
ExCA Compatibilty Registers (Function 0)
114
September 2005
SCPS110
5.5
ExCA Card Status-Change Register
The ExCA card status-change register controls interrupt routing for I/O interrupts as well as other critical 16-bit
PC Card functions. The register enables these interrupt sources to generate an interrupt to the host. When
the interrupt source is disabled, the corresponding bit in this register always reads 0b. When an interrupt
source is enabled, the corresponding bit in this register is set to indicate that the interrupt source is active. After
generating the interrupt to the host, the interrupt service routine must read this register to determine the source
of the interrupt. The interrupt service routine is responsible for resetting the bits in this register as well.
Resetting a bit is accomplished by one of two methods: a read of this register or an explicit writeback of 1b
to the status bit. The choice of these two methods is based on bit 2 (interrupt flag clear mode select) in the
ExCA global control register (CB offset 81Eh, see Section 5.20). See Table 57 for a complete description
of the register contents.
ExCA register offset:
CardBus socket address + 804h;
Card A ExCA offset 04h
Register type:
Read-only
Default value:
00h
BIT NUMBER
7
6
5
4
3
2
1
0
RESET STATE
0
Table 57. ExCA Card Status-Change Register Description
BIT
SIGNAL
TYPE
FUNCTION
74
RSVD
R
Reserved. Bits 74 return 0h when read.
3
CDCHANGE
R
Card detect change. Bit 3 indicates whether a change on CD1 or CD2 occurred at the PC Card
interface. This bit is encoded as:
0 = No change detected on either CD1 or CD2
1 = Change detected on either CD1 or CD2
2
READYCHANGE
R
Ready change. When a 16-bit memory is installed in the socket, bit 2 includes whether the source of
a PCIxx12 interrupt was due to a change on READY at the PC Card interface, indicating that the
PC Card is now ready to accept new data. This bit is encoded as:
0 = No low-to-high transition detected on READY (default)
1 = Detected low-to-high transition on READY
When a 16-bit I/O card is installed, bit 2 is always 0b.
1
BATWARN
R
Battery warning change. When a 16-bit memory card is installed in the socket, bit 1 indicates whether
the source of a PCIxx12 interrupt was due to a battery-low warning condition. This bit is encoded as:
0 = No battery warning condition (default)
1 = Detected battery warning condition
When a 16-bit I/O card is installed, bit 1 is always 0b.
0
BATDEAD
R
Battery dead or status change. When a 16-bit memory card is installed in the socket, bit 0 indicates
whether the source of a PCIxx12 interrupt was due to a battery dead condition. This bit is encoded as:
0 = STSCHG deasserted (default)
1 = STSCHG asserted
Ring indicate. When the PCIxx12 is configured for ring indicate operation, bit 0 indicates the status of
RI.
These are PME context bits and can be cleared only by the assertion of GRST when PME is enabled. If PME is not enabled, then these bits are
cleared by the assertion of PRST or GRST.