phaten-audio/en/docs/dev_doc/protocols/XMOS_EQ_UART_Protocol.md

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XMOS EQ UART Control Protocol and Command Set	UART serial communication protocol specification for EQ parameter configuration and control, covering frame format, command set, and field descriptions, applicable to XU316 and related products.	EQ, UART, Serial Protocol, Communication Protocol, Command Set, XU316, Zero-Code Firmware, Phaten Audio

XMOS EQ UART Control Protocol and Command Set

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1. Protocol Foundation Specification

1.1 Underlying Communication Protocol

Based on UART (Universal Asynchronous Receiver/Transmitter) protocol.

Parameter	Value
Baud Rate	115200 bps
Data Bits	8
Parity	None
Stop Bits	1
Flow Control	None

1.2 Frame Format and Data Transmission

General Frame Format All commands and responses follow this frame format:

Field	Byte Count	Description
Frame Header	2	Fixed as 0x55 0xAA
Version	1	Protocol version number (typically 0x00)
Command	1	Indicates frame function (e.g., 0x30)
Data Length	1	Length N of subsequent data
Data	N	Specific data content
Checksum	1	Sum of all bytes from frame header, modulo 256 (Sum % 256)

Data Transmission Notes

• Byte Order: All multi-byte data is transmitted in Little Endian mode (Note: Different from XU316 standard protocol's big endian, please refer to this protocol).
• Floating Point: Follows IEEE 754 float format.

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2. Protocol Command Set

2.1 Command Classification Overview

Command	Command Description	Direction	Function
0x30	SET_EQ_MODE	Host→Device	Switch current EQ mode
0x31	GET_EQ_MODE	Host→Device	Get current EQ mode information (mode number, gain, name)
0x32	SET_MODE_GAIN_AND_NAME	Host→Device	Set overall gain and name for specified mode
0x33	SET_EQ_PARAMS	Host→Device	Send single filter parameters (Freq, Q, Gain, etc.)
0x34	GET_EQ_PARAMS	Host→Device	Read single filter parameters
0x35	RESET_EQ_PARAMS	Host→Device	Reset EQ parameters (restore presets)

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3. Basic Function Command Details

3.1 Switch EQ Mode (0x30)

Host Sends

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x30	Command code
Length	1	0x01	Data length
Data	1	Mode	Mode value 0-5: Preset modes 6-8: User modes 9: Bypass
Checksum	1	Sum	Checksum

Device Processing

• Directly sets the currently running EQ mode.
• Does not involve parameter transmission or calculation.

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3.2 Get Current EQ Mode Information (0x31)

Host Sends

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x31	Command code
Length	1	0x00	No data
Checksum	1	Sum	Checksum

Device Returns (Response)

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x31	Command code
Length	1	0x15	Data length (21 bytes)
Data	1	Mode	Current mode value
	4	Gain	Overall gain (int32, little endian, range 0~-50dB)
	16	Name	Mode name (UTF-8 string)
Checksum	1	Sum	Checksum

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3.3 Set Mode Overall Gain and Name (0x32)

Host Sends

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x32	Command code
Length	1	0x15	Data length (21 bytes)
Data	1	Mode	Target mode value (0-9)
	4	Gain	Overall gain (int32, little endian)
	16	Name	Mode name (UTF-8 string)
Checksum	1	Sum	Checksum

Device Processing

• Sets gain and name for specified mode, automatically applied to all sample rates.

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3.4 Send EQ Parameters (0x33)

Host Sends

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x33	Command code
Length	1	0x15	Data length (21 bytes)
Data	1	Mode	Mode value (0-9)
	1	Band	Filter index (0-7)
	1	Type	Filter type (see table below)
	4	Freq	Center frequency Hz (float, little endian)
	4	Q	Q value (float, little endian)
	4	BW	Bandwidth Hz (float, little endian)
	4	Gain	Gain dB (float, little endian)
Checksum	1	Sum	Checksum

Filter Type Codes

Code	Type	Code	Type
0x00	Bypass	0x06	Band Reject
0x01	All Pass	0x07	Notch
0x02	Peak	0x08	Constant Q
0x03	Low Pass	0x09	Low Shelf
0x04	High Pass	0x0A	High Shelf
0x05	Band Pass

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3.5 Read EQ Parameters (0x34)

Host Sends

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x34	Command code
Length	1	0x02	Data length
Data	1	Mode	Mode value (0-9)
	1	Band	Filter index (0-7)
Checksum	1	Sum	Checksum

Device Returns (Response)

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x34	Command code
Length	1	0x15	Data length (21 bytes)
Data	1	Mode	Mode value
	1	Band	Filter index
	1	Type	Filter type
	4	Freq	Center frequency (float, little endian)
	4	Q	Q value (float, little endian)
	4	BW	Bandwidth (float, little endian)
	4	Gain	Gain (float, little endian)
Checksum	1	Sum	Checksum

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3.6 Reset EQ Parameters (0x35)

Host Sends

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x35	Command code
Length	1	0x01	Data length
Data	1	Mode	Mode number (0-9) 0xFF indicates reset all modes
Checksum	1	Sum	Checksum

Device Returns (Response)

Byte Position	Length	Content	Description
Frame Header	2	0x55 0xAA	Fixed frame header
Version	1	0x00	Protocol version
Command	1	0x35	Command code
Length	1	0x01	Data length
Data	1	Status	Status code (0x00=success, 0x01=failure)
Checksum	1	Sum	Checksum

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