Mike at 14:59, 15 March 2010

2010-03-15T14:59:09Z

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== GPIO Sample Application ==
=== Overview ===

This GPIOSample application demonstrates basic functionality of EM-X270 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 ===
Prerequisites for the application:
* A demo keypad provided with the EM-X270 evaluation kit.

The GPIOSample manipulates the following GPIOs:
* GPIO 22 (pin 10 of P2 connector on the Keypad Demo Board) - Set as output
* GPIO 36 (pin 9 of P2 connector on the Keypad Demo Board) - Set as input
* GPIO 96 (pin 8 of P2 connector on the Keypad Demo Board) - Set as input
* GPIO 107 (pin 5 of P2 connector on the Keypad Demo Board) - Set as input

GPIO22 voltage level may be monitored with a DVM or an oscilloscope. GPIO36, GPIO96 and GPIO107 may be controlled by an external switch or button.

The GPIOSample performs the following actions:
* Edge detection on GPIO107 . Event handler is registered with [[#DWORD_GPIORegisterInterrupt.28HANDLE_hDevice.2CGPIO_INTERRUPT_interrupt.29|GPIORegisterInterrupt]]. The handler calls [[#BOOL_GPIOInterruptDone.28HANDLE_hDevice.2C_DWORD_num.29|GPIOInterruptDone]] to indicate interrupt completion.
* Clock simulation on GPIO22 with a period of 3 seconds.
* Input voltage level monitoring on GPIO36.
* Polling on GPIO96 until it is asserted.

=== Available GPIOs ===
The following table specifies GPIOs available on the EM-X270 platform:
{| cellpadding="3" border="1" style="border: 1px solid rgb(85, 85, 85); border-collapse: collapse;"
| '''GPIO#''' || '''PXA27X Alternate Function''' || '''Conflicts with EM-X270 demo keypad driver''' || '''Pin# on keypad extender (P2)'''
|-
| 22 || KP_MKOUT<7> || No || 10
|-
| 34 || KP_MKIN<3> || No || 1
|-
| 36 || KP_MKIN<7> || No || 9
|-
| 39 || KP_MKIN<4> || No || 3
|-
| 91 || KP_MKIN<6> || No || 7
|-
| 96 || KP_MKOUT<6> || No || 8
|-
| 99 || KP_MKIN<5> || No || 5
|-
| 106 || KP_MKOUT<3> || No || 2
|-
| 107 || KP_MKOUT<4> || No || 4
|-
| 108 || KP_MKOUT<5> || No || 6
|-
| 100 || KP_MKIN<0> || Yes || -
|-
| 101 || KP_MKIN<1> || Yes || -
|-
| 102 || KP_MKIN<2> || Yes || -
|-
| 103 || KP_MKOUT<0> || Yes || -
|-
| 104 || KP_MKOUT<1> || Yes || -
|-
| 105 || KP_MKOUT<2> || Yes || -
|}

{{Note| If your application does not require keypad, you can remove EM-X270 Keypad driver from the Catalog and reuse GPIO100-GPIO105.}}

== GPIO Driver API ==
=== Data Types ===
{{Enum| HeadLevel = ==== | Enumname = GPIO_VALUE |
Description = GPIO state enumeration|
Field1 = GPIO_LOW |
Field2 = GPIO_HIGH |
Field3 = |
Field4 = |
Remarks = |
}}

{{Enum| HeadLevel = ==== | Enumname = GPIO_EDGE_SETTINGS |
Description = |
Field1 = GPIO_REACT_ON_FALLING |
Field2 = GPIO_REACT_ON_RISING |
Field3 = GPIO_REACT_ON_BOTH |
Field4 = GPIO_DONT_REACT |
Remarks = |
}}

{{Struct| HeadLevel = ==== | Structname = GPIO_INTERRUPT |
Description = |
Field1 = DWORD dwGpioNum |
Fieldexp1 = |
Field2 = [[#GPIO_EDGE_SETTINGS|GPIO_EDGE_SETTINGS]] Edge|
Fieldexp2 = |
Field3 = HANDLE Event|
Fieldexp3 = |
Field4 = |
Field5 = |
Field6 = |
Field7 = |
Field8 = |
Remarks = |
}}

=== Functions ===
{{APIEx| HeadLevel = ==== | Signature = HANDLE GPIOOpen() |
Description = Opens an instance of the GPIO Driver. |
Return = Returns a handle that should be used to access the driver. Nonzero indicates success. |
Param1 = |
Param2 = |
Param3 = |
Param4 = |
Remarks = }}

{{APIEx| HeadLevel = ==== | Signature = void GPIOClose(HANDLE hDevice) |
Description = Closes the driver handle |
Return = |
Param1 = *hDevice - Handle to an open driver instance|
Param2 = |
Param3 = |
Param4 = |
Remarks = }}

{{APIEx| HeadLevel = ==== | Signature = BOOL GPIOSetValue(HANDLE hDevice,DWORD num, [[#GPIO_VALUE|GPIO_VALUE]] val) |
Description = Sets the state of a GPIO. |
Return = TRUE - indicates success
:FALSE - indicates failure|
Param1 = *hDevice - Handle to an open driver instance|
Param2 = *num - GPIO number.|
Param3 = *val - The desired logical state. |
Param4 = |
Remarks = Make sure the GPIO direction is setup as output.}}

{{APIEx| HeadLevel = ==== | Signature = BOOL GPIOGetValue(HANDLE hDevice,DWORD num,[[#GPIO_VALUE|GPIO_VALUE]] *gpioVal) |
Description = Return the logical state of a GPIO.|
Return = TRUE - indicates success
:FALSE - indicates failure|
Param1 = *hDevice - Handle to an open driver instance|
Param2 = *num - GPIO number.|
Param3 = *gpioVal - pointer to the GPIO state variable|
Param4 = |
Remarks = Make sure the GPIO direction is setup as input. Returned value for an output GPIO is undefined}}

{{APIEx| HeadLevel = ==== | Signature = void GPIOSetAsInput(HANDLE hDevice, DWORD num) |
Description = Configures a GPIO as an input.|
Return = TRUE - indicates success
:FALSE - indicates failure|
Param1 = *hDevice - Handle to an open driver instance.|
Param2 = *num - GPIO number.|
Param3 = |
Param4 = |
Remarks = }}

{{APIEx| HeadLevel = ==== | Signature = BOOL GPIOSetAsOutput(HANDLE hDevice,DWORD num, [[#GPIO_VALUE|GPIO_VALUE]] val) |
Description = Configures a GPIO as an output and sets its logical state. |
Return = TRUE - indicates success
:FALSE - indicates failure|
Param1 = *hDevice - Handle to an open driver instance|
Param2 = *num - GPIO number.|
Param3 = *val - The initial GPIO value|
Param4 = |
Remarks = }}

{{APIEx| HeadLevel = ==== | Signature = DWORD GPIORegisterInterrupt(HANDLE hDevice,[[#GPIO_INTERRUPT|GPIO_INTERRUPT]] interrupt) |
Description = Registers a GPIO as an interrupt source. The interrupt is triggered according to the configuration in [[#GPIO_INTERRUPT|GPIO_INTERRUPT]].Edge member settings. |
Return = TRUE - indicates success. The handle for the interrupt event is stored in [[#GPIO_INTERRUPT|GPIO_INTERRUPT]].Event|
Param1 = *hDevice - Handle to an open driver instance|
Param2 = *interrupt- data structure that defines parameters for the interrupt registration
<pre>
struct gpio_intr_t{
DWORD dwGpioNum;
GPIO_EDGE_SETTINGS Edge;
HANDLE Event;
} GPIO_INTERRUPT;
</pre> |
Param3 = |
Param4 = |
Remarks = * This function must be called before using the [[#GPIO_INTERRUPT|GPIO_INTERRUPT]].Event parameter.
:* The [[#GPIO_INTERRUPT|GPIO_INTERRUPT]].Event parameter may only be used in a {{Cmd|WaitForSingleObject}} call. A {{Cmd|WaitForMultipleObjects}} call with [[#GPIO_INTERRUPT|GPIO_INTERRUPT]].Event will fail.
:* If you use GPIO_INTERRUPT.Event in a call to WaitForSingleObject before you call {{Cmd|GPIOInterruptInitialize}}, {{Cmd|GPIOInterruptInitialize}} will fail.
}}

{{APIEx| HeadLevel = ==== | Signature = BOOL GPIOInterruptDone(HANDLE hDevice, DWORD num) |
Description = Signals to the kernel that GPIO interrupt processing is complete.|
Return = TRUE- indicates success. |
Param1 = *hDevice - Handle to an open driver instance|
Param2 = *num - GPIO number.|
Param3 = |
Param4 = |
Remarks = A program calls {{Cmd|GPIOInterruptDone}} when it has completed the interrupt processing and is ready for another interrupt.}}

{{APIEx| HeadLevel = ==== | Signature = DWORD GPIOUnRegisterInterrupt(HANDLE hDevice, DWORD num) |
Description = Disables the GPIO hardware interrupt.|
Return = TRUE - indicates success. |
Param1 = *hDevice - Handle to an open driver instance|
Param2 = *num - GPIO number.|
Param3 = |
Param4 = |
Remarks = A program calls {{Cmd|GPIOUnRegisterInterrupt}} to disable the hardware interrupt and to unregister the event that was registered by {{Cmd|GPIOInterruptInitialize}}.}}
{{Note|The exact definition of GPIO API is located in the gpio.h file in the GPIOSample project.}}

[[Category:Windows CE|GPIOs Programming]]
[[Category:EM-X270|WinCE: GPIOs Programming]]

EM-X270: WinCE: GPIOs Programming - Revision history

Mike at 14:59, 15 March 2010