Peripheral Adaptation

CAM-CRV1126S2U/CAM-C1109S2U retains a wealth of expansion interfaces, including Ethernet, USB, Serial port, GPIO, I2C, I2S, SPI, SDIO, etc. Basically meet all the expansion needs of customers. This chapter mainly describes some simple peripherals that may be used by the gates.

Relay

The essence of the relay is to operate GPIO, here is how to operate GPIO in the system.

• Check the interface definition and select the GPIO to be manipulated, such as GPIO3_D6

• Calculate GPIO number

# GPIO3_D6
3 x 32 + 3 x 8 + 6 = 126
# Formula GPIO(X)_(Y)(Z)
# Where the variable Y ：A = 0，B = 1，C = 2，D = 3
X x 32 + Y x 8 + Z

• Register GPIO

echo 126 > /sys/class/gpio/export

# Need to confirm that the GPIO is not occupied and not initialized other functions
# If GPIO3_D6 is also the I2S_m0 port, I2S needs to be disabled in the kernel
vim sdk/kernel/arch/arm/boot/dts/rv1109-firefly-ai-cam.dts (rv1126-firefly-ai-cam.dts)
# Add the following code at the end
&i2s0 {
	status = "disabled";
};
# Compile and upgrade the kernel

• Set GPIO to output mode

echo out > /sys/class/gpio/gpio126/direction

• Set GPIO output high/low level

echo 1 > /sys/class/gpio/gpio126/value # high level
echo 0 > /sys/class/gpio/gpio126/value # low level

LED

• Select the GPIO port, modify the kernel device tree, and add a custom LED device node.

vim sdk/kernel/arch/arm/boot/dts/rv1109-firefly-ai-cam.dts (rv1126-firefly-ai-cam.dts)
# Refer to the following configuration to add LED nodes.
 leds {
    compatible = "gpio-leds";

    user_led: user {
        label = "firefly:yellow:user";
        linux,default-trigger = "ir-user-click";
        default-state = "off";
        gpios = <&gpio3 RK_PD6 GPIO_ACTIVE_HIGH>;
        pinctrl-names = "default";
        pinctrl-0 = <&led_user>;
    };
};

# pinctrl needs to add GPIO multiplexing control
led_user: led-user {
	rockchip,pins = <3 RK_PD6 RK_FUNC_GPIO &pcfg_pull_none>;
};

# Compile and upgrade the kernel after modification

• Control LED

echo 1 > /sys/class/leds/firefly:yellow:user/brightness # Light up
echo 0 > /sys/class/leds/firefly:yellow:user/brightness # Light off