u3742bm ATMEL Corporation, u3742bm Datasheet - Page 18

• Manufacturer Part Number: u3742bm
• Description: Uhf Ask/fsk Receiver
• Manufacturer: ATMEL Corporation

Switching the Receiver Back
to Sleep Mode
Figure 21. Timing Diagram of the OFF-command via Pin DATA
18
DATA (U3742BM)
Out1 (microcontroller)
Serial bi-directional
data line
U3742BM
Receiving
mode
X
X
t
1
After the end of data transmission, the receiver remains active and random noise pulses
appear at pin DATA. The edge-to-edge time period t
pulses is equal to or slightly higher than T
The receiver can be set back to polling mode via pin DATA or via pin ENABLE.
When using pin DATA, this pin must be pulled to Low for the period t
microcontroller. Figure 21 illustrates the timing of the OFF command (see also Figure 25
on page 23). The minimum value of t
t
ing the reset marker. This item is explained in more detail in the section “Configuration
of the Receiver” on page 19. Setting the receiver to sleep mode via DATA is achieved
by programming bit 1 of the OPMODE register to be '1'. Only one sync pulse (t
issued.
The duration of the OFF command is determined by the sum of t
OFF command, the sleep time T
is limited. The resulting time constant t together with an optional external pull-up resistor
may not be exceeded to ensure proper operation.
If the receiver is set to polling mode via pin ENABLE, an 'L' pulse (T
at that pin. Figure 22 on page 19 illustrates the timing of that command. After the posi-
tive edge of this pulse, the sleep time T
mode as long as ENABLE is held to 'L'. If the receiver is polled exclusively by a micro-
controller, T
command is the faster option than via pin DATA at the cost of an additional connection
to the microcontroller.
1
OFF command
is not limited but it is recommended not to exceed the specified value to prevent eras-
t
2
t
Sleep
3
(Startbit)
t
Bit 1
("1")
4
can be programmed to 0 to enable a instantaneous response time. This
t
t
10
t
7
5
Sleep
elapses. Note that the capacitive load at pin DATA
1
depends on BR_Range. The maximum value for
DATA_min
Sleep
T
Sleep
elapses. The receiver remains in sleep
.
ee
of the majority of these noise
1
, t
Doze
1
2
by the connected
and t
) must be issued
Startup mode
4735A–RKE–11/03
10
. After the
3
) is