User manual

ECE 477 Final Report Spring 2004
All three of these designs have a dual USART capability which is a must for our project
design. These three devices differ in only memory sizes, boot loader support, and interrupt
vector sizes. Also, power consumption for each of these three designs is similar. For our design,
we need to have a considerable amount of memory for the graphical LCD menu display for
storage of graphics and character generation. We chose the ATmega88 over the ATmega44
because it has twice as much EEPROM and SRAM memory where the ATmega168 contains the
same amount of EEPROM and SRAM as the ATmega88.
LCD Monitor:
There was much debate about which LCD display to use for the design. We disagreed on
using either a 20x4 character display or a small graphics display. We decided that a graphic LCD
display would be preferable if we could sample a part for free, but if not, we would just buy a
character display since the graphical models cost around $60 or more. While we were rejected
by Hantronix for parts sampling, Microtips agreed to send us the 128x128 Graphics Display [3-
5]. This cuts down on our budget considerably since the LCD monitor would have been the most
expensive part in our entire design.
Transceiver:
We discussed both a Bluetooth/802.11 and a Serial RF solution. It was tentatively
decided that Serial RF was easier to integrate and cheaper to implement. Our design does not
need to have a high data rate since the menus will be uploaded around once a day or less. Also
the data sent from the handheld device to the base station will be encoded such that the amount
of data sent is small as possible. The Serial RF solution allows us to eliminate the software
overhead that would be required with the Bluetooth/802.11 implementation.
Initially we didn’t find many low cost solutions out there for single chip transceivers.
Two that we did happen to find were the AT86RF211 [3-3] from Atmel and the nRF401 [3-4]
Transceiver from Nordic VLSI.
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