Rainbow-electronics DS2404 Manual do Utilizador descarregar pdf (Página 7)

DS2404

7 of 29

Alarm Registers

The alarm registers for the real-time clock, interval timer, and cycle counter all operate in the same

manner. When the value of a given counter equals the value in its associated alarm register, the

appropriate flag bit is set in the status register. If the corresponding interrupt enable bit(s) in the status

when an alarm occurs, access to the device becomes limited. (See “Status/Control”, “Interrupts”, and the

“Programmable Expiration” sections.)

STATUS/CONTROL REGISTERS

The status and control registers are the first two bytes of page 16 (see “Memory Map”, Figure 4).

Status Register

76543210

CCE

ITE RTE

CCF ITF RTF 0200h

RTF Real-time clock alarm flag

ITF Interval timer alarm flag

CCF Cycle counter alarm flag

When a given alarm occurs, the corresponding alarm flag is set to a logic 1. The alarm flag(s) is cleared

by reading the status register.

RTE

Real-time interrupt enable

ITE

Interval timer interrupt enable

CCE

Cycle counter interrupt enable

Writing any of the interrupt enable bits to a logic 0 will allow an interrupt condition to be generated when

its corresponding alarm flag is set (see “Interrupts” section).

Control Register

76543210

DSEL

START

STOP

MAN.

AUTO

OSC RO WPC WPI WPR 0201h

WPR Write protect real-time clock/alarm registers

WPI Write protect interval timer/alarm registers

WPC Write protect cycle counter/alarm registers

Don’t care bits Read Only

1 2 3 4 5 6 7 8 9 10 11 12 ... 28 29

Sem comentários

Rainbow-electronics DS2404 Manual do Utilizador Página 7