Specifications

25
The I
2
C protocol will be used to interface the main microcontroller to the
temperature and relative humidity sensor. The microcontroller can support up to
two I
2
C modules at one time. This leaves one I
2
C port available should another
component be added in the future that requires an I
2
C connection.
I
2
C:
 2 modules supported
 Full Multi-Master Slave mode support
 7 and 10 bit addressing
The UART protocol will be set up to be our serial connection to the LCD display.
The microcontroller supports up to two modules using UART at any one time.
This leaves one UART port available should another component be added in the
future that requires a UART connection.
UART:
 2 modules supported
 Interrupt on address bit detect
 Interrupt on UART error
 Wake-up on start bit from sleep mode
The microcontroller has two ADC modules it can use to transfer input analog
voltages into a digital number proportional to the input voltage or current. This
will be important for issues where the device connected to the main
microcontroller is providing an analog voltage so that the main microcontroller
can convert that voltage into a high or low state and proceed as necessary with
decision making processing.
Analog-to-Digital Converters:
 2 ADC modules
 32 channel
The main microcontroller is where the majority of our processing will be done,
and where most of the code we write will be stored. The dsPIC33FJ256GP710A
has 256Kb on board Flash memory which will be enough space for all of our
instructions. It also has 30Kb RAM which should allow the processing to be done
reasonably fast.
During selection of the main microcontroller we considered several options. Most
of the options were similar in functionality. We decided on the
dsPIC33FJ256GP710A because it met our requirements for number of I/O pins,
number of interfacing ports, and was made by Microchip. As we were selecting
parts, we found that it was going to be possible to get the majority of our parts
from a single manufacturer. We considered this as an advantage as we believed
it would be likely that the manufacturer designed their parts to be implemented
with one another. We also considered cost of the microcontroller when selecting