Motorola VRS750, Service Manual

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On. SW7.5V is connected back to 7.5 V again. At this point the
microprocessor on the transceiver has been reset and is now in
bootstrap mode.
To prevent mobile bus messages from corrupting the flash
programming of the transceiver, the control signals to U102-3, U105-2
and U105-3 are applied with 9.6V to disconnect the Bus+ (P102-5),
Bus- (P102-14) and Busy (P102-23)lines from the mobile when the
BOOT-CNTRL line is grounded.
Program Sense
The PROG_SENSE signal(J30-10) is monitored by the VRS to detect
when the programming cable is connected at connector P101. This
line will be pulled to ground when the programming cable is
connected or will be 3.3VDC when the programming cable is not
connected.
The programming cable is used when adjusting the VRS using the
Tuning Tool (refer to “VRS750 Global Tuner,” Chapter 2) or when
updating the VRS firmware using the VRS750 Upgrade Kit (refer to
“VRS750 Upgrade Kit,” in Chapter 2).
To prevent mobile bus messages from corrupting the codeplug
programming and/or tuning of the transceiver, the control signal to
U105-1 pin 10 is driven to ground.
Mode Configuration
There are various operating modes of the VRS750. The mode is selected
at power-up based on the settings of dipswitch S1 pins 1, 2 and 3. Pin
4 is unused. Table 6 shows the supported modes:
Normal mode is the default and standard configuration for the
VRS750. The Test Mode configuration is used when the transceiver
requires tuning. The VRS750 can be put into Test Mode by placing S1
Pins 1, 2, and 3 to the OFF position before system power-up. When this
setting is detected by the VRS µP at power up, the following will occur:
• VRS TEST is displayed momentarily on the control head.
• Portable Priority Interrupt is disabled.
• VRS TOT disabled.
• TX PL disabled.
Table 6. VRS750 Supported Modes
Operating Mode S1 Pin 1 S1 Pin 2 S1 Pin 3
Normal On On On
Test Mode Off Off Off
ATE Test Mode On Off Off
Professional CPS Mode Off On On