04-Expansion_Pins_Testing

GPIO

WiringKP Tool Usage

Check whether the system has WiringKP tools

which gpio

image-20250514102207335

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

image-20250314150200725

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%

image-20250514115200103

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%

image-20250514115347443

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

image-20250514115517926

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   

image-20250514115800211

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

image-20250514115920195

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:

image-20250326115428401

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

image-20250326133713399

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

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

image-20250326142700157

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

image-20250326142738724

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.

image-20241231145656021

TTL Standard Serial Port

Connect using a serial port tool.

66637824ee48c91b31130503a4400149

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:

1. Disable default functions.

2. Enable UART2 in the device tree.

cf9c366bb88d7214bc93412cbc0accb3

---

TTL-to-485 Module Wiring

Connect to UART5:

---

TTL-to-232 Module Wiring

Connect to UART5: