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74
7.4
Status Register
The status register provides status over the PCI4515 interface to the PCI bus. All bit functions adhere to the definitions
in the
PCI Local Bus Specification
, as seen in the following bit descriptions. See Table 73 for a complete description
of the register contents.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Name
Status
Type
RCU
RCU
RCU
RCU
RCU
R
R
RCU
R
R
R
R
RU
R
R
R
Default
0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
0
Register:
Offset:
Type:
Default:
Status
06h
Read/Clear/Update, Read-only
0210h
Table 73. Status Register Description
BIT
FIELD NAME
TYPE
DESCRIPTION
15
PAR_ERR
RCU
Detected parity error. Bit 15 is set to 1 when either an address parity or data parity error is detected.
14
SYS_ERR
RCU
Signaled system error. Bit 14 is set to 1 when SERR is enabled and the PCI4515 controller has signaled
a system error to the host.
13
MABORT
RCU
Received master abort. Bit 13 is set to 1 when a cycle initiated by the PCI4515 controller on the PCI
bus has been terminated by a master abort.
12
TABORT_REC
RCU
Received target abort. Bit 12 is set to 1 when a cycle initiated by the PCI4515 controller on the PCI
bus was terminated by a target abort.
11
TABORT_SIG
RCU
Signaled target abort. Bit 11 is set to 1 by the PCI4515 controller when it terminates a transaction on
the PCI bus with a target abort.
109
PCI_SPEED
R
DEVSEL timing. Bits 10 and 9 encode the timing of DEVSEL and are hardwired to 01b, indicating that
the PCI4515 controller asserts this signal at a medium speed on nonconfiguration cycle accesses.
8
DATAPAR
RCU
Data parity error detected. Bit 8 is set to 1 when the following conditions have been met:
a. PERR was asserted by any PCI device including the PCI4515 controller.
b. The PCI4515 controller was the bus master during the data parity error.
c. Bit 6 (PERR_EN) in the command register at offset 04h in the PCI configuration space
(see Section 7.3) is set to 1.
7
FBB_CAP
R
Fast back-to-back capable. The PCI4515 controller cannot accept fast back-to-back transactions;
therefore, bit 7 is hardwired to 0.
6
UDF
R
User-definable features (UDF) supported. The PCI4515 controller does not support the UDF;
therefore, bit 6 is hardwired to 0.
5
66MHZ
R
66-MHz capable. The PCI4515 controller operates at a maximum PCLK frequency of 33 MHz;
therefore, bit 5 is hardwired to 0.
4
CAPLIST
R
Capabilities list. Bit 4 returns 1 when read, indicating that capabilities additional to standard PCI are
implemented. The linked list of PCI power-management capabilities is implemented in this function.
3
INT_STATUS
RU
Interrupt status. This bit reflects the interrupt status of the function. Only when bit 10 (INT_DISABLE)
in the command register (see Section 7.3) is a 0 and this bit is 1, is the function’s INTx signal asserted.
Setting the INT_DISABLE bit to 1 has no effect on the state of this bit.
20
RSVD
R
Reserved. Bits 30 return 0s when read.