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U3745bm, Configuration of the receiver – Rainbow Electronics U3745BM User Manual

Page 17

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U3745BM

4663A–RKE–06/03

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

Figure 17. Timing Diagram of the OFF Command Via Pin ENABLE

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.

Out1 (

m

C)

DATA (U3745BM)

Serial bi-directional
data line

X

Bit 1
("1")

X

t1

t2

t3

t4

t5

t7

X

X

(Start bit)

Startup mode

OFF Command

T

Receiver
on

t10

Sleep

ENABLE

DATA (U3745BM)

Serial bi-directional
data line

X

X

X

Sleep

X

toff

Receiver on

Startup mode

T

Doze

T