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Design Considerations

Noah Erickson edited this page Apr 11, 2015 · 10 revisions

Microcontroller

Unit Cost Fab Board Can Controller Can Library SPI, I2C, UART etc
ATMega328 $5 Yes No No Yes
AT90CAN $8 Yes Yes Yes Yes
ATSAM3X $12 Yes Yes Kinda Yes
Arduino Uno $30 No No No Yes
Arduino Due $50 No Yes Kinda Yes

The AT90CAN was the first option considered. The team had previous experience with Atmel AVR microcontrollers and the AT90CAN had a built in CAN transceiver. The microcontroller was proposed for use in a design review and after a brief discussion it was determined that a better microcontroller could be found. After a bit of further research the ATSAM3X was decided upon due to it being a 32-Bit Arm core running at 84 MHz versus the 8-bit AT90CAN running at 16 MHz. The more powerful ATSAM3X will miss less CAN messages than the AT90CAN and the only tradeoff is a few dollars and a little bit more design work.

A printed circuit board(PCB) will be created for the ATSAM3X with all the necessary components. This includes a voltage regulator, bypass caps as well as terminals to connect to the Viking Motorsports electric car CAN bus.

Screen Options

Unit Cost Size Color Visibility Software
Earth LCD $219 3.5” Yes Yes Yes
New Haven $60 4.9” No Yes No
Sun LCD ??? 3.5” Yes Yes No
4D Systems 4.3” $109 4.3” Yes No Yes
4D Systems 3.5” $89 3.5” Yes No Yes

The 4D Systems 3.5” screen has been chosen to be the display of the digital dash. This choice is primarily driven by cost, size and 4D Systems providing an IDE to create a simple GUI

CAN Transeiver

Unit Cost Max Transfer Rate Multiple CAN Networks
AMIS-42700 $6 1 Mbit/Sec Yes (2)
MCP-2551 $1.50 1 Mbit/Sec No

GUI Layout

The GUI must be kept simple. The driver will only briefly be able to glance at the digital dash so it must be colorful and simple.