GPIO Access

  • Provides a set of functions to control GPIO pins.
  • Only supports the specific external GPIO controller : PCA9535 I/O expander on COM/SMARC Module
  • For Linux users on BMC controller, please refer to Step 7 of this page and install PCA9535 kernel driver on your target device. Please use GPIO sysfs Interface to access pins. We don’t provide any SEMA GPIO EAPI function on Linux environment.

sysfs Interface

  • To export the GPIO pin: (N should replace with gpio chip base number)

    echo N > /sys/class/gpio/export

  • To read the direction of a pin

    cat /sys/class/gpio/gpio251/direction

  • To write the direction of a pin

    echo in > /sys/class/gpio/gpio251/direction

  • To read the value of a pin

    cat /sys/class/gpio/gpio251/value

  • To write the value of a pin

    echo 1 > /sys/class/gpio/gpio251/value


SEMA EAPI (Only for Windows)

uint32_t EApiGPIOGetDirectionCaps(uint32_t Id, uint32_t* pnCapsIn, uint32_t* pnCapsOut)

Description

Get the capabilities of the current GPIO implementation from the selected GPIO interface. The ports where both input and output bit masks are 1 are GPIOs.

  • Parameters:

    • uint32_t Id

    • uint32_t* pnCapsIn:

      Pointer to a buffer that receives the bit mask of the supported inputs

    • uint32_t* pnCapsOut:

      Pointer to a buffer that receives the bit mask of the supported inputs


uint32_t EApiGPIOGetDirection(uint32_t GpioId, uint32_t Bitmask, uint32_t* pDirection)

Description

Reads the current configuration of the selected GPIO ports

  • Parameters:

    • uint32_t Id:

    • uint32_t Bitmask:

      Bit mask

    • uint32_t* pnCapsOut:

      Pointer to a buffer that receives the direction of the selected GPIO ports


uint32_t EApiGPIOSetDirection(uint32_t GpioId, uint32_t Bitmask, uint32_t pDirection)

Description

Sets the configuration for the selected GPIO ports

  • Parameters:

    • uint32_t GpioId:

    • uint32_t Bitmask:

      Bit mask. Only the ports with the level EAPI_GPIO_HIGHare processed

    • uuint32_t pDirection:

      Sets the direction of the selected GPIO ports. Bits with the value EAPI_GPIO_INPUT are inputs, bits with EAPI_GPIO_OUTPUT are outputs


uint32_t EApiGPIOGetLevel(uint32_t GpioId, uint32_t Bitmask, uint32_t* plevel)

Description

Read the from GPIO ports

  • Parameters:

    • uint32_t GpioId:

    • uint32_t Bitmask:

      Bit mask. Only selected bits are returned. Unselected bits return EAPI_GPIO_LOW

    • uint32_t* plevel:

      Pointer to a buffer that receives the GPIO level. Results can be read on a bit level


uint32_t EApiGPIOSetLevel(uint32_t GpioId, uint32_t Bitmask, uint32_t plevel)

Description

Write to GPIO ports. Depending on the hardware implementation writing multiple GPIO ports with the bit mask option does not guarantee a time synchronous change of the output levels. Any GPO level setting to the pins witch are configured with “Input” will not take effect. This function call will not return this as an error. Please make sure the Bitmask also mask the Input pins.

  • Parameters:

    • uint32_t GpioId:

    • uint32_t Bitmask:

      Value for a bit mask. Only selected bits are changed. Unselected bits remain unchanged

    • uint32_t* plevel:

      Input level of the selected GPIO port. Output for single ports is on a bit level