Memory Controller
MPC885 PowerQUICC Family Reference Manual, Rev. 2
15-32
Freescale Semiconductor
Note also the following:
•
Address incrementing is not provided in this mode. Addresses driven by the MPC885 remain the
same throughout the cycle.
•
The external slave must provide TA for all beats of the burst.
15.6
User-Programmable Machines (UPMs)
The two user-programmable machines (UPMs) are flexible interfaces that connect to a wide range of
memory devices. At the heart of each UPM is an internal-memory RAM array that specifies the logical
value driven on the external memory controller pins for a given clock cycle. Each word in the RAM array
provides bits that allow a memory access to be controlled with a resolution of one quarter of the external
bus clock period on the byte-select and chip-select lines.
Figure 15-31
shows the basic operation of each
UPM. The following events initiate a UPM cycle:
•
Any internal or external master requests an external memory access to an address space mapped to
a chip-select serviced by the UPM
•
A UPM periodic timer expires and requests a transaction, such as a DRAM refresh
•
A transfer error or reset generates an exception request
•
The MCR receives a
RUN
command from the CPU
Figure 15-31. User-Programmable Machine Block Diagram
The RAM array contains 64 32-bit RAM words. The signal timing generator loads the RAM word from
the RAM array to drive the general-purpose lines, byte-selects, and chip-selects. If the UPM reads a RAM
word with WAEN set, the external UPWAIT signal is sampled and synchronized by the memory controller
and the current request is frozen (if and while UPWAIT remains asserted).
MCR
RUN
command
UPM Periodic
Timer Request
Array
Index
Generator
Internal/External
Memory Access Request
Exception Request
Index
Signals
Timing
Generator
Internal
Signals
Latch
Wait
Request
Logic
RAM Array
UPWAIT
WAEN Bit
Internal Controls
GPL
x
, BS_
x
, CS
x
Increment
Index
(LAST = 0)
Hold
(issued in software)
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...