Last edited one month ago

Touchscreen hardware components

Applicable for STM32MP13x lines, STM32MP15x lines, STM32MP21x lines, STM32MP23x lines, STM32MP25x lines


1. Article purpose[edit | edit source]

The purpose of this article is to:

  • list the touchscreen hardware components that might be integrated in the different boards
  • link these components to the corresponding software framework(s)
  • point to the datasheet(s) of these components
  • explain, when necessary, how to configure these components

2. Software frameworks[edit | edit source]

Domain Peripheral Software components Comment
OP-TEE Linux STM32Cube
Visual and Inputs Goodix GT9147 Inputs framework[1] Touchscreen input driver
Visual and Inputs Goodix GT911 Inputs framework[1] Touchscreen input driver
Visual and Inputs FocalTech FT6236 Inputs framework[1] Touchscreen input driver
Visual and Inputs Ilitek ILI251x Inputs framework[1] Touchscreen input driver

3. Goodix GT9147[edit | edit source]

The Goodix GT9147 is a single-layer multi-touch capacitive touch controller driver.

For details and the datasheet please contact the GT9147 driver provider.

Info white.png Information
This touchscreen controller driver can be found on some STM32MP15 Evaluation boards.

3.1. Linux driver[edit | edit source]

Bindings: Documentation/devicetree/bindings/input/touchscreen/goodix.yaml

Sources: drivers/input/touchscreen/goodix.c

Devicetree example: arch/arm/boot/dts/st/stm32mp157d-ev1.dts 

...
&dsi {
	#address-cells = <1>;
	#size-cells = <0>;
	status = "okay";

	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		port@0 {
			reg = <0>;
			dsi_in: endpoint {
				remote-endpoint = <&ltdc_ep0_out>;
			};
		};

		port@1 {
			reg = <1>;
			dsi_out: endpoint {
				remote-endpoint = <&dsi_panel_in>;
			};
		};
	};

	panel_dsi: panel-dsi@0 {
		compatible = "raydium,rm68200";
		reg = <0>;
		reset-gpios = <&gpiof 15 GPIO_ACTIVE_LOW>;
		backlight = <&panel_backlight>;
		power-supply = <&v3v3>;
		status = "okay";

		port {
			dsi_panel_in: endpoint {
				remote-endpoint = <&dsi_out>;
			};
		};
	};
};


&i2c2 {
...
	stmfx: stmfx@42 {
		compatible = "st,stmfx-0300";
		reg = <0x42>;
		interrupts = <8 IRQ_TYPE_EDGE_RISING>;
		interrupt-parent = <&gpioi>;
		vdd-supply = <&v3v3>;

		stmfx_pinctrl: pinctrl {
			compatible = "st,stmfx-0300-pinctrl";
			gpio-controller;
			#gpio-cells = <2>;
			interrupt-controller;
			#interrupt-cells = <2>;
			gpio-ranges = <&stmfx_pinctrl 0 0 24>;

			goodix_pins: goodix {
				pins = "gpio14";
				bias-pull-down;
			};

			joystick_pins: joystick-pins {
				pins = "gpio0", "gpio1", "gpio2", "gpio3", "gpio4";
				bias-pull-down;
			};
		};
	};

	gt9147: goodix-ts@5d {
		compatible = "goodix,gt9147";
		reg = <0x5d>;
		panel = <&panel_dsi>;
		pinctrl-0 = <&goodix_pins>;
		pinctrl-names = "default";
		AVDD28-supply = <&v3v3>;
		VDDIO-supply = <&v3v3>;
		status = "okay";

		interrupts = <14 IRQ_TYPE_EDGE_RISING>;
		interrupt-parent = <&stmfx_pinctrl>;
	};
};

4. Goodix GT911[edit | edit source]

The Goodix GT911 is a single-layer multi-touch capacitive touch controller driver.

For details and the datasheet please contact the GT911 driver provider.

Info white.png Information
This touchscreen driver can be found in the Rocktech "RK043FN78H-CT661C" module found in:

4.1. Linux driver[edit | edit source]

Bindings: Documentation/devicetree/bindings/input/touchscreen/goodix.yaml

Sources: drivers/input/touchscreen/goodix.c

Devicetree examples: 

/ {
...
	panel_backlight: panel-backlight {
		compatible = "gpio-backlight";
		gpios = <&gpioe 12 GPIO_ACTIVE_HIGH>;
		default-on;
		default-brightness-level = <0>;
		status = "okay";
	};

	panel_rgb: panel-rgb {
		compatible = "rocktech,rk043fn48h", "panel-dpi";
		enable-gpios = <&gpioi 7 GPIO_ACTIVE_HIGH>;
		backlight = <&panel_backlight>;
		power-supply = <&scmi_v3v3_sw>;
		status = "okay";

		width-mm = <105>;
		height-mm = <67>;

		port {
			panel_in_rgb: endpoint {
				remote-endpoint = <&ltdc_out_rgb>;
			};
		};

		panel-timing {
			clock-frequency = <10000000>;
			hactive = <480>;
			vactive = <272>;
			hsync-len = <52>;
			hfront-porch = <10>;
			hback-porch = <10>;
			vsync-len = <10>;
			vfront-porch = <10>;
			vback-porch = <10>;
		};
	};

...
};

&i2c5 {
...
	goodix: goodix_ts@5d {
		compatible = "goodix,gt911";
		reg = <0x5d>;
		pinctrl-names = "default";
		pinctrl-0 = <&goodix_pins_a>;
		interrupt-parent = <&gpiof>;
		interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
	        reset-gpios = <&gpioh 2 GPIO_ACTIVE_LOW>;
	        AVDD28-supply = <&scmi_v3v3_sw>;
	        VDDIO-supply = <&scmi_v3v3_sw>;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <272>;
		status = "okay" ;
	};
};

&ltdc {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&ltdc_pins_a>;
	pinctrl-1 = <&ltdc_sleep_pins_a>;
	status = "okay";

	port {
		#address-cells = <1>;
		#size-cells = <0>;

		ltdc_out_rgb: endpoint@0 {
			reg = <0>;
			remote-endpoint = <&panel_in_rgb>;
		};
	};
};

/ {
...
	panel_backlight: panel-backlight {
		compatible = "gpio-backlight";
		gpios = <&gpiof 9 GPIO_ACTIVE_HIGH>;
		default-on;
		default-brightness-level = <1>;
		status = "okay";
	};

	panel_rgb: panel-rgb {
		compatible = "panel-dpi";
		enable-gpios = <&gpiog 4 GPIO_ACTIVE_HIGH>;
		backlight = <&panel_backlight>;
		power-supply = <&scmi_v3v3>;
		data-mapping = "bgr666";
		default-on;
		status = "okay";

		width-mm = <105>;
		height-mm = <67>;

		port {
			panel_in_rgb: endpoint {
				remote-endpoint = <&ltdc_out_rgb>;
			};
		};

		panel-timing {
			clock-frequency = <10000000>;
			hactive = <480>;
			vactive = <272>;
			hsync-len = <52>;
			hfront-porch = <10>;
			hback-porch = <10>;
			vsync-len = <10>;
			vfront-porch = <10>;
			vback-porch = <10>;
			hsync-active = <0>;
			vsync-active = <0>;
			de-active = <1>;
			pixelclk-active = <1>;
		};
	};
...
};
...
&i2c2 {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&i2c2_pins_a>;
	pinctrl-1 = <&i2c2_sleep_pins_a>;
	i2c-scl-rising-time-ns = <34>;
	i2c-scl-falling-time-ns = <2>;
	status = "okay";

	goodix: goodix-ts@5d {
		compatible = "goodix,gt911";
		reg = <0x5d>;
		pinctrl-names = "default";
		pinctrl-0 = <&goodix_pins_a>;
		interrupt-parent = <&gpiof>;
		interrupts = <4 IRQ_TYPE_EDGE_FALLING>;
		AVDD28-supply = <&scmi_v3v3>;
		VDDIO-supply = <&scmi_v3v3>;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <272>;
		status = "okay" ;
	};
...
};

&ltdc {
	pinctrl-names = "default", "sleep";
	pinctrl-0 = <&ltdc_pins_a>;
	pinctrl-1 = <&ltdc_sleep_pins_a>;
	default-on;
	status = "okay";

	port {
		ltdc_out_rgb: endpoint {
			remote-endpoint = <&panel_in_rgb>;
		};
	};
};

5. FocalTech FT6236[edit | edit source]

The FocalTech FT6236 is a self-capacitive touch panel controller driver.

For details and the datasheet please contact the FT6236 driver provider.

Info white.png Information
This touchscreen controller driver can be found on some STM32MP15 Discovery kits.

5.1. Linux driver[edit | edit source]

Bindings: Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.yaml

Sources: drivers/input/touchscreen/edt-ft5x06.c

Devicetree example: arch/arm/boot/dts/st/stm32mp157f-dk2.dts 

&dsi {
	status = "okay";

	ports {
		port@0 {
			reg = <0>;
			dsi_in: endpoint {
				remote-endpoint = <&ltdc_ep1_out>;
			};
		};

		port@1 {
			reg = <1>;
			dsi_out: endpoint {
				remote-endpoint = <&panel_in>;
			};
		};
	};

	panel_otm8009a: panel-otm8009a@0 {
		compatible = "orisetech,otm8009a";
		reg = <0>;
		reset-gpios = <&gpioe 4 GPIO_ACTIVE_LOW>;
		power-supply = <&v3v3>;
		status = "okay";

		port {
			panel_in: endpoint {
				remote-endpoint = <&dsi_out>;
			};
		};
	};
};

&i2c1 {
	touchscreen@2a {
		compatible = "focaltech,ft6236";
		reg = <0x2a>;
		interrupts = <2 2>;
		interrupt-parent = <&gpiof>;
		interrupt-controller;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <800>;
		panel = <&panel_otm8009a>;
		vcc-supply = <&v3v3>;
		iovcc-supply = <&v3v3>;
		status = "okay";
	};
	touchscreen@38 {
		compatible = "focaltech,ft6236";
		reg = <0x38>;
		interrupts = <2 2>;
		interrupt-parent = <&gpiof>;
		interrupt-controller;
		touchscreen-size-x = <480>;
		touchscreen-size-y = <800>;
		panel = <&panel_otm8009a>;
		vcc-supply = <&v3v3>;
		iovcc-supply = <&v3v3>;
		status = "okay";
	};
};

&ltdc {
	status = "okay";

	port {
		ltdc_ep1_out: endpoint@1 {
			reg = <1>;
			remote-endpoint = <&dsi_in>;
		};
	};
};

6. Ilitek ILI251x[edit | edit source]

The Ilitek ILI251x is a multi-touch capacitive touch controller driver.

For details and the datasheet please contact the ILI251x driver provider.

Info white.png Information
This touchscreen driver can be found in the EDT ETML0700Z9NDHA module found in:

6.1. Linux driver[edit | edit source]

Bindings: Documentation/devicetree/bindings/input/touchscreen/ilitek_ts_i2c.yaml

Sources: drivers/input/touchscreen/ilitek_ts_i2c.c

Devicetree example: arch/arm64/boot/dts/st/stm32mp257f-ev1.dts 

...
/ {
...
	panel_dsi_backlight: panel-dsi-backlight {
		compatible = "gpio-backlight";
		gpios = <&gpioi 5 GPIO_ACTIVE_LOW>;
		default-on;
		default-brightness-level = <0>;
		status = "disabled";
	};

	panel_lvds: panel-lvds {
		compatible = "edt,etml0700z9ndha", "panel-lvds";
		enable-gpios = <&gpiog 15 GPIO_ACTIVE_HIGH>;
		backlight = <&panel_lvds_backlight>;
		status = "okay";

		width-mm = <156>;
		height-mm = <92>;
		data-mapping = "vesa-24";

		panel-timing {
			clock-frequency = <54000000>;
			hactive = <1024>;
			vactive = <600>;
			hfront-porch = <150>;
			hback-porch = <150>;
			hsync-len = <21>;
			vfront-porch = <24>;
			vback-porch = <24>;
			vsync-len = <21>;
		};

		port {
			lvds_panel_in: endpoint {
				remote-endpoint = <&lvds_out0>;
			};
		};
	};

	panel_lvds_backlight: panel-lvds-backlight {
		compatible = "gpio-backlight";
		gpios = <&gpioi 5 GPIO_ACTIVE_HIGH>;
		default-on;
		default-brightness-level = <0>;
		status = "okay";
	};
...
};

...
&i2c2 {
...
	ili2511: ili2511@41 {
		compatible = "ilitek,ili251x";
		reg = <0x41>;
		interrupt-parent = <&gpioi>;
		interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
		reset-gpios = <&gpiog 14 GPIO_ACTIVE_LOW>;
		status = "okay";
	};
};
...
&ltdc {
	rotation-memory = <&ltdc_sec_rotation>;
	status = "okay";

	port {
		#address-cells = <1>;
		#size-cells = <0>;

		ltdc_ep0_out: endpoint@0 {
			reg = <0>;
			remote-endpoint = <&dsi_in>;
		};

		ltdc_ep1_out: endpoint@1 {
			reg = <1>;
			remote-endpoint = <&lvds_in>;
		};
	};
};

&lvds {
	status = "okay";

	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		port@0 {
			reg = <0>;
			lvds_in: endpoint {
				remote-endpoint = <&ltdc_ep1_out>;
			};
		};

		port@1 {
			reg = <1>;
			lvds_out0: endpoint {
				remote-endpoint = <&lvds_panel_in>;
			};
		};
	};
};

7. To go further[edit | edit source]

Related articles:

DRM KMS
Display bridges hardware components
Display panels hardware components
DRM KMS overview
DRM KMS troubleshooting grid
DSI device tree configuration
How to display on HDMI
How to find the description of a color format and check its support
How to get DRM KMS logs
How to get name and current status of a DRM connector
How to modify the panel backlight
How to monitor the display framerate
How to use the DSI video mode pattern generator for signal quality measurements
How to use the LVDS PRBS Generator for signal quality measurements
How to write a display panel or bridge driver
How to write a low resolution and slow interface display panel driver
LTDC device tree configuration
LVDS device tree configuration
Touchscreen hardware components

8. References[edit | edit source]

  1. ↑ 1.0 1.1 1.2 1.3 Linux Input Subsystem kernel API and userspace API



Open portable trusted execution environment

Linux® is a registered trademark of Linus Torvalds.

General-purpose input/output (A realization of open ended transmission between devices on an embedded level. These pins available on a processor can be programmed to be used to either accept input or provide output to external devices depending on user desires and applications requirements.)

Open portable trusted execution environment

Linux® is a registered trademark of Linus Torvalds.

General-purpose input/output (A realization of open ended transmission between devices on an embedded level. These pins available on a processor can be programmed to be used to either accept input or provide output to external devices depending on user desires and applications requirements.)

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