Combo Module Bluetooth Distribution Network Protocol

Note：This protocol does not require MCU participation.

Version

Date	Version	Description
2022.11.16	V0.1	Initial Version

1.Bluetooth broadcast packet specification

The Bluetooth broadcast packet format follows the Bluetooth 4.0 specification and consists of several AD Structures (see Bluetooth 4.2 Core Specification, Volume 3, Part C, Chapter 11), each of which consists of Length, AD Type, and ADData.

As shown in the following figure:

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1.1 Bluetooth broadcast package content

Broadcast packet standard data segment:

TYPE	LEN	VALUE
0x01（flags）	0x02	0x06
0x03（service uuid）	0x03	0x0922
0x09（Local name）	0x03	"MX"
0xFF（manufacture data）	0x13	Custom data segments

Custom data segments

Custom data segments
Endian	Content
byte[0]--byte[1]	Company ID
byte[2]	MASK
byte[3]--byte[8]	MAC地址
byte[9]--byte[17]	9 bytes, users can configure: AT+STARTSMART=6, hexstring The longest hexstring is 18 bytes, which is the hexstring data of this broadcast content.

Remarks:

1. MASK: Function enable mask, specifying functions in bit order

2. Product ID, Product ID, Product ID is a 6-digit string, fixed as ascii "000000"

Bit序	Function Description
1~0	(reserved) Bluetooth version, 00:BLE4.0; 01: BLE4.2; 10: BLE5.0; 11: BLE5.0 or above
2	Distribution network status identifier, 0: non distribution network status; 1: Distribution network status
3	0: No security authentication is required; 1: Conduct security certification
4	0: Do not encrypt data transmission; 1: Encrypt data transmission
7~5	Keep for future use, fill in all zeros

2.Bluetooth connection service

The service declaration is Primary Service, and the Service UUID is 0x0922

2.1 Characteristics Description

The service includes the following 2 characteristics.

Characteristics Name	Write Characteristics	Notify Characteristics
Characteristics UUID	0xAAB1	0xAAB2
Requirement	Mandatory	Mandatory
Properties	Write	Notify
Permission	Write	None
Notes	APP -> WiFi	WiFi -> APP

2.2 Protocol frame

Protocol Detail	Raw Data	Encrypted Data
	JSON	sdfhisdhfs=dhldjkfhslhf

2.2.1 SAR Subcontracting method

If a packet length is greater than MTU, it needs to be sent in shards, and the corresponding receiver needs to reassemble these sharded messages.

This agreement is based on the sharding and reassembly mechanism of the Mesh GATT Bear layer, and the packet format is as follows:

SAR	Data
Octet 0	Octet 1	Octet 2	......	Octet n

SAR Explanation：

Value	Description
0x00	Complete Data Package
0x01	Fragmented packet 1
0x10	Packet 2~n of sharded data
0x11	Last packet of sharded data packet

2.2.2 Raw Data

The raw data is in JSON format, and the JSON packet must include the key value: Type. After receiving the Bluetooth packet in its entirety, the module first determines the Type and processes the data based on it. The Type value is as follows:

Key	Value	Description
Type	apinfo	WiFi configuration information packet
	wifi_reply	WiFi connection status feedback

2.2.3 apinfo

APP->WiFi

Explanation: The APP sends routing information and other information to the WiFi module.

{
  "type": "apinfo",
  "data": {
    "ssid": "xxx",
    "password": "xxx"
  }
}

2.2.4 wifi_reply

WiFi->APP

Explanation: After receiving apinfo and connecting to the router, the WiFi module responds as connected to the APP. If the connection times out for 30 seconds, the WiFi module will return the reason for the APP failure

{
  "type": "wifi_reply",
  "data": {
    "error_code": 0,
    "describe": "connected"
  }
}

WiFi connection status feedback content description:

JSONKey	error_code	describe
Object	0	connected
	1	ap not found
	2	rssi too low
	3	fail connected

3.Distribution network flowchart

4.Distribution network example

1. The app combines ssid and password to form a JSON package for apinfo

   Convert the JSON package of apinfo to hex format data and add a header. Please determine the header based on the size of the MTU. If not subcontracted, hex data:007B2274797065223A20226170696E666F222C2264617461223A207B2273736964223A202274657374222C2270617373776F7264223A20223132333435363738227D7DAfter connecting to the router, the Wi Fi module will reply with a successful status. Hex data:007B2274797065223A22776966695F7265706C79222C2264617461223A7B226572726F725F636F6465223A302C226465736372696265223A22636F6E6E6563746564227D7DConvert the above hex to JSON format:5.nrf connect test-------------------------------------------------------------------------------End.