MSU204A MEMS Inertial Measurement Unit

 

 

 

Vibration suppression and attitude control of industrial equipment

Automatic control systems

Gimbal stabilization and control

 

 

MSU204A MEMS is a compact, high-precision 9-axis inertial measurement unit (IMU), designed for high-precision navigation, control and dynamic measurement of carriers. The MSU204A series inertial measurement module integrates MEMS gyroscopes, MEMS accelerometers and MEMS magnetometers within a single housing. Adopting highly reliable MEMS sensors, it can accurately measure angular rate, acceleration and magnetic field information of moving carriers under harsh environments, making it a general-purpose device for industrial applications.

 

 

Company is a high-tech enterprise with full closed-loop capabilities from fiber winding to FOGs, fiber/MEMS inertial products, IMU circuits, software, and test equipment. End-to-end process control improves quality and reduces costs. Operating under ISO9001, it ensures reliability and consistency.The MSU204A inertial measurement module adopts an aluminum alloy housing, which is lightweight with high structural strength and excellent anti-vibration & anti-shock performance.

 

 

Product Introduction

MSU204A MEMS is a compact, high-precision 9-axis inertial measurement unit (IMU), designed for high-precision navigation, control and dynamic measurement of carriers. The MSU204A series inertial measurement module integrates MEMS gyroscopes, MEMS accelerometers and MEMS magnetometers within a single housing. Adopting highly reliable MEMS sensors, it can accurately measure angular rate, acceleration and magnetic field information of moving carriers under harsh environments, making it a general-purpose device for industrial applications.

 

Key Features

• 3-axis digital gyroscope, measurement range ±500 °/s
• 3-axis digital accelerometer, measurement range ±16 g
• Digital barometric pressure sensor, range 300 mbar ~ 1100 mbar
• Full-temperature calibration and compensation from -40 ℃ to +80 ℃ (for gyroscopes and accelerometers)
• SPI serial communication compatible
• Built-in temperature sensor
• Compact size and lightweight
• Pin-to-pin compatible with ADIS16488A

 

Application Fields

• Vibration suppression and attitude control of industrial equipment
• Automatic control systems
• Robot control
• Gimbal stabilization and control
• Instruments and meters

 

 

Table 1 Performance Parameters of MSU204A Inertial Measurement Module

Parameter Group	Parameter	Test Condition	Min.	Typical	Max.	Unit
Gyroscope	Measurement Range		-500		+500	°/s
	Full-temperature Bias			100	300	°/h
	Bias Stability	10s smoothing		5		°/h
	Bias Instability	Allan variance		1		°/h
	Bias Repeatability	Constant temperature		1.5	5	°/h
	Angular Random Walk			0.1		°/√h
	Scale Factor Non-linearity			25	100	ppm
	Cross-coupling Error				0.001	Rad
	Bandwidth		200			Hz
Accelerometer	Measurement Range		-16		+16	g
	Full-temperature Bias			1	3	mg
	Bias Stability	10s smoothing		0.03	0.1	mg
	Bias Instability	Allan variance		0.01	0.03	mg
	Bias Repeatability	Constant temperature		0.03	0.1	mg
	Velocity Random Walk			0.01	0.03	m/s/√h
	Scale Factor Non-linearity	±1 g input		100	200	ppm
	Cross-coupling Error				0.001	Rad
	Bandwidth		200			Hz
Magnetometer	Measurement Range		-8		+8	Gs
	Resolution			200		μGs
	Noise Density			50		μGs
	Bandwidth			200		Hz
Barometer	Measurement Range		300		1100	mbar
	Total Error			4.5		mbar
	Absolute Error			1.5		mbar
	Non-linearity			0.1		%FS
	Resolution			0.1		mbar
Communication Interface	SPI Clock Frequency				10	MHz
	UART Baud Rate		9.6	460.8	921.6	kbps
Electrical Characteristics	Operating Voltage		3.0	3.3	3.6	V
	Power Consumption			0.5		W
	Ripple (Peak-to-Peak)				100	mV
Startup Time	-			2		s
Mechanical Characteristics	Dimension		47.0 × 44.0 × 14.0			mm
	Weight				50	g
Operating Environment	Operating Temperature		-40		80	℃
	Storage Temperature		-55		85	℃
	Vibration Resistance		10-2000Hz, 6.06g
	Shock Resistance		30g, 11ms
	Overload Tolerance	Half-sine pulse	1000 g
Reliability	MTBF (Mean Time Between Failures)			20000		h
	Continuous Operating Duration			120		h
Note: Typical values represent 1σ statistical results of multiple sample tests.

 

Mechanical & Electrical Specifications

Mechanical Characteristics

The MSU204A inertial measurement module adopts an aluminum alloy housing, which is lightweight with high structural strength and excellent anti-vibration & anti-shock performance. The outline dimension of the unit is shown in Figure 1, and the unit is fixed by four M2 screws.

Figure 1 Module Outline Dimension Drawing

 

Product Marking & Coordinate Definition

During installation, the carrier coordinate system of the module must maintain a fixed relative relationship with the carrier coordinate system of the target equipment. The carrier coordinate system definition of MSU204A MEMS inertial measurement module is shown below.

Figure 2 Inertial Sensor Axis Reference Diagram

 

Interface Characteristics

The MSU204A inertial measurement module uses a customized double-row pin connector FTMH-112-02-H-DH for external signal output (mating plug: Samtec CLM-112-02 or equivalent alternative), which supplies power and realizes external communication. The pin assignment of the connector is defined in Table 2.

Table 2 Connector Pin Definition of MSU204A Inertial Measurement Module

Pin Numbers	Name	Type	Description
10, 11, 12	VDD	Power Supply	-
13, 14, 15	GND	Power Ground	-
7	DIO1	Input / Output	Configurable general-purpose IO
9	DIO2	Input / Output
1	DIO3	Input / Output
2	DIO4	Input / Output
3	SPI-CLK	Input	SPI master-slave mode fixed, non-configurable
4	SPI-MISO	Output
5	SPI-MOSI	Input
6	SPI-CS	Input
16	UART-0-TXD	Output	UART0, debug-only
17	UART-0-RXD	Input
8	RST	Input	Hardware reset
23	VDD RTC	Power Supply	Unused
22, 24, 18, 19, 20, 21	NC	Reserved	No internal connection

Figure 3 External Connector Pin Label Diagram

 

When the supply voltage drops below the device operating threshold, the power-off hold time tOFF before re-powering shall not be less than 3 seconds. Insufficient power-off interval may cause abnormal startup, latch-up or initialization failure of the device.

 

External Communication

The MSU204A is a self-contained sensor system. It automatically starts up after valid power supply, completes initialization, then starts sampling, processing and writing calibrated sensor data to output registers, which can be accessed via SPI interface. The SPI bus is usually connected to a compatible port of an embedded processor. Four SPI signals support synchronous serial data transmission. Under factory default configuration, DIO4 serves as data ready flag; this pin will pull high when new valid data exists in output registers.

Figure 4 Electrical Connection Schematic

 

Table 3 General SPI Host Configuration

Host Parameter	Description
Host Mode	MSU204A operates as SPI slave device
SCLK Frequency	Max serial clock ≤ 10 MHz
SPI Mode	Mode 3 (CPOL=1, CPHA=1)
Bit Order	MSB-first transmission
Data Width	16-bit shift register frame

The SPI interface supports full-duplex communication: the external processor can write DIN data while reading DOUT data if the previous transaction is a read request (see Figure 4). Figure 4 provides bit encoding examples for DIN and DOUT signals.

Figure 5 SPI Communication Bit Sequence

 

The MSU204A automatically activates Page 0 for data register access after power-up. After accessing other register pages, write 0x00 to the PAGE_ID register (DIN=0x8000) to switch back to Page 0.

Reading a single register requires two 16-bit SPI cycles:

The first cycle sends register address request with bit allocation defined in Figure 3

The second cycle returns target register data via DOUT

The first bit of DIN command is 0, followed by high/low bytes of register address. The last 8 bits are dummy bits, but a complete 16 SCLK cycle is required for SPI reception of the request.

Figure 5 illustrates two consecutive register read operations: DIN=0x1A00 requests Z_GYRO_OUT register data, then DIN=0x1800 requests Z_GYRO_LOW register data.

Figure 6 SPI Read Transaction Example

 

Table 4 User Register Memory Map (N/A = Not Applicable)

R/W	Page ID	Address	Default Value	Register Description
R/W	0x00	0x00	0x00	Page ID Select Register
R	0x00	0x0E	N/A	Temperature Output
R	0x00	0x10	N/A	X-axis Gyro Output (Low Word)
R	0x00	0x12	N/A	X-axis Gyro Output (High Word)
R	0x00	0x14	N/A	Y-axis Gyro Output (Low Word)
R	0x00	0x16	N/A	Y-axis Gyro Output (High Word)
R	0x00	0x18	N/A	Z-axis Gyro Output (Low Word)
R	0x00	0x1A	N/A	Z-axis Gyro Output (High Word)
R	0x00	0x1C	N/A	X-axis Accelerometer Output (Low Word)
R	0x00	0x1E	N/A	X-axis Accelerometer Output (High Word)
R	0x00	0x20	N/A	Y-axis Accelerometer Output (Low Word)
R	0x00	0x22	N/A	Y-axis Accelerometer Output (High Word)
R	0x00	0x24	N/A	Z-axis Accelerometer Output (Low Word)
R	0x00	0x26	N/A	Z-axis Accelerometer Output (High Word)
R	0x00	0x28	N/A	X-axis Magnetometer Output (High Word)
R	0x00	0x2A	N/A	Y-axis Magnetometer Output (High Word)
R	0x00	0x2C	N/A	Z-axis Magnetometer Output (High Word)
R	0x00	0x2E	N/A	Barometric Pressure Output (Low Word)
R	0x00	0x30	N/A	Barometric Pressure Output (High Word)
R	0x00	0x7E	0x4068	Part ID Output (Compatible with ADIS16488)

 

Inertial Sensor Data Format

The output registers of gyroscope, accelerometer and barometer adopt 32-bit binary format, split into two separate 16-bit registers. Figure 7 shows how register pairs compose inertial measurement data. For example, X_GYRO_OUT stores high 16 bits, X_GYRO_LOW stores low 16 bits. In most scenarios, only high 16-bit register data is sufficient to meet resolution requirements.

Figure 7 Gyroscope Output Format Example (DEC_RATE > 0)

 

Temperature Calculation Formulas

Current Temperature = 25 + TEMP_OUT × 0.00565

Gyroscope Calculation Formula

X-axis Gyroscope	X_GYRO_OUT	X_GYRO_LOW
	1LSB = 0.02 °/s	The weight of the most significant bit (MSB) is 0.01 °/s, and the weight of subsequent bits decreases by half sequentially.
	0. 02 * X_GYRO_OUT	0.01*MSB+0.005*...

 

Accelerometer Calculation Formula

X-axis Accelerometer	X_ACCL_OUT	X_ACCL_LOW
	1LSB = 0.8mg	The weight of the most significant bit (MSB) is 0.4 mg, and the weight of subsequent bits decreases by half sequentially.
	0.8 * X_ACCL_OUT	0.4 * MSB + 0.2*...

 

Magnetic Field Calculation Formula:

X-axis Magnetometer	X_MAGN_OUT
	1LSB = 0.1mGauss
	0.1 * X_MAGN_OUT

 

Barometric Pressure Calculation Formula

Barometric Pressure (Bar)	BAROM_OUT	BAROM_LOW
	1LSB = 40ubar	The weight of the most significant bit (MSB) is 20 μbar, and the weight of subsequent bits decreases by half sequentially.
	40 * BAROM_OUT	20 * MSB + 10*....

 

Product Operation Precautions

• Confirm the electrical pin definition strictly; follow the pinout arrangement during wiring to avoid misconnection.
• This product is precision measuring equipment. Avoid impact, collision or mechanical overload exceeding the rated limit during handling.
• Mounting flatness significantly affects angular rate measurement. Ensure the mounting surface has high flatness to eliminate installation-induced error.
• Fix the module firmly and reliably to prevent measurement drift caused by loose assembly.
• Take anti-static protection measures during installation and operation; wearing an anti-static wristband is recommended.
• Operate the device strictly in accordance with this manual and verify the external environment meets operating requirements. Do not disassemble the housing or modify internal hardware if any fault occurs; contact our technical support team for troubleshooting.

 

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