Motorola pro7100 Service Manual download pdf (Page 18)

2-4 Theory of Operation

2.2.3 Emergency

The emergency switch (J0501, pin 9), when engaged, grounds the base of Q0662 via the

EMERGENCY CONTROL line. This switches Q0662 off and resistor R0662 pulls the collector of

Q0662 and the base of Q0663 to levels above two volts. Transistor Q0663 then switches on and pulls

the collector of the npn transistor within Q0661 to ground level This enables the voltage regulators

via Q0641. When the emergency switch is released, R0541 pulls the base of Q0662 up to 0.6 volts

causing the collector of transistor Q0662 to go low (0.2 volts), switching Q0663 off.

While the radio is on, the µP monitors the voltage at the emergency input on the accessory

connector via pin 60 and the GP5 IN ACC9 line. Three different conditions can exit: no emergency,

emergency, and open connection to the emergency switch. If no emergency switch is connected or

the connection to the emergency switch is broken, the resistive divider R0541/R0512 sets the

voltage to about 4.7 volts. If an emergency switch is connected, a resistor to ground within the

emergency switch reduces the voltage on line GP5 IN ACC9 to inform the µP that the emergency

switch is operational. An engaged emergency switch pulls line GP5 IN ACC9 to ground level. Diode

D0179 limits the voltage to protect the µP input.

While the EMERGENCY CONTROL signal is low and INT SW B+ is on, the µP starts execution,

reads that the emergency input is active through the voltage level of line GP5 IN ACC9, and sets the

DC POWER ON output of the ASFIC CMP, pin 13 to a logic high. This keeps Q0661 and Q0641

switched to allow a momentary press of the emergency switch to power up the radio. When the µP

has finished processing the emergency press, it sets the DC POWER ON line to a logic 0. This turns

off Q0661 and the radio turns off. Notice that the µP is alerted to the emergency condition via line

GP5 IN ACC9. If the radio is already on when the emergency is triggered, the DC POWER ON signal

is already high.

2.2.4 Mechanical On/Off

This refers to the on/off/volume knob located on the control head which is used to turn the radio on

and off and control the volume.

If the radio is turned off and the on/off/volume knob is pressed, line ON OFF CONTROL (J0401, pin

11) goes high and switches the radio’s voltage regulators on as long as the button is pressed. The µP

is alerted through line ON OFF SENSE (U0101, pin 6) which is pulled to low by Q0110 while the on/

off/volume knob is pressed. In addition, an interrupt is generated at µP, pin 96. The µP asserts line

DC POWER ON via ASFIC CMP, pin 13 high which keeps the radio switched on. The µP switches

the radio off by setting DC POWER ON to low via ASFIC CMP pin 13.

2.2.5 Ignition

Ignition sense prevents the radio from draining the vehicle’s battery because the engine is not

running.

When the IGNITION input (J0501, pin 10) goes above 5 volts, Q0661 is turned on via line IGNITION

CONTROL. Q0661 turns on INT SW B+ and the voltage regulators by turning on Q0641 and the µP

starts execution. The µP is alerted through line GP6 IN ACC10. While the on/off button is pressed, a

high signal turns Q0181 on, which pulls µP, pin 74 to low. If the software detects a low state it asserts

DC POWER ON via ASFIC, pin 13 high which keeps Q0661 and Q0641 and the radio switched on.

When the IGNITION input goes below 3 volts, Q0181 switches off and R0181 pulls µP, pin 74 to high.

This alerts the software to switch off the radio by setting DC POWER ON to low. The next time the

IGNITION input goes above 5 volts the above process is repeated.

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 108 109

Comments to this Manuals

No comments

Motorola pro7100 Service Manual Page 18

Comments to this Manuals

Related products and manuals for Car media receivers Motorola pro7100