User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 12: PCMCIA Control Interface Page
383
S e c t i o n 1 2 : P C M C I A C o n t r o l I n t e r f a c e
I
NTRODUCTION
The part provides limited support for using PCMCIA memory cards attached to the generic bus. The interface
allows card insertion and removal to be detected, provides and removes power from the card, and allows
reading and writing of memory and attribute space on the card. The interface does not directly support I/O
cards.
The standard was renamed in 1995, so PCMCIA cards are more correctly know as 16-bit PC Cards. Since the
interface discussed in this section refers only to the cards defined in the PCMCIA Standard Release 2.1 the
more popular name PCMCIA is used in this document.
The PCMCIA interface connects as chip select region 6 on the generic bus (see
). The generic bus configuration registers are used to set the address mapping and
access timing for the card. The additional control logic provides:
•
The two card enable signals (CE1# and CE2#) required by a card with a 16 bit data path.
•
Detection of card insertion and removal (CD1# and CD2#), the VCC voltage requested by the card (VS1#
and VS2#), card READY, and write protect state (WP).
•
Software control of the PCMCIA REG# signal to select between accessing regular memory and attribute
memory, and the card RESET signal.
•
Outputs to control a supply of VCC and VPP to the card. VCC can either be controlled from software or
automatically. Power is automatically removed when the card is removed.
•
Interrupts raised to report card status changes.
C
ONNECTING
A
PCMCIA S
LOT
The PCMCIA interface uses ten of the GPIO pins to provide the additional support signals. In addition there
are three dedicated pins that provide the card power enables (see
for information on using these pins as general outputs if PCMCIA is not used). The
reset-time configuration resistor on generic address bit IO_AD[16] must pull high to convert the GPIO[15:6]
pins to PCMCIA use. For proper operation the
gpio_input_invert
register bits [15:6] must be left as zeros
(their default state) to disable the input inverter on the PCMCIA pins. Operation of the PCMCIA card is
UNDEFINED if any of these bits are set, and if the voltage sense inputs are inverted the wrong VCC voltage
could be supplied to the card.