len: 200
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I (53158) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (53158) espnow_example: Receive 1th broadcast data from: 30:ae:a4:0c:34:ec, len: 200
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I (54168) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (54168) espnow_example: Receive 2th broadcast data from: 30:ae:a4:0c:34:ec, len: 200
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I (54168) espnow_example: Receive 0th unicast data from: 30:ae:a4:0c:34:ec, len: 200
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I (54678) espnow_example: Receive 1th unicast data from: 30:ae:a4:0c:34:ec, len: 200
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I (55668) espnow_example: Receive 2th unicast data from: 30:ae:a4:0c:34:ec, len: 200
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```
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Here is the example of ESPNOW sending device console output.
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```
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I (915) phy: phy_version: 3960, 5211945, Jul 18 2018, 10:40:07, 0, 0
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I (915) wifi: mode : sta (30:ae:a4:0c:34:ec)
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I (915) espnow_example: WiFi started
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I (915) ESPNOW: espnow [version: 1.0] init
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I (5915) espnow_example: Start sending broadcast data
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I (5915) espnow_example: Receive 41th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (5915) espnow_example: Receive 42th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (5925) espnow_example: Receive 44th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (5935) espnow_example: Receive 45th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (6965) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (6965) espnow_example: Receive 46th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (7975) espnow_example: send data to ff:ff:ff:ff:ff:ff
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I (7975) espnow_example: Receive 47th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (7975) espnow_example: Start sending unicast data
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I (7975) espnow_example: send data to 30:ae:a4:80:45:68
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I (9015) espnow_example: send data to 30:ae:a4:80:45:68
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I (9015) espnow_example: Receive 48th broadcast data from: 30:ae:a4:80:45:68, len: 200
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I (10015) espnow_example: send data to 30:ae:a4:80:45:68
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I (16075) espnow_example: send data to 30:ae:a4:80:45:68
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I (17075) espnow_example: send data to 30:ae:a4:80:45:68
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I (24125) espnow_example: send data to 30:ae:a4:80:45:68
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```
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## Troubleshooting
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If ESPNOW data can not be received from another device, maybe the two devices are not
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on the same channel or the primary key and local key are different.
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In real application, if the receiving device is in station mode only and it connects to an AP,
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modem sleep should be disabled. Otherwise, it may fail to revceive ESPNOW data from other devices.
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