6-16
BajaPPC-750: VMEbus Interface
The CWT value of 2
15
PCI clock cycles determines how long to hold the VMEbus
after a coupled transaction (across the VMEbus) is made.
6.3.1 Addressing
The Universe can generate A16, A24, A32, and CR/CSR address phases on the
VMEbus in accordance with the VME64 specification (see control registers in
Section 6.2). Programming of the VME master (PCI slave) image determines the
address space, mode, and type. The Universe supports address pipelining, except
during MBLT cycles.
In addition, the USER_AM register allows for programming of two user-defined
address modifier codes (default=same as VME64 user-defined AM code). The
VMEbus decoding is such that the address must be in the window defined by the
base and bound addresses. The address modifier has to match one of those speci-
fied by the address space, mode, and type fields. The eight VME slave images are
bounded by A32 space. VME slave images 0 and 4 have a resolution of 4 kilo-
bytes. The other six VME slave images have a resolution of 64 kilobytes.
NOTE.
The address space of a VMEbus slave image must not overlap the Uni-
verse control and status registers. Also, slave image spaces must not
overlap each other, and master image spaces must not overlap each
other.
By default, the BajaPPC-750 NVRAM configuration parameters (see Chapter 10)
map one VMEbus master and two VMEbus slave images as indicated in the table
below:
The user can reconfigure this mapping to include up to four VMEbus master and
four VMEbus slave images. The mapping must be enabled via the
nvdisplay
and
nvupdate
monitor commands. Short VMEbus master space should be placed in
upper PCI I/O space.
CWT
Coupled window timer in PCI clocks.
This field no longer controls the Universe coupled window timer.
Instead, the Universe waits for 2
15
PCI clocks before giving up the VME-
bus. This timer restarts each time a PCI master tries a coupled request.
Changing the CWT values during a coupled cycled will produce unpre-
dictable results.
Table 6-3. VMEbus Default Memory Mapping
Type
Master Address Range (Hex)
Slave Base Address (Hex)
Extended C000,0000
– FCFF,FFFF
80000000
Standard BF00,0000
– BFFF,FFFF
200000
Short FEBF,0000
– FEBF,FFFF
1000
Содержание BajaPPC-750
Страница 2: ...BajaPPC 750 PowerPC Based Single Board Computer User s Manual May 2002...
Страница 4: ...BajaPPC 750 PowerPC Based Single Board Computer User s Manual May 2002...
Страница 7: ......
Страница 16: ...0002M621 15 ix Register Map 9 1 Counter Timer Status CTSR 9 2 Register Map 9 2 Counter Timer Mode CTMR 9 4...
Страница 19: ...xii BajaPPC 750 Contents...
Страница 57: ...3 12 BajaPPC 750 Central Processing Unit May 2002...
Страница 77: ...5 12 BajaPPC 750 PMC PCI Interface May 2002...
Страница 111: ...6 34 BajaPPC 750 VMEbus Interface May 2002...
Страница 135: ...8 18 BajaPPC 750 Serial and Parallel I O May 2002...
Страница 207: ...10 68 BajaPPC 750 Monitor May 2002...