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Merge branch 'feat/support_longer_data_len_in_espnow' into 'master'

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feat(wifi/espnow): Support longer data length in espnow

Closes IDFGH-7935

See merge request espressif/esp-idf!31097
This commit is contained in:
Jiang Jiang Jian
2024-09-29 16:58:33 +08:00
parent dde0b46390 b4d102796f
commit ee74f278c8
4 changed files with 66 additions and 24 deletions
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37
docs/en/api-reference/network/esp_now.rst
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@@ -13,7 +13,15 @@ CTR with CBC-MAC Protocol (CCMP) is used to protect the action frame for securit
Frame Format
------------
ESP-NOW uses a vendor-specific action frame to transmit ESP-NOW data. The default ESP-NOW bit rate is 1 Mbps. The format of the vendor-specific action frame is as follows:
ESP-NOW uses a vendor-specific action frame to transmit ESP-NOW data. The default ESP-NOW bit rate is 1 Mbps.
Currently, ESP-NOW supports two versions: v1.0 and v2.0. The maximum packet length supported by v2.0 devices is ESP_NOW_MAX_DATA_LEN_V2 bytes, while the maximum packet length supported by v1.0 devices is ESP_NOW_MAX_DATA_LEN bytes.
The v2.0 devices are capable of receiving packets from both v2.0 and v1.0 devices. In contrast, v1.0 devices can only receive packets from other v1.0 devices.
However, v1.0 devices can receive v2.0 packets if the packet length is less than or equal to ESP_NOW_MAX_IE_DATA_LEN.
For packets exceeding this length, the v1.0 devices will either truncate the data to the first ESP_NOW_MAX_IE_DATA_LEN bytes or discard the packet entirely.
For detailed behavior, please refer to the documentation corresponding to the specific IDF version.
The format of the vendor-specific action frame is as follows:
.. highlight:: none
@@ -22,28 +30,39 @@ ESP-NOW uses a vendor-specific action frame to transmit ESP-NOW data. The defaul
------------------------------------------------------------------------------------------------------------
| MAC Header | Category Code | Organization Identifier | Random Values | Vendor Specific Content | FCS |
------------------------------------------------------------------------------------------------------------
24 bytes 1 byte 3 bytes 4 bytes 7-257 bytes 4 bytes
24 bytes 1 byte 3 bytes 4 bytes 7-x bytes 4 bytes
- Category Code: The Category Code 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.
- Random Value: The Random Value filed is used to prevents relay attacks.
- Vendor Specific Content: The Vendor Specific Content contains vendor-specific fields as follows:
- Vendor Specific Content: The Vendor Specific Content contains several (at least one) vendor-specific element fields. For version v2.0, x = 1532(1490 + 6*7), for version v1.0, x = 257(250 + 7).
The format of the vendor-specific element frame is 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
ESP-NOW v1.0:
------------------------------------------------------------------------------------------
| Element ID | Length | Organization Identifier | Type | Reserved | Version | Body |
------------------------------------------------------------------------------------------
7~4 bits | 3~0 bits
1 byte 1 byte 3 bytes 1 byte 1 byte 0-250 bytes
ESP-NOW v2.0:
-----------------------------------------------------------------------------------------------------
| Element ID | Length | Organization Identifier | Type | Reserved | More data |Version | Body |
-----------------------------------------------------------------------------------------------------
7~5 bits | 1 bit |3~0 bits
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.
- Length: The length is the total length of Organization Identifier, Type, Version and Body, the maximum value is 255.
- 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.
- Body: The Body contains the actual ESP-NOW data to be transmitted.
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).