Motorola MVME172 User Manual download pdf (Page 133)

LCSR Programming Model

http://www.mcg.mot.com/literature 2-55

Local Bus to VMEbus Requester Control Register

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.

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

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

1 ... 132 133 134 ... 354

No comments

Motorola MVME172 User Manual Page 133