MPC555
/
MPC556
MEMORY CONTROLLER
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
10-7
wait states counter has expired, this assertion terminates the memory cycle. When
SETA is cleared, it is forbidden to assert external TA less than two clocks before the
wait states counter expires.
10.3.1 Memory Devices Interface Example
describes the basic connection between the MPC555 / MPC556 and a
static memory device. In this case CSx is connected directly to the chip enable (CE)
of the memory device. The WE/BE[0:3] lines are connected to the respective W in the
memory device where each WE/BE line corresponds to a different data byte.
Figure 10-5 MPC555
/ MPC556 GPCM–Memory Devices Interface
In
, the CSx timing is the same as that of the address lines output. The
strobes for the transaction are supplied by the OE and the WE/BE lines (if pro-
grammed as WE/BE). Because the ACS bits in the corresponding ORx register = 00,
CS is asserted at the same time that the address lines are valid. Note that because
CSNT is set, the WE signal is negated a quarter of a clock earlier than normal.
Memory
Address
CE
OE
W
Data
Address
CSx
OE
WE/BE
Data
MPC555 / MPC556
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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