Figure 3-33. Control Top Block Diagram (Apx 2000/ Apx 4000 (Two Knobs)) - Motorola APX 1000 Detailed Service Manual

Hide thumbs Also See for APX 1000:

Table of Contents

Theory of Operation

: Controller

3.2.6.1.2 APX 2000/ APX 4000 (Two Knobs)

The Top Control contains an On/Off & Volume Knob, a sixteen-position Channel/Frequency Switch,

and an emergency button. The Top Control also includes a TX/RX LED that is solid amber upon

receive, red on PTT, and blinks amber on secure RX and a status LED. The Top Control components

are mounted on flex.

When the On/Off & Volume Knob(S3) is switched to the 'ON' position, the switch is grounded and

MECH_SW is pulled low. MECH_SW is an input to MAKO (U6501). The logic low input enables an

external FET (Q6501) gate voltage, FET_ENX, which switches UN_SW_B+ to SW_B+ and turns the

radio on. Volume is also controlled through S3 and is an input to MAKO. The VOL signal is

connected to a potentiometer biased between ground and 2.775 V (R246) from MAKO. When the

volume knob is turned, the VOL signal level is converted to a code word by MAKO's ADC and read

by OMAP through SPI.

The orange programmable Top Button (S1) is typically used for emergency. It is also biased to

1.875 V (R6507) and is an input (EMERG_BTN_X) to the CPLD. A button press is detected when

EMERG_BTN_X is pulled low.

Figure 3-33. Control Top Block Diagram (APX 2000/ APX 4000 (Two Knobs))

Show Quick Links

Table of Contents

Apx 2000 Apx 4000li Apx 4000