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
385
Since the interface inputs are 3.3V only, care must be taken to buffer inputs from the card if 5V cards need to
be supported. A FET switch or translating buffer can be used to provide the voltage conversion from card
outputs and to provide power-down isolation for card inputs
.
The card detect and voltage sense lines are only
statically pulled down or not connected on the card, they do not need buffers but should be pulled up to 3.3V
on the main board.
The PCMCIA card uses two card enable signals (CE1# and CE2#) to indicate which byte lane is being used
in a transfer. The PCMCIA control logic generates these from IO_CE_L[6] based on the size of the transfer
requested by the CPU and the data width that the cs6 region has been configured for. If the interface is 2 bytes
wide then the bottom address bit is not used by the card and the card enable lines select which byte lane is
used during byte accesses. If the interface is only 1 byte wide then PC_CE1_L is always used with the lowest
address bit, and PC_CE2_L is never asserted.
The PC_REG_L signal is used to select between accesses to attribute memory (REG# low on the card) and
regular memory. It is entirely under software control. The PC_RESET signal is asserted to reset the card, while
the card is in place it is controlled by software but the signal (and corresponding bit in the
pcmcia_cfg
configuration register) will be set high when there is no card detected.
The WP (write protect) and READY status signals from the card are monitored and made available to software.
Each of these signals has a transition detector and can raise the pcmcia_interrupt when they change. These
signals have a 60ns glitch filter.
The VS1# and VS2# voltage sense signals are monitored and made available to software, they have a 60ns
glitch filter. These lines are static signals from the card, and are either not connected or passively pulled low
on the card. They indicate the VCC that the socket requests when it is first powered up.
The PCMCIA card detect lines (CD1# and CD2#) are monitored by the hardware. A card is only considered
inserted when these two signals are both low (physically these are near the two ends of the card socket and
have shorter pins so they are the last pins to make contact). These signals have a 1 ms glitch filter. The
(internal) card detect signal is the NOR of the filtered version of these signals. The pcmcia_interrupt can be
raised when the card detect status changes.
There are three dedicated outputs used to enable power to the card. Two of these (PC_EN3V and PC_EN5V)
control VCC, and the third (PC_ENVPP) controls the VPP programming voltage. The power enable signals are
forced to be deasserted when the two card detect signals indicate a card is removed or not present. This
provides the auto power down feature when a card is extracted.
Table 268: Source for PCMCIA Card Enable Signals
io_width_sel configuration
Access Size
PC_CE1_L
(data on IO_AD[31:24])
PC_CE2_L
(data on IO_AD[23:16])
00 - 1 bytes
any
IO_CS_L[6]
1
01 - 2 bytes
even byte
IO_CS_L[6]
1
01 - 2 bytes
odd byte
1
IO_CS_L[6]
01 - 2 bytes
Half -word
IO_CS_L[6]
IO_CS_L[6]