Specifications

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from the same manufacturer we are able to use the same development board to
program multiple devices.
Voltage and current requirements:
The source voltage driving our main control unit is assumed to be 24V AC. This
assumption has been made based on the fact that the main control unit will be
installed where there was previously a thermostat mounted or installed in a new
HVAC system as the main thermostat. Most normal thermostats in HVAC
systems are powered by a 24V AC wire that is installed when the building is
constructed. The microcontrollers we have been considering normally need
between 3.0V and 3.6V AC in order to operate. This will be generated by
components on the PCB which will be discussed in the PCB Design section of
this paper.
The microcontroller in the main control unit is the component of the system that
will do the majority of the processing, make crucial decisions, and send and
receive all information. This will be the main “brain” of the system and is required
to perform perfectly in order for the system to operate to the standards we have
set. We have chosen to use the dsPIC33FJ256GP710A High Performance, 16-
Bit Digital Signal Controller manufactured by Microchip. We believe this part has
the necessary specifications to complete the tasks required by our design.
2.2.1 General Description
The main microcontroller (dsPIC33FJ256GP710A) has Operation Range, CPU,
I/O, Communication, Analog-to-Digital Converter, and other general
characteristics as follows:
The operation range of this microcontroller is close to the industry standard. A
supply voltage is needed to run the microcontroller and is limited to the range of
3.0 – 3.6V. The typical value for operation voltage is 3.3V DC. When powered
by a voltage between these parameters and kept between the temperatures of -
40˚C and 85˚C, the microcontroller is capable of up to 40 MIPS (Millions of
Instructions Per Second).
Operation Range:
o Supply Voltage of 3 – 3.6V
o Up to 40 MIPS
The microcontroller is optimized to be programmed in the C language which is
the programming language preferred by the group. The C language is the
language which we have the most background experience in. It contains a 16-bit
wide data path which will be sufficient for the data we are required to process,
two 40-bit accumulators to store our values of temperature and relative humidity
(values should never exceed 14 bits), 32/16 and 16/16 divide operations, and 16
x 16 fractional/integer multiply operations to convert the temperature and relative
humidity values from the form they are outputted by the sensor to an