16-4
MPC850 Integrated Communications Microprocessor Users Manual
MOTOROLA
Part IV. The Hardware Interface
16.2.2 PCMCIA Input Port Signals
The following signals are used by a PCMCIA slot to indicate card status. The MPC850
provides synchronization, transition detection, optional interrupt generation, and the means
for the software to read the signal state. This function is not necessarily speciTc to
PCMCIA; a system can use these signals as a general-purpose input port with edge
detection and interrupt capability. These signals appear on pins IP_B[0D7]. All these signals
are symmetrical except IP_B7, which has extended edge detection capability and IP_B2,
which serves as an IOIS16_B cycle-control signal for PCMCIA cycles.
16.2.3 PCMCIA Output Port Signals (OP[0D4])
A PCMCIA slot can use the signals in Table 16-3 to control the RESET input and output
enable of the buffers to the card. The MPC850 gives software a way to control the output
signal state. This function is not necessarily speciTc to the PCMCIA interface; a system can
Table 16-2. PCMCIA Input Port Signals
Signal
Description
VS1_B,
VS2_B
Voltage sense. Input. Used as VS1 and VS2 and generated by PC cards. They notify the socket of the card
V
CC
requirement. These signals are connected to IP_B[0D1].
WP
Write protect. Input. When the card and socket are programmed for memory interface operation, this
signal is used as WP. It reects the state of the write-protect switch on the PC card. The PC card must
assert WP when the card switch is enabled. It must be negated when the switch is disabled. For a PC card
that is writable without a switch, WP must be connected to ground. If the PC card is permanently
write-protected, WP must be connected to V
CC
. These signals are connected to IP_B2 pins.
CD1_B,
CD2_B
Card detect. Input. Provide proper detection of card insertion. They must be connected to ground internally
on the PC card, thus, these signals are forced low when a card is placed in the socket. These signals must
be pulled up to system V
CC
to allow card detection to function while the card socket is powered down.
These signals are connected IP_B4 and IP_B3, respectively.
BVD1_B,
BVD2_B
Battery voltage detect. Input. When the card and its socket are programmed for memory interface
operation, these signals are used as BVD1_B and BVD2_B and are generated by PC cards with on-board
batteries to report the battery condition. Both BVD1_B and BVD2_B must be held asserted when the
battery is in good condition. Negating BVD2_B while keeping BVD1_B asserted indicates the battery is in
a warning condition and should be replaced, although data integrity on the card is still assured. Negating
BVD1_B indicates that the battery is no longer serviceable and data is lost, regardless of the state of
BVD2_B. These signals are connected to IP_B6 and IP_B5, respectively.
STSCHG_B Status change. Input. When the card and its socket are programmed for I/O interface operation, BVD1_B
is used as STSCHG_B and is generated by I/O PC cards. STSCHG_B must be held negated when the
òsignal on changeó bit and òchangedó bit in the card status register on the PC card are either or both zero.
STSCHG_B must be asserted when both bits = 1.
SPKR_B
Speaker. input. When the card and socket are programmed for I/O interface operation, BVD2_B is used as
digital audio (SPKR_B) and is generated by I/O PC cards. SPKR_B must be used to provide the sockets
single amplitude (digital) audio wave form to the system. The SPKR_B signal is routed through the
speaker out signal (SPKROUT).
RDY/
BSY_B,
IREQ_B
Ready/busy or interrupt request. 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 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 interface operation, this signal is used as IREQ_B and must be asserted by a PC card to indicate
that a device on the PC card requires service by host software. Must be held negated when no interrupt is
requested. These signals are connected to IP_B7.