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RTC - Real Time Clock

MS_uC / dnd / V08

Programming MicrocontrollerRTC – Real Time Clock

Autumn term 2007

32K Byte 32K Byte Burst FlashBurst Flash

64K or 96K 64K or 96K Byte SRAM Byte SRAM

256K or 512K 256K or 512K Byte Burst Byte Burst

FlashFlash

OTP OTP MemMem

UARTUARTI2CI2CSPISPITIMTIMRTCRTC

EXT. EXT. Bus Bus

GPIOGPIO

USB USB 2.0FS 2.0FS

CAN CAN 2.0B 2.0B

Enet Enet MAC MAC

PFPFQ Q

BC BC

DMADMA

INTINTR R

CntlCntl

ARM96ARM966E 6E CORE CORE

w/DSPw/DSP96 MHz 96 MHz

CLK CLK CntlCntl

ADCADC

LVD LVD BODBOD

PLLPLL JTAJTAGG

ETMETM99

STR912FW44

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Specifics

Self-isolation Mode RTC continues to operate

After power down Supply voltage drops out

Automatically switches to alternate voltage source connected to VBATT pin (e.g.battery)

Isolated 32KHz osc. continues to operate

Tamper Detect (Manipulation) RTC time recorded

SRAM standby voltage source cut off to invalidate SRAM contents

Millisecond counter, wake-up function

Real Time ClockComplete Time of Day Clock

Time is in 24 hour modeBCD format

Millisecond resolution9999 year calendar (leap year support)

Programmable Alarm (1 month)Periodic Interrupt Generation

(1 – 512Hz)Tamper Detection

Clock Calibration Output

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC structure

Clock Generator

Time Register

Date Register

Alarm Register

Status Register

APB

BUS

Control Register

Power Switch

32.768KHz

Calibration clk 4096HzMilli-Second

Register

TamperDetection

VBAT

Tamper In

Control Logic

CompareTamper Intr

Periodic Intr

Alarm Intr

RTC Interrupt

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Block diagram (simplified)

Ref manual figure 26

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Register MAP

? On which memory address can you see the seconds counting up?

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC time registerRTC_TR

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC date registerRTC_DTR

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Alarm time registerRTC_ATR

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Milliseconds RegisterRTC_MILR

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Control RegisterRTC_CR

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Status RegisterRTC_SR

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC debug support in IDE

[Peripherals-I/O Ports]

RTC support so far:

=> There might be loss of JTAG connection when using the millisecond timer

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RTC - Real Time Clock

MS_uC / dnd / V08

RTC Configuration Flow

1. Take RTC out of reset and enable PCLK clock Set bits in SCU_PCGR1 and SCU_PRR1 registers

2. Set W bit in RTC Control register

3. Set the current Millisecond in Millisec Register

4. Set the current second, minute, hour and date in Time Register

5. Set Alarm Register if Alarm Interrupt is needed

6. Clear W bit in Control Register, RTC starts running

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RTC - Real Time Clock

MS_uC / dnd / V08

Peripheral Bridge 1 configuration"slow" peripherals

PCG1: Peripheral Clocking Gate Register 1: PRR1: Peripheral Reset Register 1:

RTC enabledAfter Reset: ports disabled

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RTC - Real Time Clock

MS_uC / dnd / V08

Watchdog (WDG)

What is a watch dog in a microcontroller?

A device that supervises correct functioning of the controller

What can watch dog do?

Just bark and say: "We ar not ok" or reset the controller

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RTC - Real Time Clock

MS_uC / dnd / V08

Watch Dog Timer

Watch Dog Timer Features 16-bit down Counter 8-bit clock Prescaler Two clock sources : PCLK or RTC clock Watch Dog or Free-running Timer mode Key Register to protect Timer from un-intended counter loading

PrescalerRegister

CounterRegister

KeyRegister

APB Bus

Pre-LoadRegister

ClockLogic

PCLK

RTC CLK

Load

16 Bit Counter

ControlRegister

WatchDogMode

TimerMode

WDGReset

WDGInterrupt

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RTC - Real Time Clock

MS_uC / dnd / V08

Watch Dog Timer Modes

Watch Dog Mode Once enabled, this mode cannot be cleared by software Generates Reset when the 16 bit down counter reaches 0 count Prevent WDG_reset by writing twice (A55A, 5AA5) to the Key

Register. Counter is re-loaded after the write

WDG Free running Timer Mode User can pre-load counter and control the counting start

Can read counter values from Counter Register Generate interrupt when down counter reaches end of count Interrupt can be disabled, end of count flag is set in Status

Register