BCM1250/BCM1125/BCM1125H
User Manual
10/21/02
B r o a d c o m C o r p o r a t i o n
Page
392
Section 12: PCMCIA Control Interface
Document
1250_1125-UM100CB-R
Selection of most of the parameters is straight forward. For reads the chip select width controls the cycle and
must be selected to be larger than the access time. In this case it is the tAcca(max) that controls this. The chip
select enables the address buffer, so the address only becomes valid after the output enable delay of the buffer
(5ns in this case).
The output disable time (tDis) sets the number of idle cycles. Assuming the next cycle is a write (i.e. the data
buffer will drive on the next IO_CS[6]) there are two cycles or 20ns belonging to the next cycle that can be part
of tDis (the cycle with IO_ALE asserted and the ale_to_cs delay), thus 30 ns or three cycles are needed in the
current access (tDis(part) on the diagram). There is always one idle cycle so idle_cycle must be set to 2 to give
the extra two idle cycles.
There are many parameters related to the write pulse. The controlling ones are the write width (tWP) which
directly requires the wr_width to be 8, and the address to write deassertion setup time (tSUaweh). Fortunately
once these are set the data hold time is satisfied with the same chip select width as for the read.
U
SING
THE
P
OWER
O
UTPUTS
If the PCMCIA mode is not enabled by the reset time configuration resistor then the three power control lines
can be controlled by software directly through the
pcmcia_cfg
register.
If the pcmcia_cfg_pwr_ctl bit is set then the state of the GPIO[12] and GPIO[13] pins are used in the same way
they would be (as CD1# and CD2#) in PCMCIA mode. They must be low to allow software to set the power
control output lines, and the bits in the
pcmcia_cfg
bits will be cleared if either goes high. This may be used
in systems other than PCMCIA that need to implement hot-swap logic. The pins remain GPIO pins, if they are
configured as outputs then the value being driven will be read back from the pin and used to control the power
logic.
and
show the logic of the power control lines when PCMCIA
mode is disabled.
Table 272: Example Generic Bus Timing parameters
Parameter
Value
ale_width
1
ale_to_cs
1
cs_width
17
cs_to_oe
0
oe_to_cs
0
ale_to_wr
8
wr_width
8
idle_cycel
2
Содержание BCM1125
Страница 18: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page xviii Document 1250_1125 UM100CB R ...
Страница 28: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page xxviii Document 1250_1125 UM100CB R ...
Страница 515: ...BCM1250 BCM1125 BCM1125H User Manual 10 21 02 Broadcom Corporation Page vii Index Document 1250_1125 UM100CB R ...