SAB 82525
SAB 82526
SAF 82525
SAF 82526
CTS Signal Clock Mode 5
In clock mode 5 the CTS signal is evaluated not only in the time-slot "window", but also
between the time-slot "windows". CTS must not be disabled during the transmission of a
frame. Even between the time-slot "windows" CTS has to be active until the transmission of
the frame has been completed. Thus, CTS cannot be used to select/deselect particular time-
slot "windows" for HSCX.
Note: In the case where permission to transmit is not required, the CTSA/CTSB inputs can be
connected directly to VSS.
Additionally, any state transition on the CTS input pin will generate an interrupt indicated via
the EXIR register, if this function is enabled by setting the CIE bit in the CCR2 register.
T xCLK
T xD
RTS
CTS
Sampling
ITT00244
Figure 31
RTS-CTS Handshaking
Carrier Detect (CD) Receiver Control
Similar to the RTS/CTS control for the transmitter, the HSCX supports the carrier detect
modem control function for the serial receivers, if the Carrier Detect Auto Start (CAS) function
is programmed setting the CAS bit in the XBCH register. This function is always available in
clock modes 0, 2, 3 via the A×CLK pin, and in clock modes 4, 6, 7 via the T× CLK pin only if it
has been programmed as input clearing the TIO bit in the CCR2 register. In clock mode 1 the
CD function is not supported (see table 6 for an overview).
If the CAS function is selected, the respective HDLC receiver is enabled and data reception is
started when an high level is sampled at the CD input.
Semiconductor Group
64
SIEMENS [ Siemens Semiconductor Group ]
