Processor Users Manual

27-20 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
Table 27-14 describes interrupt circular table Þelds.
Bits 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Field V W Ñ UN TXB Ñ NID IDL MRF RXF BSY RXB
R/W R/W
Bits 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Field Ñ Channel Number 0 0 0 0 0 0
R/W R/W
Figure 27-14. Interrupt Circular Table Entry
Table 27-14. Interrupt Circular Table Entry Field Descriptions
Bits Name Description
0 V Valid bit. V = 1 indicates that this entry contains valid interrupt information. Upon generating a new
entry, the CP sets V = 1. The user clears V immediately after it reads the interrupt ßags of the entry
(before processing the interrupt). The V bits in the table are user-initialized. During initialization, the
user must clear those bits in all table entries.
1 W Wrap bit. W = 1 indicates the last interrupt circular table entry. The next eventÕs entry is written/read
(by CP/user) from the address contained in INTBASE (see Table 27-1). During initialization, the user
must clear all W bits in the table except for the last one which must be set.
2Ð5 Ñ Reserved, should be cleared.
6 UN Tx no data. The CP sets this ßag if there is no data available to be sent to the transmitter. The
transmitter sends an ABORT indication and then sends idles.
7 TXB Tx buffer. A buffer has been completely transmitted. TXB is set (and an interrupt request is
generated) as soon as the programmed number of PAD characters (or the closing ßag, for PAD = 0)
is written to MCC transmit FIFO. This controls when the TXB interrupt is given in relation to the
closing ßag sent out at TXD. Section 27.11.2, ÒTransmit Buffer Descriptor (TxBD)Ó describes how
PAD characters are used.
8Ð9 Ñ Reserved, should be cleared.
10 MRF Maximum receive frame length violation. This interrupt occurs in HDLC mode when more bytes are
received than the value speciÞed in MFLR. This interrupt is generated as soon as the MFLR value is
exceeded; the remainder of the frame is discarded
11 NID Set whenever a pattern that is not an idle pattern is identiÞed.
12 IDL Idle. Set when the channelÕs receiver identiÞes the Þrst occurrence of HDLC idle (0xFFFE) after any
non-idle pattern.
13 RXF Rx frame. A complete HDLC frame has been received.
14 BSY Busy. A frame was received but was discarded due to lack of buffers.
15 RXB Rx buffer. A buffer has been received on this channel that was not the last buffer in frame. This
interrupt is also given for different error types that can happen during reception. Error conditions are
reported in the RxBD.
16Ð18 Ñ Reserved, should be cleared.
19Ð26 CN Channel number. IdentiÞes the requests channel index (0Ð255).
27Ð31 Ñ Reserved, should be cleared.