04-Expansion_Pins_Testing

K5 Expansion Pins

image-20241009150239258

K5C Expansion Pins

image-20250515144550428

• Pins marked with * indicate default software configurations.

• UART0_RX/TX: Default debug UART.

• TWI refers to I2C (e.g., TWI1_SCK/SDA = I2C_CLK/SDA).

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UART

Check device nodes

$ ls dev/ttyS*  

• ttyS0 ↔ DEBUG_UART0

• ttyS2 ↔ UART2

• ttyS7 ↔ S_UART

Set baud rate

stty -F /dev/ttyS2 ispeed 115200 ospeed 115200 cs8  

Send data to UART

echo kickpi > /dev/ttyAS2  

Receive data

cat /dev/ttyAS2  

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GPIO

sys LED Control

LEDs registered as GPIO can be controlled via the brightness node.

High-level voltage: PB-3.3V / PC-1.8V

List registered LEDs

$ ls /sys/class/leds/  
    PC12  PC2  PC3  PC4  PC7  PH8  PL4  PL5  fan_en  spk_en  sysled  

Example: Control PH8 pin

console:/ # ls /sys/class/leds/PH8  
brightness device max_brightness power subsystem trigger uevent  

console:/ # cat /sys/class/leds/PH8/brightness  
255  

console:/ # echo 0 > /sys/class/leds/PH8/brightness  # Set low level  
console:/ # cat /sys/class/leds/PH8/brightness  
0  

console:/ # echo 1 > /sys/class/leds/PH8/brightness  # Set high level  
console:/ # cat /sys/class/leds/PH8/brightness  
1  

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sunxi GPIO Control

cd /sys/kernel/debug/sunxi_pinctrl  

# Check pin configuration  
echo PH8 > sunxi_pin  
cat sunxi_pin_configure  

# Configure pin as GPIO output  
echo 'PH8 1' > function  

# Verify configuration  
cat sunxi_pin_configure  

# Check pin level  
cat data  

# Set high level  
echo 'PH8 1' > data  

# Set low level  
echo 'PH8 0' > data  

# Note: For pins PL and beyond, switch pin device first  
echo pio > /sys/kernel/debug/sunxi_pinctrl/dev_name  
cat /sys/kernel/debug/sunxi_pinctrl/dev_name  

echo r_pio > /sys/kernel/debug/sunxi_pinctrl/dev_name  
cat /sys/kernel/debug/sunxi_pinctrl/dev_name