Specifications

PC/II+p Board Technical Reference Manual 64

7.22 Reset Switch

PC/II+p responds to a "reset switch" signal input (MR-RSTSW#) from the Mass I/O Connector, J904. The

reset switch signal is Active Low. It should be left unconnected if unused. See the column, "SIGNAL

DESCRIPTION", in Table 32

below, for requirements.

The on-board supervisor asserts System RESET for as long as MR-RSTSW# is held low, and for 130 to 200

ms after this signal is floated. An on-board pull-up of 40 KΩ is used.

The pinout for this interface is given in Table 32

7.22.1 Reset Switch Interface Pinout

Table 32 Signals – J904 – Reset Switch Interface

PIN NAME PIN# SIGNAL NAME SIGNAL DESCRIPTION

MR-RSTSW#

e8 Manual Reset Hard Reset Input, Active low. This signal drives the

Manual-Reset Input. An internal 40k• pull-up resistor

(typical) is provided on this signal line. Leave open if

unused. Reset remains asserted as long as this signal

is held low and for 200ms (typical; minimum 140ms)

after this signal is floated.

Normally there are two levels expected on this input

line, an Active LOW level (-0.03V to +0.5V), and an

Inactive HIGH level (Vcc-0.5V to Vcc+0.3V).

However, for compatibility with the Megatel 104Family,

Megatel strongly recommends that this input line

should be tied to GROUND to activate the RESET

function, and left OPEN otherwise. In any case, under

no circumstances should this line be pulled higher than

VCC3+0.3V (for the PC/II+p, this limit is +3.6V).