PCMCIA Interface
17-6
MPC823e REFERENCE MANUAL
MOTOROLA
PCMCIA INTERFACE
17
• Speaker (SPKR
)—Input. When the card and its socket are programmed for I/O
interface operation, the BVD2_B signal is used as SPKR
and it is generated by the I/O
PC cards. The SPKR
signal must be used to provide the socket’s single amplitude
(digital) audio waveform to the system. The SPKR
signal is routed out the SPKROUT
signal if the card and its socket are programmed for I/O interface operation.
• Ready/Busy/Interrupt Request (RDY/BSY_B/IREQ_B)—Input. When the card and its
socket are programmed for memory interface operation, this signal is used as RDY/
BSY_B and must be asserted low by a PC card to indicate that the PC card is busy
processing a previous
WRITE
command. When the card and its socket are
programmed for I/O operation, this signal is used as IREQ_B
and must be asserted low
to generate an interrupt. This signal must be set high when no interrupt is requested.
This signal is connected to the IP_B7 pin.
17.3.3 The PCMCIA Output Port Signals
The following signals are used by a PCMCIA slot to control the RESET
signal to the card
and the output enable of the buffers to the card. The MPC823e allows software to control
the output signal state. This function is not necessarily specific to the PCMCIA interface and
these signals, which appear on the OP[2:3] pins, may be used by a system as a general-
purpose output port. The OP[2:3] pins, when they are not operating the PCMCIA controller,
can be accessed as general-purpose outputs through the CBOE and CBRESET bits of the
PGCRB register.
• Card Reset (RESET_B)—Output. This signal is provided to clear the card configuration
option register residing on the card, thus placing the card in its default (memory-only
interface) state and initiating the beginning of any additional card initialization.
RESET_B is connected to the OP3 pin.
• PCMCIA Buffers Output Enable (POE_B
)—Output. This line is an output port line
reflecting the value of the CBOE bit in the PCMCIA interface power control register. It
must be used to three-state the address and strobe pins addressing the slot. POE_B
is
connected to the OP2 pin.
17.3.4 Other PCMCIA Signals
The following special function signals can be used by the PCMCIA socket or by the system
for other purposes.
• Power Is On (IRQ
)—Input. One IRQ signal provided for general-purpose interrupt
requests may be used by the card power supply circuitry to notify the MPC823e
processor when the power supply to the card has reached the required voltage.
• Speaker Out (SPKROUT)—Output. This signal is used to provide a digital audio
waveform that is to be driven to the system’s speaker. It is generated from the SPKR
input port signal exclusive-Or’ed with the output from Timer 1. See
Section 16.4.2 Timer Operation
for more information.
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