04-Expansion_Pins_Testing

GPIO

WiringKP Tool Usage

Check whether the system has WiringKP tools

which gpio

If not, download and copy it from the network disk to the board system

Tool download path: h618_data\3-SoftwareData\GPIO_tools

Extract wiringKP.tar.gz on the board. Place executables and libraries into /usr/bin and /usr/lib.

Example Usage

gpio readall // Get all pin status

gpio read <wPi>        // Read pin level
gpio mode <wPi> <mode> // Set pin mode (supports out/in/up/down/pwm)
gpio write <wPi> <val> // Set pin output level

pwm related command
gpio pwmr <wPi> <val>    //Setting ARR
gpio pwm <wPi> <val>     //Setting CCR
gpio pwmc <wPi> <val>    //Setting Frequency Dividing Coefficient
gpio pwmTone <wPi> <val> //Setting Frequency

**Set PH5 to output mode and output high level **

(Note: PC pins output 1.8V, PH pins output 3.3V):

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

Use a multimeter to verify PH5 is high. Set PH5 to input mode with pull-down

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

Set PH2 to PWM mode

root@kickpi:~# gpio mode 3 pwm #Default output frequency 23475Hz Square wave with duty cycle 50%

Adjust duty cycle

PWM duty cycle = CCR/ARR

CCR range: 0~65535 (default 512)

ARR range: 1~65536 (default 1024)

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

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

Adjust frequency

gpio mode 3 pwm //The default output frequency is 23475Hz
//Set the frequency division coefficient to 5, then the output frequency is 23475/5=4695Hz, the actual frequency is 4688Hz, the error can be ignored
gpio pwmc 3 5

gpio pwmTone 3 20000 //Directly set the frequency to 20000Hz

sys GPIO Control

Step 1: Release GPIO via /sys/class/gpio Ensure the target GPIO is in UNCLAIMED state:

cat /sys/kernel/debug/pinctrl/300b000.pinctrl/pinmux-pins

If pins are claimed (e.g., PH2/PH3 used as UART5), modify the device tree to disable default functions:

Edit device tree files:

vim longan/device/config/chips/h618/configs/p2/linux-5.4/board-*.dts  // Android
vim source/kernel/linux-5.4-h618/arch/arm64/boot/dts/sunxi/sun50iw9-kickpi-k2b.dts // Linux

Step 2: Rebuild and flash the firmware. Step 3: Confirm GPIO is unclaimed:

cat /sys/kernel/debug/pinctrl/300b000.pinctrl/pinmux-pins | grep PH

Step 4: Export and control GPIO (e.g., PH2=226, PH3=227):

Set direction:

echo in > /sys/class/gpio/gpio226/direction
echo out > /sys/class/gpio/gpio226/direction

Read/write value:

cat /sys/class/gpio/gpio226/value      // Read
echo 1 > /sys/class/gpio/gpio226/value // Set high
echo 0 > /sys/class/gpio/gpio226/value // Set low

Example Configurations

GPIO Output Default GPIO outputs on K2B: PC12 (pin 12) and PC7 (pin 14). Note: Other pins may require disabling default functions.

Control methods: gpio-leds (Linux kernel driver) or gpio_para (Allwinner driver).

gpio-leds Example (Heartbeat LED):

/{ 
    gpio-leds {
        compatible = "gpio-leds";
        status = "okay";
        sys_led {
            label="sys_led";
            gpio = <&pio PI 16 GPIO_ACTIVE_HIGH>;
            linux,default-trigger = "heartbeat";
        };
    };
};

gpio_para Example (PC7/PC12 Control):

&soc {
    gpio_para {
        gpio_num = <2>;
        gpio_pin_1 = <&pio PC 7 GPIO_ACTIVE_HIGH>;
        gpio_pin_2 = <&pio PC 12 GPIO_ACTIVE_HIGH>;
        status = "okay";
    };
};

Control commands:

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

GPIO Key Example:

/{ 
    gpio-keys {
        compatible = "gpio-keys";
        status = "okay";
        autorepeat;
        power {
            label = "Power Key";
            linux,code = <KEY_POWER>;
            gpio = <&pio PC 2 GPIO_ACTIVE_LOW>; // PC7
            wakeup-source;
            debounce-interval = <100>;
        };
    };
};

Serial Port

Test Tools

Use USB-to-TTL cable.

TTL Standard Serial Port

Connect using a serial port tool.

Software Testing Methods

ttyAS5 corresponds to serial port 5 (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

Modify UART Control Port

Change debug_uart to an unused UART (e.g., UART0 is reserved for U-Boot logs):

+++ b/source/kernel/linux-5.4-h618/arch/arm64/boot/dts/sunxi/uEnv/uEnv.txt
@@ -4,4 +4,4 @@ console=both
 disp_mode=1080p60
 fb0_width=1920
 fb0_height=1080
-debug_uart=ttyAS0
+debug_uart=ttyAS3

Add UART2 Support

PH6/PH7/PH8/PH9 default to SPI. PH4/PH5 default to I2C. To use PH5/PH6 as UART2:

Disable default functions.
Enable UART2 in the device tree.

TTL-to-485 Module Wiring

Connect to UART5:

TTL-to-232 Module Wiring

Connect to UART5:

Last updated 1 month ago