Specifications

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main microcontroller to communicate with the other components of the main
control unit. In addition to these components, the main microcontroller is
required to connect to relays to control the other components of the HVAC
system such as compressors, air handlers, and a dehumidifier. Our sponsors
have specified that they would like 20 I/O ports available specifically for
controlling relays associated with components of the HVAC system. That
specification brings our total needed pin count to 33 I/O ports.
We have been shopping microcontrollers that have between 50 and 100 I/O
ports. This range of ports satisfies the requirements set by the sponsors, as well
as allows for more features to be added into the system in the future such as
control of air purification devices and scent emitting devices. If these features
are added, more interfacing with the main microcontroller will be required, along
with more software design and implementation.
Memory Type:
We are going to consider microcontrollers with Flash memory for our main
microcontroller. Flash memory is a type of EEPROM (electrically-erasable
programmable read-only memory) that is a non-volatile storage technology that
can easily be electronically erased and reprogrammed. Using flash memory in
the microcontroller will allow for changes to be made to the system by the
sponsors after the initial prototype is completed. From the research we have
done on microcontrollers that meet the specifications of our main microcontroller,
Flash memory seems to be the industry standard. The sponsors have made it
clear that they wish to add features to the system in the future and therefore we
feel that electronically erasable and reprogrammable memory is necessary, and
therefore Flash memory seems to be an excellent choice.
Development tools:
The development tool that is recommended by the manufacturer is the Explorer
16 Development board. It is manufactured by Microchip, which is the same
company that manufactures the microcontroller. For our project we will be
purchasing the Explorer 16 Starter Kit. The Starter Kit includes an MPLAB ICD2
In-Circuit Debugger, the Explorer 16 Development Board, a 9V universal power
supply, a serial cable, the MPLAB Integrated Development Environment (IDE),
and the Student Edition of the MPLAB C30 C Compiler for Microchip‟s 16-bit
devices, with tutorials and user manuals on CDROM. The Explorer 16
Development Board comes with an Alpha-numeric 16x2 LCD display, Microchip‟s
TC1047A analog output temperature sensor, and the PICTail Plus connector for
use with future expansion boards. The Explorer 16 Development Board is
designed to easily to a computer via USB or RS232 interface. Full
documentation including User Guides, Schematics, and PCB layout is included
on a CDROM.