Difference between revisions of "Unit GPIO"

Revision as of 06:29, 28 July 2016

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Description

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

To be documented

Type definitions

To be documented

Public variables

To be documented

Function declarations

Initialization functions

procedure GPIOInit;

GPIO functions

function GPIODeviceStart(GPIO:PGPIODevice):LongWord;

function GPIODeviceStop(GPIO:PGPIODevice):LongWord;

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

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

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

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

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

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

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

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