Unit GPIO

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Description

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GPIO devices represent the external or internal pins available on most system on chip (SoC) devices to provide control and interfacing capabilities for both hardware and software.

This unit maintains pin numbering exactly as per the SoC documentation but abstracts other features such as alternate function selects to avoid exposing chip specific values via the API.

Not all GPIO devices support the same feature set so the GPIODeviceProperties function returns a structure which describes the number of pins as well as minimum and maximum pin numbers along with a set of flags that indicate what functionality is supported by the device.

Multiple GPIO devices can be accomodated, each one is registered with this unit when the driver for the device is loaded and initialized. This unit includes functions for enumerating the devices that are available and each function takes a GPIODevice parameter to allow specifying the exact device to control.

Simplified versions of many of the functions in this unit are provided in the Platform unit to allow control of the default GPIO device and in cases where there is only one device registered these functions will provide most of the capability required.

Constants

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To be documented

Type definitions

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To be documented

Public variables

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To be documented

Function declarations

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Initialization functions

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procedure GPIOInit;

Description: To be documented

Note	None documented

GPIO functions

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function GPIODeviceStart(GPIO:PGPIODevice):LongWord;

Description: Start the specified GPIO device and enable access

GPIO	The GPIO device to start
Return	ERROR_SUCCESS if completed or another error code on failure

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function GPIODeviceStop(GPIO:PGPIODevice):LongWord;

Description: Stop the specified GPIO device and disable access

GPIO	The GPIO device to stop
Return	ERROR_SUCCESS if completed or another error code on failure

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function GPIODeviceRead(GPIO:PGPIODevice; Reg:LongWord):LongWord;

Description: To be documented

Note	None documented

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procedure GPIODeviceWrite(GPIO:PGPIODevice; Reg,Value:LongWord);

Description: Perform a direct write to a register of the specified GPIO device

GPIO	The GPIO device to write to
Reg	The memory register to write to
Return	The value to write to the register

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function GPIODeviceInputGet(GPIO:PGPIODevice; Pin:LongWord):LongWord;

Description: To be documented

Note	None documented

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function GPIODeviceInputWait(GPIO:PGPIODevice; Pin,Trigger,Timeout:LongWord):LongWord;

Description: Wait for the state of a input pin to change on the specified GPIO device

GPIO	The GPIO device to wait for
Pin	The pin to wait for the state to change (eg GPIO_PIN_1)
Trigger	The trigger event to wait for (eg GPIO_TRIGGER_HIGH)
Timeout	Number of milliseconds to wait for the change (INFINITE to wait forever)
Return	The state after the change (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure or timeout

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function GPIODeviceInputEvent(GPIO:PGPIODevice; Pin,Trigger,Flags,Timeout:LongWord; Callback:TGPIOCallback; Data:Pointer):LongWord;

Description: Schedule a function to be called when the state of a input pin changes on the specified GPIO device

GPIO	The GPIO device to schedule the callback for
Pin	The pin to schedule the state change for (eg GPIO_PIN_1)
Trigger	The trigger event which will cause the function to be called (eg GPIO_TRIGGER_HIGH)
Timeout	The number of milliseconds before the scheduled trigger expires (INFINITE to never expire)
Callback	The function to be called when the trigger occurs
Data	A pointer to be pass to the function when the trigger occurs (Optional)
Return	ERROR_SUCCESS if the trigger was scheduled successfully or another error code on failure
Note	The pin and trigger that caused the event will be passed to the callback function

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function GPIODeviceInputCancel(GPIO:PGPIODevice; Pin:LongWord):LongWord;

Description: Cancel a previously scheduled event callback function for an input pin on the specified GPIO device

GPIO	The GPIO device to cancel the callback for
Pin	The pin to cancel the state change for (eg GPIO_PIN_1)
Return	ERROR_SUCCESS if the callback was cancelled successfully or another error code on failure

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function GPIODeviceOutputSet(GPIO:PGPIODevice; Pin,Level:LongWord):LongWord;

Description: Set the state of a output pin on the specified GPIO device

GPIO	The GPIO device to set for
Pin	The pin to set the state for (eg GPIO_PIN_1)
Level	The state to set the pin to (eg GPIO_LEVEL_HIGH)
Return	ERROR_SUCCESS if completed successfully or another error code on failure

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function GPIODevicePullGet(GPIO:PGPIODevice;Pin:LongWord):LongWord;

Description: Get the current pull state of a pin on the specified GPIO device

Pin	The pin to get the pull state for (eg GPIO_PIN_1)
Return	The current pull state of the pin (eg GPIO_PULL_UP) or GPIO_PULL_UNKNOWN on failure

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function GPIODevicePullSelect(GPIO:PGPIODevice; Pin,Mode:LongWord):LongWord;

Description: Change the pull state of a pin on the specified GPIO device

GPIO	The GPIO device to set for
Pin	The pin to change the pull state for (eg GPIO_PIN_1)
Mode	The pull state to set for the pin (eg GPIO_PULL_UP)
Return	ERROR_SUCCESS if completed successfully or another error code on failure

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function GPIODeviceFunctionGet(GPIO:PGPIODevice; Pin:LongWord):LongWord;

Description: Get the current function of a pin on the specified GPIO device

Note	None documented

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function GPIODeviceFunctionSelect(GPIO:PGPIODevice; Pin,Mode:LongWord):LongWord;

Description: To be documented

Note	None documented

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function GPIODeviceProperties(GPIO:PGPIODevice; Properties:PGPIOProperties):LongWord;

Description: To be documented

Note	None documented

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function GPIODeviceCreate:PGPIODevice;

Description: Create a new GPIO entry

Return	Pointer to new GPIO entry or nil if GPIO could not be created

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function GPIODeviceCreateEx(Size:LongWord):PGPIODevice;

Description: Create a new GPIO entry

Size	Size in bytes to allocate for new GPIO (Including the GPIO entry)
Return	Pointer to new GPIO entry or nil if GPIO could not be created

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function GPIODeviceDestroy(GPIO:PGPIODevice):LongWord;

Description: Destroy an existing GPIO entry

Note	None documented

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function GPIODeviceRegister(GPIO:PGPIODevice):LongWord;

Description: Register a new GPIO in the GPIO table

Note	None documented

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function GPIODeviceDeregister(GPIO:PGPIODevice):LongWord;

Description: Deregister a GPIO in the GPIO table

Note	None documented

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function GPIODeviceFind(GPIOId:LongWord):PGPIODevice;

Description: To be documented

Note	None documented

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function GPIODeviceFindByName(const Name:String):PGPIODevice; inline;

Description: To be documented

Note	None documented

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function GPIODeviceFindByDescription(const Description:String):PGPIODevice; inline;

Description: To be documented

Note	None documented

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function GPIODeviceEnumerate(Callback:TGPIOEnumerate; Data:Pointer):LongWord;

Description: To be documented

Note	None documented

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function GPIODeviceNotification(GPIO:PGPIODevice; Callback:TGPIONotification; Data:Pointer; Notification,Flags:LongWord):LongWord;

Description: To be documented

Note	None documented

RTL GPIO functions

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function SysGPIOAvailable:Boolean;

Description: Check if a GPIO device is available

Note	None documented

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function SysGPIOInputGet(Pin:LongWord):LongWord;

Description: Get the current state of a GPIO input pin

Pin	The pin to get the state for (eg GPIO_PIN_1)
Return	The current state (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure

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function SysGPIOInputWait(Pin,Trigger,Timeout:LongWord):LongWord;

Description: Wait for the state of a GPIO input pin to change

Pin	The pin to wait for the state to change (eg GPIO_PIN_1)
Trigger	The trigger event to wait for (eg GPIO_TRIGGER_HIGH)
Timeout	Number of milliseconds to wait for the change (INFINITE to wait forever)
Return	The state after the change (eg GPIO_LEVEL_HIGH) or GPIO_LEVEL_UNKNOWN on failure or timeout

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function SysGPIOInputEvent(Pin,Trigger,Timeout:LongWord; Callback:TGPIOCallback; Data:Pointer):LongWord;

Description: Schedule a function to be called when the state of a GPIO input pin changes

Pin	The pin to schedule the state change for (eg GPIO_PIN_1)
Trigger	The trigger event which will cause the function to be called (eg GPIO_TRIGGER_HIGH)
Timeout	The number of milliseconds before the scheduled trigger expires (INFINITE to never expire)
Callback	The function to be called when the trigger occurs
Data	A pointer to be pass to the function when the trigger occurs (Optional)
Return	ERROR_SUCCESS if the trigger was scheduled successfully or another error code on failure
Note	The pin and trigger that caused the event will be passed to the callback function

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function SysGPIOOutputSet(Pin,Level:LongWord):LongWord; 

Description: Set the state of a GPIO output pin

Pin	The pin to set the state for (eg GPIO_PIN_1)
Level	The state to set the pin to (eg GPIO_LEVEL_HIGH)
Return	ERROR_SUCCESS if completed successfully or another error code on failure

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function SysGPIOPullGet(Pin:LongWord):LongWord;

Description: Get the current pull state of a GPIO pin

Pin	The pin to get the pull state for (eg GPIO_PIN_1)
Return	The current pull state of the pin (eg GPIO_PULL_UP) or GPIO_PULL_UNKNOWN on failure

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function SysGPIOPullSelect(Pin,Mode:LongWord):LongWord;

Description: Change the pull state of a GPIO pin

Pin	The pin to change the pull state for (eg GPIO_PIN_1)
Mode	The pull state to set for the pin (eg GPIO_PULL_UP)
Return	ERROR_SUCCESS if completed successfully or another error code on failure

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function SysGPIOFunctionGet(Pin:LongWord):LongWord;

Description: Get the current function of a GPIO pin

Pin	The pin to get the function for (eg GPIO_PIN_1)
Return	The current function of the pin (eg GPIO_FUNCTION_IN) or GPIO_FUNCTION_UNKNOWN on failure

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function SysGPIOFunctionSelect(Pin,Mode:LongWord):LongWord;

Description: Change the function of a GPIO pin

Pin	The pin to change the function for (eg GPIO_PIN_1)
Mode	The function to set for the pin (eg GPIO_FUNCTION_OUT)
Return	ERROR_SUCCESS if completed successfully or another error code on failure

GPIO helper functions

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function GPIOGetCount:LongWord; inline;

Description: Get the current GPIO count

Note	None documented

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function GPIODeviceGetDefault:PGPIODevice; inline;

Description: Get the current default GPIO device

Note	None documented

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function GPIODeviceSetDefault(GPIO:PGPIODevice):LongWord;

Description: Set the current default GPIO device

Note	None documented

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function GPIODeviceCheck(GPIO:PGPIODevice):PGPIODevice;

Description: Check if the supplied GPIO is in the GPIO table

Note	None documented

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function GPIODeviceCreateEvent(GPIO:PGPIODevice; Pin:PGPIOPin; Callback:TGPIOCallback; Data:Pointer; Timeout:LongWord):PGPIOEvent;

Description: Create a new event using the supplied parameters

Note	Event must be registered by calling GPIODeviceRegisterEvent. Caller must hold the GPIO device lock.

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function GPIODeviceDestroyEvent(GPIO:PGPIODevice; Event:PGPIOEvent):LongWord;

Description: Destroy an existing event

Note	Event must be deregistered first by calling GPIODeviceDeregisterEvent. Caller must hold the GPIO device lock.

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function GPIODeviceRegisterEvent(GPIO:PGPIODevice; Pin:PGPIOPin; Event:PGPIOEvent):LongWord;

Description: Register an event in the event list of the supplied Pin

Note	Event must be created by calling GPIODeviceCreateEvent. Caller must hold the GPIO device lock.

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function GPIODeviceDeregisterEvent(GPIO:PGPIODevice;Pin:PGPIOPin;Event:PGPIOEvent):LongWord;

Description: Deregister an event in the event list of the supplied Pin

Note	Event must be destroyed by calling GPIODeviceDestroyEvent. Caller must hold the GPIO device lock.

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procedure GPIOLog(Level:LongWord; GPIO:PGPIODevice; const AText:String);

Description: To be documented

Note	None documented

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procedure GPIOLogInfo(GPIO:PGPIODevice; const AText:String);

Description: To be documented

Note	None documented

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procedure GPIOLogError(GPIO:PGPIODevice; const AText:String);

Description: To be documented

Note	None documented

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procedure GPIOLogDebug(GPIO:PGPIODevice; const AText:String);

Description: To be documented

Note	None documented

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function GPIOPinToString(Pin:LongWord):String;

Description: To be documented

Note	None documented

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function GPIOLevelToString(Level:LongWord):String;

Description: To be documented

Note	None documented

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function GPIOTriggerToString(Trigger:LongWord):String;

Description: To be documented

Note	None documented

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function GPIOPullToString(Value:LongWord):String;

Description: To be documented

Note	None documented

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function GPIOFunctionToString(Value:LongWord):String;

Description: To be documented

Note	None documented

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