Skip to main content

IR-RX

IR Functionality and Usage Guide.

Overview​

The Infrared Receiver (IR-RX) module captures and processes IR signals from remotes or other sources.

Functional Description​

On the K1 platform, an external infrared receiver (demodulator) receives the demodulated electrical signal, which is then decoded and reported as events within the driver and the kernel IR framework.

Source Code Structure​

The IR-RX controller driver code is located in the drivers/media/rc directory:

drivers/media/rc  
|--rc-ir-raw.c            # Kernel IR framework interface code
|--ir-nec-decoder.c       # Kernel IR decoder for NEC signal protocol  
|--ir-spacemit.c          # K1 IR driver

Key Features​

  • Configurable noise threshold
  • 32Bytes RX FIFO size

Configuration​

It mainly includes driver enablement configuration and dts configuration.

CONFIG Configuration​

CONFIG_IR_SPACEMIT=y

Symbol: IR_SPACEMIT [=y]
Device Drivers
    -> Remote Controller support (RC_CORE [=y])
  -> Remote Controller devices (RC_DEVICES [=y])
   -> SPACEMIT IR remote Recriver control (IR_SPACEMIT [=y])

DTS Configuration​

pinctrl​

You can refer to the PWM node configuration already set up in the Linux repository at: arch/riscv/boot/dts/spacemit/k1-x_pinctrl.dtsi as shown below:

 pinctrl_ir_rx_1: ir_rx_1_grp {
  pinctrl-single,pins = <
   K1X_PADCONF(GPIO_79, MUX_MODE1, (EDGE_NONE | PULL_UP | PAD_3V_DS4))     /* ir_rx */
  >;
 };

dtsi Configuration Example​

Configure the base address of the IR controller and the clock reset resources in the dtsi file. Typically, these settings stay unchanged.

 ircrx: irc-rx@d4017f00 {
  compatible = "spacemit,k1x-irc";
  reg = <0x0 0xd4017f00 0x0 0x100>;
  interrupts = <69>;
  interrupt-parent = <&intc>;
  clocks = <&ccu CLK_IR>;
  resets = <&reset RESET_IR>;
  clock-frequency = <102400000>;
  status = "disabled";
 };

dts Configuration Example​

The complete DTS configuration is shown below.

 &ircrx {
  pinctrl-names = "default";
  pinctrl-0 = <&pinctrl_ir_rx_1>;
  status = "okay";
 };

Interface​

API​

Commonly used:

int ir_raw_event_store_with_filter(struct rc_dev *dev, struct ir_raw_event *ev)

The driver calls the interface implemented by the IR framework to complete signal storage, decoding, and event reporting in the interrupt callback function.

Testing​

You can use an external infrared demodulator connected to the K1 platform, link it to the IR-configured pin as mentioned above, send signals to the demodulator using a remote control, and receive the code values at the application layer.

FAQ​