U3745BM Datasheet, PDF (17/29 Pages) ATMEL Corporation – UHF ASK RECEIVER IC

U3745BM
this pulse, the sleep time T_Sleep elapses. The receiver remains in sleep mode as long as
ENABLE is held to ‘L’. If the receiver is polled exclusively by a microcontroller, T_Sleep can
be programmed to 0 to enable a instantaneous response time. This command is the
faster option than via pin DATA at the cost of an additional connection to the
microcontroller.
Figure 16. Timing Diagram of the OFF Command Via Pin DATA
t1
t2
t3
t5
t4
t10
t7
Out1 (mC)
DATA (U3745BM)
X
X
Serial bi-directional
X
data line
Receiver
on
Bit 1
("1")
(Start bit)
OFF Command
Figure 17. Timing Diagram of the OFF Command Via Pin ENABLE
T_Doze
T_Sleep
toff
ENABLE
T _Sleep
X
Startup mode
DATA (U3745BM)
X
Serial bi-directional
data line
X
Receiver on
X
X
Startup mode
Configuration of the
Receiver
The U3745BM receiver is configured via two 12-bit RAM registers called OPMODE and
LIMIT. The registers can be programmed by means of the bi-directional DATA port. If
the register contents have changed due to a voltage drop, this condition is indicated by a
certain output pattern called reset marker (RM). The receiver must be reprogrammed in
that case. After a power-on reset (POR), the registers are set to default mode. If the
receiver is operated in default mode, there is no need to program the registers.
Table 3 shows the structure of the registers. According to Table 2, bit 1 defines if the
receiver is set back to polling mode via the OFF command, (see section “Receiving
Mode”) or if it is programmed. Bit 2 represents the register address. It selects the appro-
priate register to be programmed.
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4663A–RKE–06/03