Dmac Ton/Toff Timers And Vmebus Global Time-Out Control Register - Motorola MVME162FX Programmer's Reference Manual

DMAC Ton/Toff Timers and VMEbus Global Time-out Control Register

ADR/SIZ
BIT 23
NAME
OPER
RESET
This register controls the DMAC time off timer, the DMAC time on
timer, and the VMEbus global time-out timer.
VGTO
TIME ON
TIME OFF
$FFF4004C (8 bits of 32)
22 21
TIME OFF
R/W
0 PS
These bits define the VMEbus global time-out value.
When DS0 or DS1 is asserted on the VMEbus, the
timer begins timing. If the timer times out before the
data strobes are removed, a BERR signal is sent to
the VMEbus. The global time-out timer is disabled
when the VMEchip2 is not system controller.
8 µs
0
64 µs
1
256 µs
2
3 The timer is disabled
These bits define the maximum time the DMAC
spends on the VMEbus:
16 µs
0
32 µs
1
64 µs
2
128 µs
3
These bits define the minimum time the DMAC
spends off the VMEbus:
0 µs
0
16 µs
1
32 µs
2
64 µs
3
LCSR Programming Model
20 19 18
TIME ON
R/W
0 PS
256 µs
4
512 µs
5
1024 µs
6
7 When done (or no data)
128 µs
4
256 µs
5
512 µs
6
1024 µs
7
17 16
VGTO
R/W
0 PS
2-67
2