Rainbow-electronics DS1339 Bedienungsanleitung PDF herunterladen (Seite 8)

DS1339

8 of 18

Figure 4. SQUARE-WAVE OUTPUT FREQUENCY

RS2 RS1

SQUARE-WAVE OUTPUT

FREQUENCY

0 0 1Hz

0 1 4.096kHz

1 0 8.192kHz

1 1 32.768kHz

INTCN (Interrupt Control) – This bit controls the relationship between the two alarms and the interrupt

output pins. When the INTCN bit is set to logic 1, a match between the timekeeping registers and the

Alarm 1 or Alarm 2 registers activate the SQW/INT pin (provided that the alarms are enabled).When the

INTCN bit is set to logic 0, a square wave is output on the SQW/ INT pin. This bit is set to logic 0 when

power is first applied.

A1IE (Alarm 1 Interrupt Enable) – When set to logic 1, this bit permits the A1F bit in the status

logic 0, the A1F bit does not initiate the an interrupt signal. The A1IE bit is disabled (logic 0) when

power is first applied.

A2IE (Alarm 2 Interrupt Enable) – When set to a logic 1, this bit permits the A2F bit in the status

logic 0, the A2F bit does not initiate an interrupt signal. The A2IE bit is disabled (logic 0) when power is

first applied.

STATUS REGISTER (0Fh)

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

OSF 0 0 0 0 0 A2F A1F

OSF (Oscillator Stop Flag) – A logic 1 in this bit indicates that the oscillator either is stopped or was

stopped for some period of time and can be used to judge the validity of the clock and date data. This bit

is edge-triggered and set to logic 1 anytime the oscillator stops. The following are examples of conditions

that can cause the OSF bit to be set:

1) The first time power is applied.

2) The voltage present on both V

and V

BACKUP

are insufficient to support oscillation.

3) The EOSC bit is turned off.

4) External influences on the crystal (e.g., noise, leakage, etc.).

This bit remains at logic 1 until written to logic 0. This bit can only be written to a logic 0. Attempting to

write to logic 1 leaves the value unchanged.

A1F (Alarm 1 Flag) – A logic 1 in the A1F bit indicates that the time matched the Alarm 1 registers. If

the A1IE bit is a logic 1 and the INTCN bit is set to a logic 1, the SQW/ INT pin is also be asserted. A1F

1 2 3 4 5 6 7 8 9 10 11 12 13 ... 17 18

Keine Kommentare

Rainbow-electronics DS1339 Bedienungsanleitung Seite 8