pef20550 Infineon Technologies Corporation, pef20550 Datasheet - Page 63

• Manufacturer Part Number: pef20550
• Description: Extended Line Card Interface Controller Elic
• Manufacturer: Infineon Technologies Corporation

Receive Direction
In auto-mode the SACCO provides address recognition for 2- and 1-byte address fields.
The auto-mode protocol is only applied when RAL1 respectively RAH1/RAL1 match.
With any other matching combination, the frame is transferred transparently into the
RFIFO and an interrupt (RPF or RME) is issued.
If no address match occurs, the frame is skipped. The auto-mode protocol processes
RR- and I-frames automatically. On the reception of any other frame type an EHC-
interrupt (extended HDLC frame) is generated. No data is stored in the RFIFO but due
to the internal hardware structure the HDLC-control field is temporarily stored in register
RHCR. In the PBC-protocol an extended HDLC-frame does not contain any data.
Table 10
HDLC-Control Field in Auto-mode
HDLC-Control Byte
xxxP xxx0
xxxP xx01
xxxx xx11
RR-frames
RR-frames are processed automatically and are not stored in RFIFO.
When a RR-frame with poll bit set (control field = xxx10001) is received, it is interpreted
as a request to transmit direct data.
Depending on the status of the XFIFO an I-frame (data available) or a RR-response (no
data available) is issued.
This behavior guarantees minimum response times and supports a fast cyclical polling
of signaling data in a point-to-multi-point configuration.
A RR-frame with poll bit = 0 is interpreted as an acknowledgment for a previously
transmitted I-frame: the XFIFO is cleared, a XPR interrupt is emitted, no response is
generated.
The polling of a frame can be repeated an unlimited number of times until the frame is
acknowledged. Depending on the status of the bit MODE:AREP (auto repeat), the
transmission is repeated without or with the intervention of the CPU (XMR interrupt).
The auto repeat mode must not be selected, when the frame length exceeds 32 bytes.
In DMA mode, when using the auto repeat mode, the control response will not be
compatible to the PBC.
Semiconductor Group
Frame Type
I-frame
RR-frame
Extended HDLC-frame
63
Functional Description
PEB 20550
PEF 20550
01.96