CHAPTER 17 COMPACTFLASH CONTROLLER (ECU)
User’s Manual U14272EJ3V0UM
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17.4.5 CDSTCHGREG (Index: 0x04)
Bit
7
6
5
4
3
2
1
0
Name
Reserved
Reserved
Reserved
Reserved
CD_CHG
RDY_CHG
Reserved
BAT_DEAD
R/W
R
R
R
R
R/W
R/W
R
R/W
Reset
0
0
0
0
0
0
0
0
Bit
Name
Function
7 to 4
Reserved
0 is returned when read
3
CD_CHG
Card detect (CD1# and CD2# signals) status change
0 : Not changed
1 : Changed
2
RDY_CHG
Ready (CF_BUSY# signal) change
0 : No change or I/O card installed
1 : A low-to-high change has been detected indicating that the memory card
is ready to accept a new data transfer
1
Reserved
0 is returned when read
0
BAT_DEAD
Battery not usable or status change detection (CF_STSCHG# signal status)
0 : For memory cards, battery is good.
For I/O cards, the RI_EN bit of the ITGENCTREG register is set to 1,
or the CF_STSCHG# signal is at high level.
1 : For memory cards, a battery dead condition has been detected.
For I/O cards, the RI_EN bit of the ITGENCTREG register is cleared to 0 and
the CF_STSCHG# signal is at low level.
When this bit is set to 1, the system software then has to read the status change
register in the I/O card to determine the cause of STSCHG.
Caution CompactFlash cards do not support the BVD (battery status
detection) signal so that the BVD2/SPKR signal of the ECU is
internally fixed to low level.
This register indicates the source of the card status change interrupt request. Each source can be enabled to
generate this interrupt request by setting the corresponding bit in the CRDSTATREG register. The bits in this register
become 0 if their corresponding enable bits are cleared to 0.
If the EXWRBK bit is set to 1 in the GLOCTRLREG register, sources for the card status change interrupt request
is acknowledged when 1 is set to the CD_CHG bit in the CDSTCHGREG register though it has been already set to 1.
Once acknowledged, the CD_CHG bit is cleared to 0. The interrupt request signal caused by the card status change,
if any of the IRQ lines is enabled, remains active until all the bits in this register become 0.
If the EXWRBK bit is not set to 1, the card status change interrupt request, when any of the IRQ lines are enabled,
remains active until this register is read. In this mode, reading this register resets all status bits to 0, which has been
set to 1.