LCSR Programming Model

Local Bus to VMEbus Requester Control Register

ADR/SIZ

 

 

$FFF40030 (8 bits [7 used] OF 32)

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

15

14

13

12

11

10

9

 

8

 

 

 

 

 

 

 

 

 

NAME

ROBN

DHB

DWB

 

LVFAIR

LVRW

LVREQL

 

 

 

 

 

 

D

 

 

 

 

 

 

 

 

 

 

 

 

OPER

R/W

R

R/W

 

R/W

R/W

 

R/W

 

 

 

 

 

 

 

 

 

RESET

0 PS

0 PS

0 PSL

 

0 PS

0 PS

 

0 PS

 

 

 

 

 

 

 

 

 

 

This register controls the VMEbus request level, the request mode, and release mode for the local bus to VMEbus interface.

LVREQL

These bits define the VMEbus request level. The request

 

is only changed when the VMEchip2 is bus master. The

 

VMEchip2 always requests at the old level until it

 

becomes bus master and the new level takes effect. If the

 

VMEchip2 is bus master when the level is changed, the

 

new level does not take effect until the bus has been

 

released and re-requested at the old level. The requester

 

always requests the VMEbus at level 3 the first time

 

following a SYSRESET.

 

0

The request level is 0.

 

1

The request level is 1.

 

2

The request level is 2.

 

3

The request level is 3.

LVRWD

When this bit is high, the requester operates in the

 

release-when-done mode. When this bit is low, the

 

requester operates in the release-on-request mode.

LVFAIR

When this bit is high, the requester operates in the fair

 

mode. When this bit is low, the requester does not operate

 

in the fair mode. In the fair mode, the requester waits until

 

the request signal line for the selected level is inactive

 

before requesting the VMEbus.

DWB

When this bit is high, the VMEchip2 requests the

 

VMEbus and does not release it. When this bit is low, the

 

VMEchip2 releases the VMEbus according to the release

mode programmed in the LVRWD bit. When the VMEbus has been acquired, the DHB bit is set.

2

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Motorola MVME172 manual Local Bus to VMEbus Requester Control Register, Lvreql, Lvrwd, Lvfair, Dwb