pef82902 Infineon Technologies Corporation, pef82902 Datasheet - Page 119

• Manufacturer Part Number: pef82902
• Description: 4b3t Second Generation Modular Isdn Nt Intelligent Extended
• Manufacturer: Infineon Technologies Corporation

– XPR (Transmit Pool Ready) interrupt, indicating that a data block of up to 16 or 32
– XDU (Transmit Data Underrun) interrupt, indicating that the transmission of the
– XMR (Transmit Message Repeat) interrupt, indicating that the transmission of the
Three different control commands are used for transmission of data:
– XTF (Transmit Transparent Frame) command, telling the T-SMINT
– XME (Transmit Message End) command, telling the T-SMINT
– XRES (Transmitter Reset) command, resetting the HDLC transmitter and clearing the
Optionally two additional status conditions can be read by the host:
– XDOV (Transmit Data Overflow), indicating that the data block size has been
– XFW (Transmit FIFO Write Enable), indicating that data can be written to the XFIFO.
Note: The significant interrupts and commands are underlined as only these are usually
Data Sheet
bytes (block size selected via EXMR:XFBS) can be written to the XFIFO.
A XPR interrupt is generated either
– after a XRES (Transmitter Reset) command (which is issued for example for frame
– when a data block from the XFIFO is transmitted and the corresponding FIFO
current frame has been aborted (seven consecutive ’1’s are transmitted) as the XFIFO
holds no further transmit data. This occurs if the host fails to respond to a XPR
interrupt quick enough.
complete last frame has to be repeated as a collision on the S bus has been detected
while the first data bytes have already been overwritten with new data. So the XFIFO
does not hold the first data bytes of the frame (the HDLC transmitter is stopped if a
collision on the S bus has been detected).
The occurrence of a XDU or XMR interrupt clears the XFIFO and a XPR interrupt is
issued together with a XDU or XMR interrupt, respectively. Data cannot be written to
the XFIFO as long as a XDU/XMR interrupt is pending.
or 32 bytes (according to selected block size) have been written to the XFIFO and
should be transmitted. A start flag is generated automatically.
block written to the XFIFO completes the corresponding frame and should be
transmitted. This implies that according to the selected mode a frame end (CRC +
closing flag) is generated and appended to the frame.
transmit FIFO of any data. After a XRES command the transmitter always sends an
abort sequence, i.e. this command can be used to abort a transmission. XRES does
not clear pending interrupt indications of the transmitter, but has to be be cleared by
reading these interrupts.
exceeded, i.e. more than 16 or 32 bytes were entered and data was overwritten.
This status flag may be polled instead of or in addition to XPR.
abort) or
space is released to accept further data from the host.
used during a normal transmission sequence.
105
Functional Description
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IX that the last data
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IX that up to 16
PEF 81902
2001-11-12