U3741BM Datasheet, PDF (22/32 Pages) ATMEL Corporation – UHF ASK RECEIVER IC

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
synchronization pulses with the pulse length t3. After each of these pulses, a program-
ming window occurs. The delay until the program window starts is determined by t4, the
duration 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 according
bit is set to ‘0’. If no programming pulse t7 is issued, this bit is set to ‘1’. All 14 bits are
subsequently programmed 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 mode word just programmed 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.
During programming, the LNA, LO, low-pass filter, IF-amplifier and the demodulator are
disabled.
The programming start pulse t1 initiates the programming of the configuration registers.
If bit 1 is set to ‘1’, it represents the OFF command to set the receiver back to polling
mode at the same time. For the length of the programming start pulse t1, the following
convention should be considered:
• t1(min) < t1 < 1535 × T_Clk: [t1(min) is the minimum specified value for the relevant
BR_Range]
Programming (respectively OFF command) is initiated if the receiver is not in reset
mode. If the receiver is in reset mode, programming (respectively Off command) is not
initiated, and the reset marker RM is still present at pin DATA.
This period is generally used to switch the receiver to polling mode. In a reset condition,
RM is not canceled by accident.
• t1 > 5632 × T_Clk
Programming (respectively OFF command) is initiated in any case. RM is cancelled if
present. This period is used if the connected microcontroller detected RM. If a configura-
tion register is programmed, this time period for t1 can generally be used.
Note that the capacitive load at pin DATA is limited. The resulting time constant t
together with an optional external pull-up resistor may not be exceeded to ensure proper
operation.
22 U3741BM
4662B–RKE–10/04