Pioneer 2 User Manual

Page 59

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Pioneer Mobile Robots

53

Onboard Computer Option

With the "computer-ready" option (Figure B-2) available with the DX and AT models, the Pioneer 2
Motor-Power Board is specially populated with connectors and circuits to provide separate DC-DC condi-
tioned, 7A @ 5 VDC power to an onboard computer and its accessories, and enhanced (3A instead of the
standard 1.5A) DC-DC conditioned 5VDC power to the other onboard systems and accessories, including
radio Ethernet. And, in conjunction with software, the circuit provides for automatic, unattended, crash-less
shutdown of the onboard computer, either when manually power-down or when the battery voltage drops
below 10 VDC.

Power Switch (J7) and Delayed Shutdown Logic

A simple SPDT switch controls logical power to the computer-power section of the Motor-Power Board.
When on, the switch provides Vpp to the input of a voltage comparator which output controls the
computer's DC-DC voltage converter. Designed to provide for "crashless" shutdown of the computer in the
event of a power brownout or for unattended shutdowns, if Vpp drops below 10 VDC, the comparator
automatically initiates a two-minute delay (LMC555 timer-mediated) before computer power (not system-
wide) shutdown.

Similarly, when the computer power is manually switched off, the comparator is grounded (below 10 VDC,
of course) and the same two minute-delayed shutdown occurs.

In all cases, power shutdown, but not necessarily computer software shutdown, is canceled if power is
restored to above 10 VDC, either by connecting the Battery Charger or by hot-swap refreshing the
batteries.

Also, you may disable the two-minute delay circuitry (switched or low-voltage shutdown immediate) by
moving the jumpers on both J3 and J6 on the Motor-Power Board to the pins opposite their ON position.

Table B-2. Computer Option Power Switch (J7)

Pin #

Connection

1

Vcc

2

Gnd

3

Vpp

Power-State Logic

A 9-pin DSUB receptacle (P1) on the Pioneer 2 Motor-Power Board provides a logic-level shutdown
indicator (DCD line pin 1) which state goes low when computer power shutdown is first initiated. The
onboard computer may use this line state to initiate software-mediated shutdown, such as provided by
genpowerd for RedHat Linux PCs.

Table B-3. Power State 9-pin DSUB receptacle (P1)

1

2

3

4

5

6

7

8

9

DCD

20K
pull-up
pins 4,6

nc

nc

pin 6

nc

pin 4

nc

nc

Gnd

Computer Power

A common 4-conductor, bevel-keyed connector (J5) provides 5 VDC @ 7A power for the onboard

computer, and battery power for the optional 12VDC fan.

Table B-4. Computer power and fan connector (J5)

Pin #

Connection

1

Vpp

2

Gnd

3

Gnd

4

5VDC @ 7A

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