Pinout

The development board comes with on-board GPIO header that can be used to connect external devices (temperature sensors, humidity sensors, etc.), communicate with other circuit boards or modules (I2C, SPI, UART, etc.), and support custom GPIO functionality.

K2B Pinout

K2B has a 20Pin GPIO header.

Note

1. Functions marked with * or in red font are the default software configurations. To configure them for other functions, please modify pin mux in source code.
2. DEBUG_UART0_RX / TX are configured by default for serial debugging and are not recommended for use as ordinary serial ports or for other functions.
3. TWI means I2C: TWI1_SCK / TWI1_SDA are equivalent to I2C_CLK / I2C_SDA.

K2C Pinout

K2C has a 20Pin GPIO header.

Note

1. Functions marked with * in the image are the default software configurations. To configure them for other functions, please modify pin mux in source code.
2. DEBUG_UART0_RX / TX are configured by default for serial debugging and are not recommended for use as ordinary serial ports or for other functions.
3. TWI means I2C: TWI1_SCK/TWI1_SDA are equivalent to I2C_CLK/I2C_SDA.

GPIO

WiringKP Installation

1. Use the command to check if the WiringKP tool is installed in the system.

which gpio

2. (Optional) If WiringKP is not installed in the system, download the wiringKP archive from the cloud disk, extract it, and place the executable and library files into the /usr/bin and /usr/lib directories, respectively.

WiringKP Operations

Tip

During the demonstration, the K2B development board is used as an example.

GPIO/PWM Command Usage Guide

gpio readall           // Get the status of all pins
gpio read <wPi>        // Read pin level
gpio mode <wPi> <mode> // Set pin working mode (current version supports setting out/int/up/down/pwm modes)
gpio write <wPi> <val> // Set pin output level

// PWM-related commands
gpio pwmr <wPi> <val>    // Set ARR
gpio pwm <wPi> <val>     // Set CCR
gpio pwmc <wPi> <val>    // Set prescaler coefficient
gpio pwmTone <wPi> <val> // Set frequency

Set PH5 to Output Mode, Output High Level

The PC pins output 1.8V, and the PH pins output 3.3V. After configuring the pins, you can use a multimeter to measure that the PH5 pin is at a high level.

kickpi@kickpi:~$ gpio mode 0 out
kickpi@kickpi:~$ gpio read 0
0
kickpi@kickpi:~$ gpio write 0 1
kickpi@kickpi:~$ gpio read 0
1
kickpi@kickpi:~$

Set PH5 to Input Mode

kickpi@kickpi:~$ gpio mode 0 in
kickpi@kickpi:~$ gpio mode 0 down
kickpi@kickpi:~$ gpio read 0
0
kickpi@kickpi:~$ // Short pins 3 and 4
kickpi@kickpi:~$ gpio read 0
1
kickpi@kickpi:~$

Set PH2 to PWM Mode

// By default, outputs a square wave with a frequency of 23475Hz and a 50% duty cycle
root@kickpi:~# gpio mode 3 pwm 

Adjust Duty Cycle

Note

PWM Duty Cycle = CCR/ARR
CCR range: 0~65535, default 512
ARR range: 1~65536, default 1024

// Set ARR to 2048, duty cycle = 512/2048 = 25%
gpio pwmr 3 2048

// Set CCR to 1024, duty cycle = 1024/2048 = 50%
gpio pwm 3 1024 

Adjust Frequency

// Default output frequency is 23475Hz
gpio mode 3 pwm 
// Set prescaler coefficient to 5, output frequency = 23475/5 = 4695Hz, actual frequency is 4688Hz, error is negligible
gpio pwmc 3 5   

gpio_para

gpio_para is located in the system directory /sys/class/gpio_sw and is the control driver for Allwinner GPIO, enabling simple high/low level control.

echo 1 > /sys/class/gpio_sw/PC12/data 
echo 0 > /sys/class/gpio_sw/PC12/data 

SPI

Tip

Short MISO and MOSI

spidev_test -D /dev/spidev1.0 -C -v -L -p "hello"

Serial Port

Tool Preparation

• Hardware: USB to TTL cable

Note

Red: VCC (no need to connect); Green: TX; White: RX; Black: GND

TTL Ordinary Serial Port

Connect using a serial port tool.

Serial Port Settings

ttyAS5 is serial port 5, corresponding to pins PH2 and PH3, with a baud rate of 115200:

stty -F /dev/ttyAS5 ispeed 115200 ospeed 115200 cs8

Send data to the serial port:

echo kickpi > /dev/ttyAS5  

Receive data:

cat /dev/ttyAS5