Functional Description
MEN Mikro Elektronik GmbH
57
20A014-00 E2 – 2007-08-16
2.16.6
Slot-1 Function
The slot-1 function is auto-detected. It can be read from the
SYSCTL register
(bit
SYSCON
). The A14C samples
BG3IN
# after
SYSRES#
has gone high. As specified
in the VMEbus specification all
BG
lines should be high after reset. Therefore only
in slot 1
/BG3IN
can be sampled low, due to a local pull-down resistor.
After slot 1 is detected the functions listed below are enabled.
• Generation of
SYSRES#
• Generation of
SYSCLK
(not provided during slot 1 detection cycle)
• Level 3 arbitration
• Bus arbitration timeout 250 µs
• Bus transfer timeout 125 µs
The timeouts cannot be changed.
SYSCTL – System Controller Register (
0x0018
) (read/write)
7..3
2
1
0
-
ATO
SYSRES
SYSCON
ATO
Monitor for arbitration timeout signal (read only)
0 =
1 =
No arbitration timeout (default)
Arbitration timeout occurred
SYSRES
Reset VMEbus; generates
SYSRES#
on the VMEbus
0 =
1 =
SYSRES#
not active
SYSRES#
active
SYSCON
System controller status (depends on slot 1 auto-detection after reset).
May be overridden by software.
0 =
1 =
Slot 1 function disabled
Slot 1 function enabled
