
67
7.3.2
VMEbus Interface
There is direct access to the 4-KByte Dual-Ported RAM area via the VMEbus
interface. The address range within the VMEbus address range is determined
by the configuration of the base address of the ES1650.1 Piggyback Carrier
Board.
7.3.3
Dual-Ported RAM Access
The data is transferred between the VMEbus and the PB1650PRT1.1 module
using a 2048 K x 16-bit Dual-Ported RAM memory.
Only 16-bit VMEbus accesses to the DPRAM are possible.
Only 32-bit accesses are admissible from the MPC555 to the 16-bit DPRAM
due to the different data bus access modes of MPC555 and VMEbus with 8-
bit, 16-bit and 32-bit accesses and an inconsistent connection of the 16-bit
Dual-Ported RAM component. The most significant 16 bits have an undefined
value in read operations and have to be masked out (e.g. with a logical ’AND’
with 0x0000FFFF). The relevant 16-bit words are on the VMEbus, which can
only make 16-bit accesses to the DPRAM, each at an interval of 32 bits, i.e.
only to even DPRAM addresses.
A standard storage interface from the VMEbus and MPC555 can be realized by
using C macros for 8-bit, 16-bit and 32-bit accesses.
DPRAM Address
MPC555 32-Bit Access
VME 16-Bit Access
0
Byte 0
Byte 0
1
Byte 1
Byte 1
2
Undef.
Undef.
3
Undef.
Undef.
4
Byte 2
Byte 2
5
Byte 3
Byte 3
6
Undef.
Undef.
7
Undef.
Undef.
...
...
...
Summary of Contents for ES1650.1
Page 1: ...ES1650 1 Piggyback Carrier Board User s Guide ...
Page 10: ...Introduction 10 ...
Page 20: ...20 Physical Dimensions Circuit board 100 x 160 mm Front panel Height 3 U Width 4 HP 20 3 mm ...
Page 45: ...45 Physical Dimensions Length 100 mm Width 48 mm Depth 12 mm ...
Page 46: ...46 ...
Page 64: ...PB1650PRT1 1 Prototyping Piggyback 64 ...
Page 82: ...82 ...