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Data Sheet
687
Rev. 1.2, 2006-01-26
QuadFALC
TM
PEF 22554 E
Signaling Controller Operating Modes
Figure 130 HDLC Transmit Data Flow
Transmitting a HDLC frame via register CMDR.XTF (or CMDR2.XTF2/CMDR3.XTF3 for channel 2/3), the
address, the control fields and the data field have to be entered in the XFIFO (XFIFO2, XFIFO3).
If CCR2.XCRC (or CCR3.XCRC2/CCR4.XCRC3 for channel 2/3) is set, the CRC checksum will not be generated
internally. The checksum has to be provided via the transmit FIFO (XFIFO, XFIFO2, XFIFO3) as the last two bytes.
The transmitted frame is closed automatically with a closing flag only.
The QuadFALC
TM does not check whether the length of the frame, i.e. the number of bytes to be transmitted
makes sense or not.
12.2
Extended Transparent Mode
Characteristics: fully transparent
In no HDLC mode, fully transparent data transmission/reception without HDLC framing is performed, i.e. without
flag generation/recognition, CRC generation/check, or bit stuffing. This feature can be profitably used e.g. for:
Specific protocol variations
Transmission of a BOM frame (channel 1 only)
Test purposes
Data transmission is always performed out of the XFIFO (XFIFO2, XFIFO3). In transparent mode, the receive data
is shifted into the RFIFO (RFIFO2, RFIFO3).
Note: If a 1-byte frame is sent in extended transparent mode, in addition to interrupt ISR1.XPR (transmit pool
ready) the interrupt ISR1.XDU (transmit buffer underrun) is set and XFIFO is blocked.
12.3
Signaling Controller Functions
12.3.1
Transparent Transmission and Reception
When programmed in the extended transparent mode via the MODE registers (MODE.MDS(2:0) = 111
B,
MODE2.MDS2(2:0) = 111
B, MODE3.MDS3(2:0) = 111B), the QuadFALC
TM performs fully transparent data
transmission and reception without HDLC framing, i.e. without
Flag insertion and deletion
CRC generation and checking
Bit stuffing
In order to enable fully transparent data transfer, bit MODE.HRAC (MODE2.HRAC2, MODE3.HRAC3) has to be
set.
Received data is always shifted into RFIFO (RFIFO2, RFIFO3).
Data transmission is always performed out of XFIFO (XFIFO2, XFIFO3) by shifting the contents of XFIFO into the
outgoing data stream directly. Transmission is initiated by setting CMDR.XTF (04
H). A synchronization byte FFH
is sent automatically before the first byte of the XFIFO is transmitted.
CONTROL
(XHF)
Frame
HDLC
Transmit
ADDRESS
FLAG
XFIFO
ADDR
CTRL
FLAG
DATA
Ι
CHECKRAM
ITD06456
CRC