The NXP i.MX91 CPU has four GPIO ports. The number of GPIOs that each port can generate and control varies:
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GPIO1: 16 signals
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GPIO2: 30 signals
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GPIO3: 32 signals
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GPIO4: 30 signals
GPIOs on the ConnectCore 91 platforms
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On the ConnectCore 91 system-on-module:
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Many of the i.MX91 GPIOs are available at the system-on-module, multiplexed with other functions (labeled GPIOx_IOy where x is the port and y is the GPIO pin). See Hardware reference manuals for information about GPIO pins and their multiplexed functionality.
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On the ConnectCore 93 Development Kit, the expansion connectors allow direct access to some of the i.MX91 GPIOs.
GPIOs on the SOM and carrier board are used for many purposes, such as:
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Power enable line for transceivers
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Reset line for controllers
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Interrupt line
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User LED
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User button
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The GPIO lines See Hardware reference manuals for information on the jumper connections and the multiplexed functionality they select. |
Kernel configuration
Support for i.MX91 GPIOs is automatically provided through the non-visible option CONFIG_GPIO_VF610.
Kernel driver
The driver for the i.MX91 GPIO is located at:
| File | Description |
|---|---|
i.MX91 GPIO driver |
Device tree bindings and customization
The i.MX91 GPIO device tree binding is documented at
Documentation/devicetree/bindings/gpio/gpio-vf610.yaml.
One GPIO controller is defined for each i.MX91 GPIO port in the common i.MX91 device tree file:
gpio1: gpio@47400080 {
compatible = "fsl,imx93-gpio", "fsl,imx7ulp-gpio";
reg = <0x47400080 0x1000>, <0x47400040 0x40>;
gpio-controller;
#gpio-cells = <2>;
interrupts = <GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>;
interrupt-controller;
#interrupt-cells = <2>;
clocks = <&clk IMX93_CLK_GPIO1_GATE>,
<&clk IMX93_CLK_GPIO1_GATE>;
clock-names = "gpio", "port";
gpio-ranges = <&iomuxc 0 92 16>;
npgios = <16>;
};
[...]
gpio4: gpio@43830080 {
compatible = "fsl,imx93-gpio", "fsl,imx7ulp-gpio";
reg = <0x43830080 0x1000>, <0x43830040 0x40>;
gpio-controller;
#gpio-cells = <2>;
interrupts = <GIC_SPI 189 IRQ_TYPE_LEVEL_HIGH>;
interrupt-controller;
#interrupt-cells = <2>;
clocks = <&clk IMX93_CLK_GPIO4_GATE>,
<&clk IMX93_CLK_GPIO4_GATE>;
clock-names = "gpio", "port";
gpio-ranges = <&iomuxc 0 38 28>, <&iomuxc 28 36 2>;
ngpios = <30>;
};For example, on the ConnectCore 93 Development Kit, GPIO2_IO22 is used to reset the camera:
/* MIPI-CSI camera */
ov5640_mipi: ov5640_mipi@3c {
compatible = "ovti,ov5640";
reg = <0x3c>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_mipi>;
clocks = <&mipi_csi_xtal24m>;
clock-names = "xclk";
csi_id = <0>;
powerdown-gpios = <&gpio2 22 GPIO_ACTIVE_LOW>;
mclk = <24000000>;
mclk_source = <0>;
[...]
};IOMUX configuration
You must configure the pads that are to be used as i.MX91 GPIOs. See Pin multiplexing (IOMUX).
For GPIOs that are managed by other drivers, you must configure their pad IOMUX inside the driver node specific pinctrl-0 to work according to the specified interface functionalities.
For GPIOs that are not associated with any interface or that can’t be handled by a driver, see Configure independent pin IOMUX and pad control.
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ULED/BUTTON1 is GPIO3_IO07
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ULED/BUTTON2 is GPIO4_IO23
GPIO pads power domains
The i.MX91 GPIOs may work at 1.8 V or 3.3 V depending on the power domain of the pad they are on. To determine the working voltage of a given GPIO:
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Locate the pad of a given signal on the ConnectCore 93 Development Kit schematics. For instance, on the ConnectCore 93 Development Kit, signal
CAN2_STBYcomes from padSPI1_SCK(pad E17) of the ConnectCore 91 SOM:
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Locate this pad on the IOMUX section of the ConnectCore 91 Hardware Reference Manual. This table lists the associated GPIO of the pad, and the power domain it is on:
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In the example, the power domain is 3V3. If a different power domain applies, locate it on the ConnectCore 93 Development Kit schematics to determine its voltage.
Use the GPIOs
The package libgpiod (added by packagegroup-dey-core) provides a set of tools (such as gpioget, gpioset, etc.) for controlling the GPIOs from user space.
| You can still control the GPIOs from the sysfs, but this API is not recommended. See https://www.kernel.org/doc/html/latest/userspace-api/gpio/sysfs.html. |
Detect GPIO ports
Use gpiodetect to list the GPIO ports detected by the kernel:
# gpiodetect
gpiochip0 [47400080.gpio] (16 lines)
gpiochip1 [43810080.gpio] (30 lines)
gpiochip2 [43820080.gpio] (32 lines)
gpiochip3 [43830080.gpio] (30 lines)where:
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Ports
gpiochip0togpiochip3are the i.MX91 GPIO ports.
This nomenclature corresponds with GPIO1 to GPIO4, as shown in the i.MX91 reference manual.
Information about a GPIO port
Use gpioinfo to list the lines of a given port:
# gpioinfo gpiochip1
gpiochip1 - 30 lines:
line 0: unnamed unused input active-high
line 1: unnamed unused input active-high
line 2: unnamed unused input active-high
line 3: unnamed unused input active-high
line 4: unnamed unused input active-high
line 5: unnamed unused input active-high
line 6: unnamed unused input active-high
line 7: unnamed "reset" output active-low [used]
line 8: unnamed unused input active-high
line 9: unnamed unused input active-high
line 10: unnamed "rs485-rts-gpio" output active-high [used]
line 11: unnamed unused input active-high
line 12: unnamed "spi0 CS0" output active-low [used]
line 13: unnamed unused input active-high
line 14: unnamed unused input active-high
line 15: unnamed unused input active-high
line 16: unnamed unused input active-high
line 17: unnamed unused input active-high
line 18: unnamed "interrupt" input active-high [used]
line 19: unnamed unused input active-high
line 20: unnamed unused input active-high
line 21: unnamed unused input active-high
line 22: unnamed unused output active-high
line 23: unnamed unused input active-high
line 24: unnamed unused input active-high
line 25: unnamed unused input active-high
line 26: unnamed unused input active-high
line 27: unnamed unused input active-high
line 28: unnamed unused input active-high
line 29: unnamed "interrupt" input active-high [used]Set an output high/low
Use gpioset to set a i.MX91 GPIO as output, such as GPIO1_IO27.
Use =1 to set it high, or =0 to set it low:
# gpioset gpiochip1 27=1
# gpioset gpiochip1 27=0Read an input
Use gpioget to read the value of a i.MX91 GPIO input, such as GPIO1_IO27:
# gpioget gpiochip1 27
0Use a GPIO as interrupt
Use gpiomon to wait for an event on a given GPIO, such as GPIO1_IO27:
# gpiomon --num-events 1 --rising-edge gpiochip1 27See the README of libgpiod for more information on the usage of these tools.
Sample application
An example application called apix-gpio-example is included in the dey-examples-digiapix recipe (part of dey-examples package) of the meta-digi layer.
This application shows how to manage GPIO lines using the Digi APIx library on the ConnectCore 91 platform.
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By default, the Get Started with ConnectCore Cloud Services demo application seizes the user button.
To use the example, stop the |
Go to GitHub to see the application instructions and source code.
See GPIO API for more information about the GPIO APIx.
