A²SI™
Data Sheet Advanced AS-Interface IC
Revision 2.2
June 2001
Pages (total): 28 8
If the received telegram contained an error, the
Control-Unit will not generate the REC-STRB signal
but go to its asynchronous state waiting for a pause
at the IRD input. After a pause was detected, the
UART is ready to receive the next telegram from the
IRD input.
If a REC-STRB signal is generated, it occurs 9.5 µs
up to 10.0 µs (Synchronous Mode) or 21.0 µs up to
21.5 µs (Asynchronous Mode), respectively, after the
rising edge of the End-Bit on the IRD pin signal. If the
slave was in asynchronous state, it now transforms to
synchronous state. The Rec-Muxer is locked to the
IRD input until the next IC-reset. After the generation
of a REC-STRB signal the Control-Unit is waiting for
about 6.0 µs for the SEND-STRB to be generated by
the Main-State-Machine.
If the Control-Unit receives the active high SEND-
STRB signal, it starts the transmission of the Send-
Register data. Therefore, the Send-Register data will
be converted to an active low Manchester II-coded
(MAN) signal which is sent to the LED-OUT pin via
ADD-OUT. The first falling edge of the MAN signal
occurs 11.75 µs (Synchronous Mode) or 12.25 µs
(Asynchronous Mode) after the rising edge of the
REC-STRB signal. Hence, the delay from the rising
edge of the End-Bit of the master call (IRD input) to
the first falling edge of the slave response (LED
output) is 21.25 to 21.75 µs (Synchronous Mode) or
33.25 to 33.75 µs (Asynchronous Mode). After the
pause was detected, the UART is ready to receive
the next telegram from the IRD input.
In case the Control-Unit will not receive a SEND-
STRB signal within the given time frame (for
instance, if this slave was not addressed), it will
check for activity on the IRD input. Otherwise, it will
just wait for the end of the response time (60 µs). In
both cases the Control-Unit stays synchronous. Once
a slave pause was detected, the UART is ready to
receive the next telegram from the IRD input.
7.1.2.2 AS-i Input Mode
A signal on the AS-i-line generates two pulse-coded
signals (N-PULSE, P-PULSE) at the receiver output
with a minimum pulse width of 750 to 875 ns. A pulse
on the AS-i line starts the receiver and triggers the
Activity-Checker through N-PULSE or P-PULSE.
The Pulse-Encoder is used to convert the active high
pulse coded signal to an active low Manchester-II-
coded (MAN) signal. It will also check the pulse
stream for timing and pulse errors (e.g. alternation
error). The Control-Unit enables the Receive-Register
so that the received information can be clocked in
every 6 µs. If there is a pulse distance on the AS-i-
line input longer than 7.0 µs, the Control-Unit
recognizes this as no activity and disables the
Receive-Register.
If the received information is a correct master call
with Start-Bit, eleven (11) Data-Bits, Parity-Bit, End-
Bit, and following pause of either greater than 6.0 µs
(Synchronous Mode) or 18.0 µs (Asynchronous
Mode), the UART generates the internal active high
REC-STRB signal. If the received telegram contained
an error, the Control-Unit will not generate the REC-
STRB signal but go to its asynchronous state waiting
for a pause at the AS-i line input. After a pause was
detected the UART is ready to receive the next
telegram from the AS-i line input.
If a REC-STRB signal is generated, it occurs 10.0 to
10.5 µs (Synchronous Mode) or 21.5 to 22 µs
(Asynchronous Mode), respectively, after the rising
edge (receiver comparator switching point) of the
End-Bit on the AS-i line input. If the slave was in
asynchronous state, it now transforms to
synchronous state. The Rec-Muxer is locked to the
AS-i line input until the next IC-reset. After the
generation of a REC-STRB signal the Control-Unit is
waiting for about 6.0 µs for the SEND-STRB to be
generated by the Main-State-Machine.
If the Control-Unit receives the active high SEND-
STRB signal (pulse width 500 ns), it starts the
transmission of the Send-Register data. Therefore,
the Send-Register data will be converted to an active
low Manchester II-coded (MAN) signal which is sent
to the AS-i line transmitter via SEND-D. The first
falling edge of the MAN signal occurs 11.75 µs
(Synchronous Mode) or 12.25 µs (Asynchronous
Mode) after the rising edge of the REC-STRB signal.
Hence, the delay from the rising edge of the End-Bit
of the master call (AS-i input) to the first falling edge
of the slave response (AS-i output) is 21.75 to
22.25 µs (Synchronous Mode) or 33.75 to 34.25 µs
(Asynchronous Mode).