AS3524 datasheet(37/124 Pages) AMSCO

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AS3524 C21 / C22

austriamicrosystems

Data Sheet, Confidential

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Revision 1.11

- 124

Load register, Timer1Load, Timer2Load

This is a 32-bit register containing the value from which the counter is to decrement. This is the value used to reload the counter when periodic

mode is enabled, and the current count reaches zero.

When this register is written to directly, the current count is immediately reset to the new value at the next rising edge of TIMCLK which is enabled

by TIMCLKEN.

The value in this register is also overwritten if the TimerXBGLoad register is written to, but the current count is not immediately affected.

If values are written to both the timerXLoad and TimerXBGLoad registers before an enabled rising edge on TIMCLK, the following occurs:

•

On the next enabled TIMCLK edge the value written to the TimerXLoad value replaces the current count value

•

Following this, eacht time the counter reaches zero, the current count value is reset to the value written to TimerXBGLoad.

Reading from the TimerXLoad register at any time after the two writes have occurred will retrieve the value written to TimerXBGLoad. That is, the

value read from TimerXLoad is always the value which will take effect for periodic mode after the next time the counter reaches zero.

Current value register, Timer1Value, Timer2Value

This register gives the current value of the decrementing counter.

Timer control register

Table 16 Timer control register

Name

Base

Default

Timer1Control, Timer2Control

AS3525_TIMER_BASE

0x20

Timer Control Register

Offset: 0x08, 0x28

Contains control bits of the PLLA register.

Bit

Bit Name

Default

Access

Bit Description

Timer Enable

R/W

Enable bit:

0: timer disabled (default)

1: timer enabled

Timer Mode

R/W

Mode bit

0: timer is in free-running mode (default)

1: timer is in periodic mode

Interrupt Enable

R/W

Interrupt enable bit

0: timer interrupt disabled

1: timer interrupt enabled (default)

RESERVED

Reserved bit, do not modify, and ignore on read

3:2

TimerPre

R/W

Prescale bits:

00: no prescale, clock is divided by 1 (default)

01: 4 stages of prescale, clock is divided by 16

10: 8 stages of prescale, clock is divided by 256

11: undefined, do not use

Timer Size

R/W

Selects 16/32 bit counter operation

0: 16 bit counter (default)

1: 32 bit counter

OneShotCount

R/W

Selects one-shot or wrapping counter mode

0: wrapping mode (default)

1: one-shot mode

Interrupt clear register, Timer1IntClr, Timer2IntClr

Any write to this register will clear the interrupt output from the counter

AS3524 Datasheet(PDF) 37 Page - ams AG

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