00 - Pico Expansion Board Peripheral Examples Overview

This chapter presents application examples for the various peripheral features of the Pico-G1 expansion board. These examples demonstrate how to use the hardware modules on the expansion board, including display devices, sensors, actuators, and other common peripherals. Each example provides complete hardware wiring instructions, software implementation code, and detailed deployment and running guides, helping developers quickly master peripheral programming skills.

1 Expansion Board Overview

The Pico-G1 expansion board provides the development board with a rich set of peripheral interfaces, including but not limited to:

Display devices: OLED screen (I2C), TFT screen (SPI)
Sensors: MPU6050 gyroscope, MQ gas sensor, SHT20 temperature/humidity sensor, ultrasonic ranging module, SPO2 blood-oxygen sensor
Actuators: buzzer, motor, servo
Others: GPS module, ADC acquisition

These peripherals cover the most commonly used functional modules in embedded system development, making them ideal for learning embedded programming and IoT application development.

2 Application Example List

No.	Application	Description	Bus	Link
1	OLED display	SSD1306 128×64 OLED text display	I2C	Details
2	TFT display	ST7789 240×240 TFT color display	SPI	Details
3	MPU6050 gyroscope	Six-axis motion sensor data acquisition and display	I2C	Details
4	ADC acquisition	Analog signal acquisition and display	ADC	Details
5	Buzzer	Passive buzzer frequency control	GPIO	Details
6	MQ gas sensor	Air quality monitoring	ADC	Details
7	GPS positioning	GPS data parsing and location display	UART	Details
8	SHT20 temperature/humidity	Ambient temperature and humidity monitoring	I2C	Details
9	Ultrasonic ranging	Distance measurement with RGB parking-sensor display	GPIO	Details
10	SPO2 blood oxygen	Heart rate and blood-oxygen monitoring	I2C	Details
11	Motor control	DC motor PWM speed control	GPIO	Details
12	Servo control	Precise servo angle control	GPIO	Details

3 Hardware Platform Features

3.1 Main Chip

Chip model: GK7602V11A (internal SDK codename xm7206v11a, architecture xmorca)
CPU architecture: ARM Cortex-A7
Operating system: Linux (supports standard device nodes such as /dev/gpiochip, /dev/i2c-*, /dev/spidev.*)

3.2 GPIO Features

Supports the standard GPIO character device interface
Supports direct access to IOCFG registers via /dev/mem for pin-mux configuration
Provides digital control for the buzzer, motor, servo, etc.

3.3 Communication Interfaces

I2C: supports I2C0, I2C2, I2C3 (corresponding to /dev/i2c-0, /dev/i2c-2, /dev/i2c-3)
SPI: supports multiple SPI controllers (corresponding to /dev/spidev.*.*)
UART: supports multiple serial controllers (corresponding to /dev/ttyS*)
ADC: supports analog signal acquisition (12-bit resolution)

4 Development Environment Preparation

4.1 Prerequisites

SDK environment: set up the cross-compilation environment as described in Development Environment Setup
Hardware connection: make sure the expansion board is properly connected to the Pico-G1 development board
Serial connection: access the on-board Linux system via serial or SSH

4.2 Toolchain Setup

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

# Verify the toolchain
arm-linux-gcc --version

4.3 Common Build Workflow

All examples share a unified Makefile structure:

# Enter the example directory
cd <SDK>/source/app/<example-name>

# Build
make

# Clean
make clean

# Deploy to the board
scp <executable> root@<board-IP>:/usr/bin/

# Run
ssh root@<board-IP} '/usr/bin/<executable>'

5 Code Architecture Design

5.1 HAL Layer Encapsulation

Each example adopts the hardware abstraction layer (HAL) design pattern, encapsulating low-level hardware operations in separate HAL modules:

gpio_hal.c/h: GPIO character device operation encapsulation
i2c_hal.c/h: I2C device read/write encapsulation
spi_hal.c/h: SPI device read/write encapsulation
uart_hal.c/h: UART serial communication encapsulation

This design keeps the application code clean and makes it easy to port to other platforms.

5.2 Driver Layer Implementation

For specific peripheral chips, independent driver modules are provided:

ssd1306.c/h: OLED screen driver
st7789.c/h: TFT screen driver
mpu6050.c/h: MPU6050 sensor driver
sht20.c/h: SHT20 temperature/humidity sensor driver
etc...

5.3 Application Layer Code

The main.c file of each example demonstrates the complete application flow, including:

Hardware initialization
Pin-mux configuration (if needed)
Peripheral initialization
Main loop processing
Resource cleanup

6 Recommended Learning Path

6.1 Beginner Path

It is recommended to learn in the following order, from simple to complex:

Buzzer → learn basic GPIO control
OLED display → learn I2C communication and display drivers
MPU6050 → learn I2C sensor data reading
TFT display → learn high-speed SPI communication

6.2 Advanced Path

Once you have mastered the basics, you can move on to more complex applications:

GPS positioning → learn UART serial communication and NMEA protocol parsing
Ultrasonic ranging → learn GPIO timing control
Motor control → learn PWM output and actuator control
Servo control → learn precise PWM control
Integrated applications → combine multiple sensors and actuators into a complete system

7 Debugging Tips

7.1 Hardware Debugging

Device node check: ls -l /dev/i2c-*, ls -l /dev/spidev.*.*, etc.
Pin-mux verification: check the pin configuration via boot logs or /dev/mem tools
I2C device probing: use i2cdetect or on-board tools to probe slave device addresses

7.2 Software Debugging

Log output: add printf debug messages
Return value check: check the return value of every system call
Step-by-step testing: test the hardware connection first, then the driver functions, and finally the application logic

8 FAQ

Problem	Possible cause	Solution
Device node does not exist	Kernel driver not loaded or device tree misconfigured	Check the kernel config and device tree DTS
I2C/SPI communication failure	Pin-mux error or wiring problem	Verify the hardware connection with `i2cdetect` and similar tools
Program unresponsive	Deadlock or infinite loop	Add debug messages and check the loop logic
Build error	Wrong toolchain path or missing headers	Reset PATH and check SDK integrity

9 References

9.2 Code Location

All example code lives in the SDK's source/app/ directory:

<SDK>/source/app/
├── 01_oled_display/     # OLED display
├── 02_TFT_display/      # TFT display
├── 03_mpu6050_display/  # MPU6050 gyroscope
├── 04_adc_display/      # ADC acquisition
├── 05_buzzer/           # Buzzer
├── 06_MQ_Sensor/        # MQ gas sensor
├── 07_gps_display/      # GPS positioning
├── 08_sht20_display/    # SHT20 temperature/humidity
├── 09_sonic_display/    # Ultrasonic ranging
├── 10_spo2_sensor/      # SPO2 blood oxygen
├── 11_motor/            # Motor control
└── 12_servo_ctrl/       # Servo control

10 Next Steps

Pick an example that interests you and start learning! We recommend starting with the buzzer or OLED display — these examples are relatively simple and will help you get familiar with the whole development workflow.

Tip: each example comes with a complete README covering hardware wiring, build & deployment, and run parameters in detail. When you hit a problem, first check the README.md in the corresponding directory.