CM-X300: WinCE: GPIOs Programming

GPIO Sample Application

Overview

This GPIOSample application demonstrates basic functionality of CM-X300 GPIOs under Windows CE:

• How to configure a GPIO pin as output and manipulate it.
• How to configure a GPIO pin as input and respond to changes in signal level.
• How to setup an edge triggered event.

Application Behavior

The GPIOSample manipulates the following GPIOs:

• GPIO 122 (pin 12 of connector P13 on the SB-X300) - Set as output
• GPIO 124 (pin 14 of connector P13 on the SB-X300) - Set as input
• GPIO 128 (Pin 24 of connector P11 on the SB-X300) - Set as input. (pin 0 on GPIO extender 0)

GPIO122 voltage level may be monitored with a DVM or an oscilloscope. GPIO124 and GPIO128 may be controlled by an external switch or button.

The GPIOSample performs the following actions:

• Edge detection on GPIO124 (cpu GPIO). Event handler is registered with GPIORegisterInterrupt. The handler calls GPIOInterruptDone to indicate interrupt completion.
• Edge detection on GPIO128 (GPIO extender). Event handler is registered with GPIORegisterInterrupt. The handler calls GPIOInterruptDone to indicate interrupt completion.
• Clock simulation on GPIO122 with a period of 3 seconds.
• Input voltage level monitoring on GPIO122.

GPIO Driver API

Data Types

GPIO_VALUE

GPIO state enumeration

Values

GPIO_LOW

GPIO_HIGH

GPIO_EDGE_SETTINGS

Values

GPIO_REACT_ON_FALLING

GPIO_REACT_ON_RISING

GPIO_REACT_ON_BOTH

GPIO_DONT_REACT

GPIO_INTERRUPT

Fields

Name	Description
DWORD dwGpioNum
GPIO_EDGE_SETTINGS Edge
HANDLE Event

Functions

HANDLE GPIOOpen()

Opens an instance of the GPIO Driver.

Return Values

Returns a handle that should be used to access the driver. Nonzero indicates success.

void GPIOClose(HANDLE hDevice)

Closes the driver handle

Parameters

• hDevice - Handle to an open driver instance

BOOL GPIOSetValue(HANDLE hDevice,DWORD num, GPIO_VALUE val)

Sets the state of a GPIO.

Parameters

• hDevice - Handle to an open driver instance
• num - GPIO number.
• val - The desired logical state.

Return Values

TRUE - indicates success

FALSE - indicates failure

Remarks

Make sure the GPIO direction is setup as output.

BOOL GPIOGetValue(HANDLE hDevice,DWORD num,GPIO_VALUE *gpioVal)

Return the logical state of a GPIO.

Parameters

• hDevice - Handle to an open driver instance
• num - GPIO number.
• gpioVal - pointer to the GPIO state variable

Return Values

TRUE - indicates success

FALSE - indicates failure

Remarks

Make sure the GPIO direction is setup as input. Returned value for an output GPIO is undefined

BOOL GPIOSetAsInput(HANDLE hDevice, DWORD num)

Configures a GPIO as an input.

Parameters

• hDevice - Handle to an open driver instance.
• num - GPIO number.

Return Values

TRUE - indicates success

FALSE - indicates failure

BOOL GPIOSetAsOutput(HANDLE hDevice,DWORD num, GPIO_VALUE val)

Configures a GPIO as an output and sets its logical state.

Parameters

• hDevice - Handle to an open driver instance
• num - GPIO number.
• val - The initial GPIO value

Return Values

TRUE - indicates success

FALSE - indicates failure

BOOL GPIORegisterInterrupt(HANDLE hDevice,GPIO_INTERRUPT interrupt)

Registers a GPIO as an interrupt source. The interrupt is triggered according to the configuration in GPIO_INTERRUPT.Edge member settings.

Parameters

• hDevice - Handle to an open driver instance
• interrupt- data structure that defines parameters for the interrupt registration

Return Values

TRUE - indicates success.

FALSE - indicates failure

Remarks

• The handle for the interrupt event is stored in GPIO_INTERRUPT.Event

VOID GPIOInterruptDone(HANDLE hDevice, DWORD num)

Signals to the kernel that GPIO interrupt processing is complete.

Parameters

• hDevice - Handle to an open driver instance
• num - GPIO number.

Remarks

A program calls GPIOInterruptDone when it has completed the interrupt processing and is ready for another interrupt.

BOOL GPIOUnRegisterInterrupt(HANDLE hDevice, DWORD num)

Disables the GPIO hardware interrupt.

Parameters

• hDevice - Handle to an open driver instance
• num - GPIO number.

Return Values

TRUE - indicates success.

FALSE - indicates failure

Remarks

A program calls GPIOUnRegisterInterrupt to disable the hardware interrupt and to unregister the event that was registered by GPIOInterruptInitialize.