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Device communication protocol

Each Solo device Receives and Transmits data. Here's how the communication flow is organized from a Solo device standpoint.

Basic concepts:

1. Each Solo device connected into a Chorus has its ID (order number), which is assigned dynamically upon initialization of the Chorus device from a communicating application. Normally enumeration starts with 0.
2. Each data chunk is a plain string terminated with "\n" character (ASCII=10) and having a predefined structure.
3. There are 3 types of data chunks:

• Requests
• Responses
• Pass-through data

4. Almost each Request produces a Response
5. Pass-through data is either a request to a different Solo device, or response which needs to pass through current device to reach the Bluetooth dongle and be transmitted to App.

Requests

There are 3 types of requests:

1. Device enumeration: (3 characters) "N" + <first_ID> + "\n". Example: "N0\n"
2. Command/Request: (4 characters) "R" + <device_ID> + <command> + "\n". Example: "R1T\n"
3. Calibration: (11 characters) "C" + <device_ID> + <time_long_HEX_value> + "\n". Example: "C00000010A\n"

In any "R" request: <device_ID> may be set to "*", which means the request is addressed to all devices (broadcast), and each should provide a response. Example: "R*A\n"

Note: for broadcast requests the order of responses from different devices is not defined. Example: "S1R1\nS0R1\nS2R1\n"

Responses

Response structure: "S" + <device_ID> + <response_type> + <data> + "\n" Each response type has its own predefined length depending on size of data to be transmitted.

Correspondence of Requests to Responses:

Description	Request	Response	Description	Example (request -> response)
Enumeration	-----	-----	-----	-----
Enumerate Devices	N	N	Number of Devices	N0\n -> N3\n (3 devices found)
Calibration	-----	-----	-----	-----
Set Calibration Value	C	i	Calibration State (half-byte, 1 = Calibrated, 0 = Not Calibrated)	C100000006\n -> S1i1\n
Commands	-----	-----	-----	-----
Start Race	R	R	Race Status (half-byte; 1 = On, 0 = Off)	R*R\n -> S0R1\nS1R1\n...
End Race	r	R	Race Status (half-byte; 1 = On, 0 = Off)	R*r\n -> S0R0\nS1R0\n...
Increase Min Lap Time	M	M	Minimal Lap Time (1 byte, in seconds)	R0M\n -> S0M0A\n
Decrease Min Lap Time	m	M	Minimal Lap Time (1 byte, in seconds)	R1m\n -> S1M0A\n
Next RF Band	B	B	Current Band (half-byte; 0 - 5)	R0B\n -> S0B5\n
Previous RF Band	b	B	Current Band (half-byte; 0 - 5)	R0b\n -> S0B4\n
Next Channel	C	C	Current Channel (half-byte; 0 - 7)	R0C\n -> S0C5\n
Previous Channel	c	C	Current Channel (half-byte; 0 - 7)	R0c\n -> S0C4\n
Increase Threshold	T	T	Current Threshold (2 bytes)	R0T\n -> S0T010A\n
Decrease Threshold	t	T	Current Threshold (2 bytes)	R0t\n -> S0T0109\n
Set/Clear Threshold	S	T	Current Threshold (2 bytes)	R0S\n -> S0T0000\n
Enable/Disable Sounds	D	D	Sound State (half-byte; 1 = On, 0 = Off)	R1D\n -> S1D0\n
Start Calibration	I		No Response	R*I\n ->
End Calibration	i	I	Calibration Time (4 bytes)	R*i\n -> S1I00002710\nS0I00002715\n...
RSSI Monitor On	V	V	RSSI Monitor State (half-byte; 1 = On, 0 = Off)	R0V\n -> S0V1\n
RSSI Monitor Off	v	V	RSSI Monitor State (half-byte; 1 = On, 0 = Off)	R0v\n -> S0V0\n
Skip/Enable First Lap	F	F	First Lap State (half-byte; 1 = Skip, 0 = Count)	R*F\n -> S0F1\nS1F0\n...
---	---	S	Current RSSI Value; sent each 100ms when RSSI Monitor is On (2 bytes)	-> S0S0111\n
---	---	L	Lap Time; last Lap Time is automatically sent in race mode when drone passes the gate; All Lap Times sent as a response to Bulk Device State (see below); Format: (1 byte: lap number + 4 bytes: lap time)	-> L010000025C\n
Bulk Device State	A	CRMTSLDBVF + X	All states corresponding to specified letters (see above) plus 'X' meaning the end of state transmission for each device	R0A\n -> S0C2\nS0R1\nS0M10\n...S0X1\n