Unit PL031

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Description

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ARM PrimeCell PL031 Real Time Clock Driver unit

The PL031 is a simple memory mapped Real Time Clock (RTC) device that supports a single 32-bit time counter based on the Unix time format which starts at 1 Jan 1970 and runs out at 19 Jan 2038.

The device also includes a single alarm value which can trigger an interrupt when the selected time is reached.

This driver currently does not support reading or setting the alarm value.

Constants

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PL031 specific constants PL031_*

PL031_RTC_DESCRIPTION = 'ARM PrimeCell PL031 Real Time Clock';	Description of PL031 device
PL031_MIN_TIME = TIME_TICKS_TO_1970;	Time starts at 01/01/1970 00:00:00 (MM/DD/YY HH:MM:SS)
PL031_MAX_TIME = 137919572470000000;	Time ends at 19/1/2038 03:14:07 (MM/DD/YY HH:MM:SS)

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PL031 RTC control register PL031_RTC_CR_*

PL031_RTC_CR_EN = (1 shl 0);

If set to 1, the RTC is enabled. Once it is enabled, any writes to this bit have no effect on the RTC until a system reset. A read returns the status of the RTC.

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PL031 RTC interrupt mask set and clear register PL031_RTC_IMSC_*

PL031_RTC_IMSC_INTR_SET = (1 shl 0);
PL031_RTC_IMSC_INTR_CLEAR = (0 shl 0);

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PL031 RTC raw interrupt status register PL031_RTC_RIS_*

PL031_RTC_RIS_INTR = (1 shl 0);

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PL031 RTC masked interrupt status register PL031_RTC_MIS_*

PL031_RTC_MIS_INTR = (1 shl 0);

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PL031 RTC interrupt clear register PL031_RTC_ICR_*

PL031_RTC_ICR_INTR = (1 shl 0);

Type definitions

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PL031 real time clock (RTC) registers

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PPL031RTCRegisters = ^TPL031RTCRegisters;

TPL031RTCRegisters = record

Note: Layout of the PL031 registers (See: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0224b/i1005653.html)
DR:LongWord;	Data register
MR:LongWord;	Match register
LR:LongWord;	Load register
CR:LongWord;	Control register
IMSC:LongWord;	Interrupt mask set and clear register
RIS:LongWord;	Raw interrupt status register
MIS:LongWord;	Masked interrupt status register
ICR:LongWord;	Interrupt clear register

PL031 real time clock (RTC)

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PPL031RTC = ^TPL031RTC;

TPL031RTC = record

RTC Properties
RTC:TRTCDevice;
PL031 Properties
IRQ:LongWord;
Registers:PPL031RTCRegisters;	Device registers
Statistics Properties
InterruptCount:LongWord;	Number of interrupt requests received by the device

Public variables

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None defined

Function declarations

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PL031 functions

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function PL031RTCCreate(Address:PtrUInt; const Name:String; IRQ:LongWord):PRTCDevice;

Description: Create, register and start a new PL031 RTC device which can be accessed using the RTC API

Address	The address of the PL031 registers
Name	The text description of this device which will show in the device list (Optional)
IRQ	The interrupt number for the PL031
Return	Pointer to the new RTC device or nil if the RTC device could not be created

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function PL031RTCDestroy(RTC:PRTCDevice):LongWord;

Description: Stop, deregister and destroy a PL031 RTC device created by this driver

RTC	The RTC device to destroy
Return	ERROR_SUCCESS if completed or another error code on failure

PL031 RTC functions

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function PL031RTCStart(RTC:PRTCDevice):LongWord;

Description: Implementation of RTCDeviceStart API for PL031 RTC

Note	Not intended to be called directly by applications, use RTCDeviceStart instead.

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function PL031RTCStop(RTC:PRTCDevice):LongWord;

Description: Implementation of RTCDeviceStop API for PL031 RTC

Note	Not intended to be called directly by applications, use RTCDeviceStop instead.

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function PL031RTCGetTime(RTC:PRTCDevice):Int64;

Description: Implementation of RTCDeviceGetTime API for PL031 RTC

Note	Not intended to be called directly by applications, use RTCDeviceGetTime instead.

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function PL031RTCSetTime(RTC:PRTCDevice; const Time:Int64):Int64;

Description: Implementation of RTCDeviceSetTime API for PL031 RTC

Note	Not intended to be called directly by applications, use RTCDeviceSetTime instead.

PL031 helper functions

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function PL031FileTimeToRTCTime(RTC:PRTCDevice; const FileTime:Int64; var RTCTime:LongWord):Boolean;

Description: Convert a FileTime value in 100 nanosecond ticks since 1 January 1601 to the time format of the PL031 RTC which is seconds since 1 January 1970

Note	None documented

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function PL031RTCTimeToFileTime(RTC:PRTCDevice; RTCTime:LongWord; var FileTime:Int64):Boolean;

Description: Convert a PL031 RTC time value in seconds since 1 January 1970 to the FileTime format which is 100 nanosecond ticks since 1 January 1601

Note	None documented

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