Memory Controller
MPC561/MPC563 Reference Manual, Rev. 1.2
10-14
Freescale Semiconductor
The CS
x
timing is defined by the setup time required between the address lines and the CE line. The
memory controller allows specification of the CS timing to meet the setup time required by the peripheral
device. This is accomplished through the ACS field in the base register. In
, the ACS bits are
set to 0b11, so CSx is asserted half a clock cycle after the address lines are valid.
Figure 10-10. Peripheral Devices Basic Timing (ACS = 11, TRLX = 0)
10.3.3
Relaxed Timing Examples
The TRLX field is provided for memory systems that need a more relaxed timing between signals. When
TRLX is set and ACS = 0b00, the memory controller inserts an additional cycle between address and
strobes (CS line and WE/OE).
When TRLX and CSNT are both set in a write to memory, the strobe lines (WE/BE[0:3] and CS, if ACS
= 0b00) are negated one clock earlier than in the regular case.
NOTE
In the case of a bank selected to work with external transfer acknowledge
(SETA = 1) and TRLX = 1, the memory controller does not support external
devices that provide TA to complete the transfer with zero wait states. The
minimum access duration in this case equals three clock cycles.
shows a read access with relaxed timing. Note the following:
•
Strobes (OE and CS) assertion time is delayed one clock relative to address (TRLX bit set effect).
•
Strobe (CS) is further delayed (half-clock) relative to address due to ACS field being set to 11.
CLOCK
Address
TS
TA
CS
RD/WR
Data
ACS = 11
CSNT = 1
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...