peb20542 Infineon Technologies Corporation, peb20542 Datasheet - Page 112

• Manufacturer Part Number: peb20542
• Description: 2 Channel Serial Optimized Communication Controller With Dma
• Manufacturer: Infineon Technologies Corporation

PEB 20542
PEF 20542
Detailed Protocol Description
Transmission of Frames:
The SCC autonomously transmits S commands and S responses in the auto mode.
Either transparent or I-frames can be transmitted by the user. The software timer has to
be operated in the internal timer mode to transmit I-frames. After the frame has been
transmitted, the timer is self-started, the XFIFO is inhibited, and the SCC waits for the
arrival of a positive acknowledgement. This acknowledgement can be provided by
means of an S- or I-frame.
t
If no positive acknowledgement is received during time
, the SCC transmits an S-
1
command (p = ‘1’), which must be answered by an S-response (f = ‘1’). If the S-response
is not received, the process is performed n1 times (in HDLC known as N2, refer to
register TIMR3).
Upon the arrival of an acknowledgement or after the completion of this poll procedure
the XFIFO is enabled and an interrupt is generated. Interrupts may be triggered by the
following:
• message has been positively acknowledged (ALLS interrupt)
• message must be repeated (XMR interrupt)
• response has not been received (TIN interrupt).
In automode, only when the ALLS interrupt has been issued data of a new frame may
be provided to the XFIFO!
Upon arrival of an RNR frame, the software timer is started and the status of the remote
station is polled periodically after expiration of
t
, until the status ‘receive ready’ has been
1
detected. The user is informed via the appropriate interrupt. If no response is received
after n1 times, a TIN interrupt, and
t
clock periods thereafter an ALLS interrupt is
1
generated and the process is terminated.
Note: The internal timer mode should only be used in the auto mode.
Transparent frames can be transmitted in all operating modes.
Data Sheet
112
2000-09-14