VXI SM8000 - Manual (Page 37)

VXI Technology, Inc.
SM8000 Series Programming 37
S
ECTION
4
P
ROGRAMMING
R EGISTER A CCESS
The SMIP II optical modules are VXIbus register-based devices. Register-based programming is a
series of reads and writes directly to the switch module registers. This eliminates the time for
command parsing thus increasing speed.
A DDRESSING
The VTI switching modules utilize either the A24 or A32 space of the shared-memory
architecture. To read or write to a module register, a register address needs to be specified. This is
done by using the offset value (assigned by the resource manager) and multiplying it by 256 or 64
k to get the base address in A24 or A32 address space, respectively
A24 Base Address = Offset value * 0x00FF (or 256)
A32 Base Address = Offset value * 0xFFFF (or 65,535)
The A24 or A32 offset value, assigned by the resource manager, can also be accessed by reading
the A16 Offset Register. To address the A16 Offset Register use the following formula:
A16 Base Address = (Logical Address * 64) + 0xC000 (or 49,152)
then
A16 Offset Register Address = A16 Base Address + 6
See following for the A16 Memory Map and the A24/A32 address space allocation.