Specifications

Table Of Contents
MAINTENANCE
Page 121 MRC-565 Packet Data Radio Operations & Maintenance
6.2.4 Coldfire Microprocessor Peripherals and Serial Configuration
The MCF54455 Coldfire (CF) DMA-Supported Serial Peripheral Interface (DSPI) and its I2C
serial interface supply serial communications to external peripherals. The CF DSPI select outputs
are routed to the CPLD. The CPLD provides digital logic to produce serial chip selects.
When the radio is booted, the CF loads the FPGA hardware program and DSP firmware
programs via the CF DSPI. Utility ADC U12 is read via the DSPI. The RX Synth Clock U85, the
QDUC U63, and the high speed ADC U71 are configured by DSPI. Radio parameter serial
storage memory nonvolatile EEPROM U62 is read and written via DSPI. I2C is used to
configure clock ICs U51 and U60.
The CF Several peripherals are available on the MRC-565 microprocessor: 10-bit A/D converter,
a temperature sensor and a real time clock. Four channels of the A/D converter are utilized in the
transmitter/receiver hardware. The temperature sensor is connected to one channel of the A/D
converter and can be accessed directly by the user. The remaining 6 A/D converter channels are
accessible to the user . The third peripheral, a real time clock, is available for keeping system
time and time stamping critical events.
6.2.5 Power Fail Detection/Protection
The MRC-565 microprocessor utilizes a high precision analog threshold detector to determine
when power fails are occurring. A high priority interrupt is activated on the MCF 54455
processor when a pending power fail is detected after which the processor is guaranteed
approximately 1 msec to prepare for power failure. If no power failure actually occurs, the
internal watchdog wakes the MCF54455 in 45 seconds for normal operation. During an actual
power fail, the microprocessor restarts once system power returns.
6.2.6 Voltage Regulators
The CMU contains several voltage regulators, as described below. In addition to these regulators
there is a 3.3V Primary regulator that runs directly from the +10-16V input. This regulator
provides power for the Real Time Clock (RTC) chip U60 and the power ON control chips. This
voltage is powered on whenever the 10-16VDC is applied to the MRC 565. Its current drain
when all other regulators are power off is less than 2 ma. If power is disconnected from the unit
the RTC will loses its TOD and Alarm Clock settings and must be re set by the operator.
6.2.6.1 Input Switching Regulator
A Switching regulator chip is used to provide a stable 5.3 volt supply to all of the CMU circuits.
The input to this regulator is obtained from the +10-16V input from the PA Interface Connector.
The regulator is capable of supplying a minimum of 500 ma of current to the CMU. The
regulator operates at an efficiency exceeding 85%.
The Regulator can be powered down by a PWR-ON control signal, generated by the CPLD..