Astro Spectra Plus Radio Power-Up/Power-Down Sequence - Motorola ASTRO Digital Spectra Plus Service Manual

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3.4.10 ASTRO Spectra Plus Radio Power-Up/Power-Down Sequence

The radio power-up sequence begins when the user actuates the control head's on/off switch. The
control head then produces the switched B+ (SWB+) output voltage which is routed to the command
board. Upon sensing the SWB+ voltage, the command board circuitry powers on the 9.6V and the
SW +5-V regulated supplies. The ASTRO Spectra Plus VOCON board contains two voltage
regulators, a 3-V regulator (U411) and a 1.8-V regulator (U410). The SW+5-V from the command
board is routed to the ASTRO Spectra Plus VOCON board via connector P501, and drives the two
regulators. When SW+5-V increases above 4.2 V and after a delay time chosen by C438, the voltage
detector (U412) disables the power-on reset to the Patriot IC (U300), enabling the device.
When the MCU comes out of reset, it fetches the reset vector in ROM at $FFFE, $FFFF and begins
to execute the code this vector points to. Among other things it enables the correct memory map for
the MCU. It configures all the transceiver devices on the SPI bus. The MCU then pulls the ADDAG
and KRSIC out of reset. It then configures the ADDAG through the SPI bus configuring among other
things, the DSP memory map. While this is happening, the DSP is fetching code from the FLASH
(U301) into internal RAM and beginning to execute it. It then waits for a message from the MCU that
the ADDAG has been configured, before going on.
During this process, the MCU does power diagnostics. These diagnostics include verifying the MCU
system RAM and verifying the data stored in the FLASH ROM. The MCU queries the DSP for proper
status and the results of DSP self tests. The DSP self tests include testing the system RAM and
verifying the program code. Any failures cause the appropriate error codes to be sent to the display.
If everything is OK, the appropriate radio state is configured and the unit waits for user input.
On power-down, the user actuates the radio's on/off switch, removing the SW_B+ signal from the
ASTRO Spectra Plus VOCON board. The host processor, after polling ROW3 (G2) and
acknowledging the signal loss, begins the power-down sequence. Since the host holds the 9.6-V/
5V_EN (enable) line active by controlling the state of the ROW5 / 5_EN line at P501, pin 15, this
does not immediately remove power. The host then saves pertinent radio status data to the external
FLASH (U301). Once this is done, the ROW5 / 5V_EN line is released (brought to logical 1), turning
off 9.6-V and the SW+5-V regulators on the command board. When the SW_+5-V slumps to about
4.2 Vdc, the voltage detector (U412) on the ASTRO Spectra Plus VOCON board activates the
system reset to the Patriot IC (U300). This turns off the host processor.
October 28, 2002
Theory of Operation: ASTRO Spectra Plus VOCON Board
6881076C25-D