Control and Design of Microgrid Components - Power Systems ...

The DSP is an integrated chip mounted on a board that handles several peripherals for
interfacing with the external world. Figure 6.7 shows the block schematic highlighting these
peripherals:
i) Analog to Digital Conversion (ADC) to import measurement from the outside world as a
string of bits stored in a mapped data memory
ii) Crystal oscillator clock that generates the square wave pulses to operate the CPU inside the
integrated circuit
iii) Parallel pins to allow the gate signals to be passed to the signal amplifying board
iv) Digital to Analog Conversion (DAC) that is very useful when debugging the control routine
allowing output signals to be displayed on the oscilloscope
v) Parallel connection to connect to the computer card that sends the compiled code to be
stored in the program memory of the integrated circuit
vi) Interrupt request controller to be able to set up priorities in hardware and software queues
of tasks that are waiting to be processed by the DSP
vii) Timer controller that can be used to generate any triangle or square wave that may be
needed
viii) Serial port to allow to exchange values from and to the board with the computer
DSP Board
External
Measurements
ADC
IRQ
DAC
Oscilloscope
Probe
Oscillator
Clocks
Integrated
Circuit
Parallel Pins
Inverter
Gates
Executable
from Computer
Debugging Utility
to Computer
Parallel Port
Serial Port
Timer
Module
Figure 6.7 DSP Peripherals.
The DSP is a Motorola DSP56F805EVM board. Internally, this board handles every signal as a
16 bit word, and uses the fractional integer Arithmetic Logic Unit (ALU), a mathematical
processor that supports only two kind of operations between register values: sum and
multiplication. The ALU can only represent and use numbers between -1 and 1, demanding extra
care when coding the control blocks. Every variable will have to be rescaled so that its value will
never exceed the absolute value of unity, not even during overshooting transients. This board
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