Signal Pins
Table 2-2 Signal and Package Information for the 160-Pin LQFP and MBGA
Signal
Name
WR
Pin
No.
51
Ball No.
Type
State
During
Reset
Signal Description
L4
Output
Tri-stated
Write Enable
鈥?WR is asserted during external memory write cycles.
When WR is asserted low, pins D0 - D15 become outputs and the
device puts data on the bus. When WR is deasserted high, the
external data is latched inside the external device. When WR is
asserted, it qualifies the A0 - A23, PS, DS, and CSn pins. WR can be
connected directly to the WE pin of a static RAM.
Depending upon the state of the DRV bit in the EMI bus control register
(BCR), WR is tri-stated when the external bus is inactive.
Most designs will want to change the DRV state to DRV = 1 instead of
using the default setting.
To deactivate the internal pull-up resistor, set the CTRL bit in the
SIM_PUDR register.
PS
(CS0)
53
N6
Output
Tri-stated
Program Memory Select
鈥?This signal is actually CS0 in the EMI,
which is programmed at reset for compatibility with the 56F80x PS
signal. PS is asserted low for external program memory access.
Depending upon the state of the DRV bit in the EMI bus control register
(BCR), CS0 is tri-stated when the external bus is inactive.
CS0 resets to provide the PS function as defined on the 56F80x
devices.
(GPIOD8)
Input/
Output
Input
Port D GPIO
鈥?This GPIO pin can be individually programmed as an
input or output pin.
To deactivate the internal pull-up resistor, clear bit 8 in the
GPIOD_PUR register.
DS
(CS1)
54
L5
Outpu
Tri-stated
Data Memory Select
鈥?This signal is actually CS1 in the EMI, which
is programmed at reset for compatibility with the 56F80x DS signal. DS
is asserted low for external data memory access.
Depending upon the state of the DRV bit in the EMI bus control register
(BCR), CS1 is tri-stated when the external bus is inactive.
CS1 resets to provide the DS function as defined on the 56F80x
devices.
(GPIOD9)
Input/
Outputt
Input
Port D GPIO
鈥?This GPIO pin can be individually programmed as an
input or output pin.
To deactivate the internal pull-up resistor, clear bit 9 in the
GPIOD_PUR register.
56F8367 Technical Data, Rev. 3.0
Freescale Semiconductor
Preliminary
25