5

ATA5277 [Preliminary]

4669B–RKE–10/03

Figure 3. Wake-up by External Switch

In Figure 3, the IC is woken up by an external switch (pulled to ground). After a

debouncing time t

nected microcontroller via the DIO line. Note that this impulse is already the start bit of

the first command. After that, the ATA5277 waits for a control or status command from

the microcontroller. The carrier remains off as the configuration bit M_Wake (see control

command 2) is '0'.

Figure 4. Wake-up by External Switch, Automatic Field Generation

The wake-up event as shown in Figure 4 is the same as in Figure 3, except for the con-

figuration bit M_Wake which is '1'. The driver stage will start operation after the wake-up

command has been confirmed. This behaviour can be used to build up an LF field inde-

pendently of the connected microcontroller.

Figure 5. Wake-up by Connected Microcontroller, Automatic Field Generation

Figure 5 shows a wake-up event triggered by the connected microcontroller, which now

pulls the DIO line to ground. To prevent the ATA5277 from waking up due to noise on

the DIO line, there is also a debouncing time before it will start operation. In this exam-

ple, M_Wake is again '1', so the driver stage starts operation after the wake-up event

has been confirmed.

Ext. switch

DIO line

Carrier state

t

deb

t

wake

Ext. switch

DIO line

Carrier state

t

deb

t

wake

Ext. switch

DIO line

Carrier state

t

deb

t

wake