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U3742BM Datasheet, PDF (23/32 Pages) ATMEL Corporation – UHF ASK/FSK RECEIVER
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U3742BM
Figure 24. Timing of the Register Programming
Out1
(microcontroller)
t1
t2
t3
t5
t4 t6
t7
DATA (U3742BM)
X
Serial bi-directional
X
data line
Receiving
mode
Bit 1
("0")
(Startbit)
Bit 2
("1")
(Register-
select)
Programming frame
Bit 13
("0")
(Poll8)
t9
TSleep
t8
Bit 14
("1")
(Poll8R)
Startup
mode
Programming the
Configuration Register
The configuration registers are programmed serially via the bi-directional data line
according to Figure 24 and Figure 25.
Figure 25. One-wire Connection to a Microcontroller
U3742BM
Internal pull-up
resistor
Bi-directional
data line
DATA
I/O
Microcontroller
Data
(U3742BM)
Out 1 (microcontroller)
To start programming, the serial data line DATA is pulled to 'L' for the time period t1 by
the microcontroller. When DATA has been released, the receiver becomes the master
device. When the programming delay period t2 has elapsed, it emits 14 subsequent syn-
chronization pulses with the pulse length t3. After each of these pulses, a programming
window occurs. The delay until the program window starts is determined by t4, the dura-
tion is defined by t5. Within the programming window, the individual bits are set. If the
microcontroller pulls down pin DATA for the time period t7 during t5, the bit is set to '0'. If
no programming pulse t7 is issued, this bit is set to '1'. All 14 bits are subsequently pro-
grammed in this way. The time frame to program a bit is defined by t6.
Bit 14 is followed by the equivalent time window t9. During this window, the equivalent
acknowledge pulse t8 (E_Ack) occurs if the just programmed mode word is equivalent to
the mode word that was already stored in that register. E_Ack should be used to verify
that the mode word was correctly transferred to the register. The register must be pro-
grammed twice in that case.
Programming of a register is possible both during sleep and active mode of the receiver.
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