03 - MPU6050 Gyroscope Application

This chapter describes the MPU6050 six-axis motion sensor application example on the Pico-G1 expansion board — mpu6050_display. It demonstrates how to read acceleration, angular velocity, and temperature data from the MPU6050 sensor over the I2C interface and display them in real time on a TFT screen. It is a practical example for learning I2C sensor communication and motion data processing.

The application source code lives in the SDK directory source/app/03_mpu6050_display/, providing a complete implementation of I2C sensor reading and data processing.

1 Application Overview

1.1 Features

I2C sensor communication: demonstrates reading MPU6050 sensor data over the I2C interface
Six-axis data acquisition: reads three-axis acceleration and three-axis angular velocity simultaneously
Temperature monitoring: reads the sensor's internal temperature data
Real-time display: shows motion data on a TFT screen
INT pin monitoring: supports MPU6050 data-ready interrupt detection
Multi-chip compatibility: supports MPU6050/MPU6500/MPU9250 and similar chips

1.2 Technical Specifications

Parameter	Value
`I2C interface`	I2C3 (/dev/i2c-3)
`Slave address`	0x68 (AD0 grounded)
`Accelerometer range`	±2g (16384 LSB/g)
`Gyroscope range`	±250°/s (131 LSB/°/s)
`Temperature accuracy`	±1°C
`Refresh interval`	150ms (configurable)
`TFT display`	ST7789 240×240

1.3 Test Case List

index	Name	Test command	Expected result (success)	Possible causes of failure
1	Basic acquisition	`./mpu6050_display`	Screen shows acceleration, angular velocity, and temperature data	I2C connection failure, damaged sensor
2	Static test	Keep the module still	Z-axis acceleration is about ±1g	Wrong sensor orientation
3	Tilt test	Tilt the module	Acceleration on the corresponding axis changes	Data parsing error
4	Temperature test	Touch the sensor	The temperature value rises	Sensor failure

1.4 Directory Structure

source/app/03_mpu6050_display/
├── Makefile              # Build script
├── main.c                # Main program
├── mpu6050.c             # MPU6050 driver implementation
├── mpu6050.h             # MPU6050 driver header
├── i2c_hal.c             # I2C HAL layer implementation
├── i2c_hal.h             # I2C HAL layer header
├── gpio_hal.c            # GPIO HAL layer implementation
├── gpio_hal.h            # GPIO HAL layer header
├── spi_hal.c             # SPI HAL layer implementation
├── spi_hal.h             # SPI HAL layer header
├── st7789.c              # ST7789 driver implementation
├── st7789.h              # ST7789 driver header
├── font8x16.h            # 8×16 ASCII bitmap font
└── README.md             # Documentation

2 Hardware Connection

2.1 Pin Definition

Signal	On-board GPIO	Controller / node	Description
SCL	GPIO4_1	I2C3 → `/dev/i2c-3`	Bus shared with the OLED (0x3C)
SDA	GPIO4_2	I2C3 → `/dev/i2c-3`	Bus shared with the OLED
INT	GPIO0_0	`/dev/gpiochip0` line0	Data-ready indication (optional)
AD0	Tied to GND	—	Slave address = 0x68
Display	SPI2	`/dev/spidev2.0`	ST7789 240×240

2.2 Hardware Circuit

Standard MPU6050 wiring:

     Pico-G1                   MPU6050 Module
  ┌───────────┐              ┌──────────────┐
  │           │              │              │
  │ GPIO4_1 ──┼────── SCL ──┤ SCL          │
  │           │              │              │
  │ GPIO4_2 ──┼────── SDA ──┤ SDA          │
  │           │              │              │
  │ GPIO0_0 ──┼────── INT ──┤ INT (optional) │
  │           │              │              │
  │    3.3V ──┼─────────────┤ VCC          │
  │           │              │              │
  │     GND ──┼─────────────┤ GND          │
  │           │              │    AD0 ─── GND│
  └───────────┘              └──────────────┘

Address selection

AD0 tied to GND: I2C address = 0x68 (default)
AD0 tied to VCC: I2C address = 0x69
On most modules AD0 is already grounded; no extra wiring is needed

2.3 Pin Multiplexing

Pin multiplexing that needs to be configured:

pad	Physical address	Value	Description
I2C3_SCL (GPIO4_1)	`0x100C0010`	`0x1002`	func2 = I2C3_SCL
I2C3_SDA (GPIO4_2)	`0x100C0014`	`0x1002`	func2 = I2C3_SDA
INT (GPIO0_0)	`0x112C0000`	`0x1000`	func0 (GPIO) + input enable

3 Build and Deployment

3.1 Prerequisites

Before building this application, make sure the following preparations are complete:

SDK environment ready: set up the cross-compilation toolchain and SDK by following Development Environment Setup
MPU6050 module connected: the MPU6050 is correctly wired to the I2C3 interface

3.2 Building the Application

# Set the toolchain path
export PATH=$PATH:<SDK>/tools/linux/toolchains/arm-gcc12.2.0-linux-uclibceabi/bin

# Enter the example directory
cd <SDK>/source/app/03_mpu6050_display

# Build
make

# Clean
make clean

3.3 Deploying to the Board

# Transfer to the development board with SCP
scp mpu6050_display root@<board-IP>:/usr/bin/

# Or download via TFTP
tftp -g -r mpu6050_display <board-IP>

3.4 Running the Application

# Add execute permission
chmod +x /usr/bin/mpu6050_display

# Run the MPU6050 display example
/usr/bin/mpu6050_display

3.5 Expected Output

Console output

/mnt # ./mpu6050_display
[mpu] pad 复用：I2C3(4_1/4_2)->func2，GPIO0_0->func0
[mpu] pad 0x100C0010 -> 0x00001002
[mpu] pad 0x100C0014 -> 0x00001002
[mpu] pad 0x112C0000 -> 0x00001000
[mpu] 初始化 SPI 屏（/dev/spidev2.0）...
[spi] pad 0x100C0028 -> 0x00001004
[spi] pad 0x100C002C -> 0x00001004
[spi] pad 0x100C0030 -> 0x00001000
[spi] pad 0x100C0020 -> 0x00001005
[spi] pad 0x100C001C -> 0x00001005
[spi] opening /dev/spidev2.0 ...
[spi] spidev opened, fd=3
[spi] spidev mode/bits/speed set (MODE3/8b/24MHz)
[spi] chardev request DC  @ /dev/gpiochip4 line 5 ...
[spi] chardev request RES @ /dev/gpiochip4 line 4 ...
[spi] chardev request CS  @ /dev/gpiochip5 line 1 ...
[spi] chardev-verify: DC=0(expect0) RES=1(expect1) CS=1(expect1)  ==> OK(chardev 真驱动了引脚)
[spi] spi_hal_init done
[tft] init: SLPOUT
[tft] init: SLPOUT +120ms ok
[tft] init: config cmds ok
[tft] init: DISPON
[tft] init: DISPON ok
[tft] init: clear-flush start
[tft] flush #1 start
[tft] flush #1 done
[tft] init: clear-flush done
[mpu] SPI 屏就绪。
[mpu] 初始化 MPU6050（/dev/i2c-3 addr 0x68）...
[mpu] WHO_AM_I = 0x70
[mpu] 识别为 MPU6500
[mpu] 初始化成功 @ /dev/i2c-3 addr 0x68 (±2g / ±250dps, 100Hz)
[mpu] 采集显示中，每 150ms 刷新，Ctrl+C 退出。

TFT screen display

MPU6050 display effect

4 Troubleshooting

Problem	Possible cause	Solution
WHO_AM_I read failure	I2C connection failure, wrong address	Check wiring, confirm the address configuration
WHO_AM_I = 0xFF	No I2C response	Check SCL/SDA wiring, confirm the power supply
WHO_AM_I is not 0x68	MPU6500/MPU9250 chip	The driver already supports 0x70/0x71
Data not updating	Sensor not woken up	Check the PWR_MGMT_1 register