22
4899B–RKE–10/06
ATA3741
Figure 5-15. One-wire Connection to a Microcontroller
To start programming, the serial data line DATA is pulled to “L” by the microcontroller for the
time period t1. 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 programming window occurs. The delay
until the program window starts is determined by t4, the duration is defined by t5. Within the pro-
gramming 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 acknowl-
edge 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 programmed 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 (or the OFF command) is initiated if the receiver is not in reset mode. If the
receiver is in reset mode, programming (or the 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 (or the OFF command) is initiated in any case. RM is cancelled if present. This
period is used if the connected microcontroller detected RM. If a configuration register is pro-
grammed, 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 should not be exceeded, to ensure proper operation.
Internal pull-up
resistor
Bi-directional
data line
DATA
I/O
ATA3741
Microcontroller
DATA (ATA3741)
Out 1 (microcontroller)
