Pcmcia Output Port Signals (Op[0–4]); Other Pcmcia Signals; Operation Description - Freescale Semiconductor MPC850 User Manual

Table 16-2. PCMCIA Input Port Signals (Continued)
Signal
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 socket's
single amplitude (digital) audio wave form to the system. The SPKR_B signal is routed through the
speaker out signal (SPKROUT).
RDY/ BSY_B, Ready/busy or interrupt request. Input. When the card and its socket are programmed for memory
IREQ_B 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.
16.2.3 PCMCIA Output Port Signals (OP[0–4])
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 specific to the PCMCIA interface; a system can
use these signals as a general-purpose output port.
Signal
RESET_B Card reset. Output. Provided to clear the card's configuration option register, thus placing the card in its
default (memory-only interface) state and beginning an additional card initialization. RESET_B is
connected to OP3.
POE_B PCMCIA buffers output enable. An output port line reflecting the value of PGCRB[CBOE]. Used to
three-state address and strobe lines addressing each slot. POE_B connects to OP2.

16.2.4 Other PCMCIA Signals

The PCMCIA socket uses the signals in Table 16-4, although their function is not
necessarily specific to PCMCIA.
Signal
IRQ Power is on. Input. The card power supply circuitry can use an IRQ signal as a general-purpose interrupt
request to notify the MPC850 when the card's power supply reaches the full required voltage.
SPKROUT Speaker out. Output. Provides a digital audio wave form to be driven to the system's speaker. It is
generated as the SPKR_B input signal.
Note: General purpose timer 1 can be used to drive SPKROUT. When enabled, timer 1 is exclusive
ORed with the SPKR_B input signal to generate SPKROUT. See Section 17.2.2.6, "Timer 1 and
SPKROUT."

16.3 Operation Description

This section describes the operation of memory and I/O cards, interrupt detection and
handling, power control, and reset.
Table 16-3. PCMCIA Output Port Signals
Table 16-4. Other PCMCIA Signals
Chapter 16. PCMCIA Interface
Description
Description
Description
Operation Description