ECESmartAccessoryRefDesign¶

NEW IDEA (10/25/2010)¶

• Use an arduino platform (common with prototypers) so we can write and program code from the Arduino IDE
• Eagle schematics are freely available, so we can download their files and rework the schematic to suit our liking
• Using this: http://www.sparkfun.com/commerce/product_info.php?products_id=9218
  • Cost of the chip (ATMega328P vs ATtiny261) increases, but added functionality outweighs to additional cost link
  • Alternate source, actually cheaper though supply may be intermittment http://www.sparkfun.com/commerce/product_info.php?products_id=9261

Pinouts¶

• (6) ADC
  • Pinout at least 4, depending on space
• (14) DIO
  • External Interrupt Pins
  • (6) PWM Pins (backed by hardware)
  • Programming Header (for FTDI breakout)
  • I2C (back to ScoutFly)
  • TX/RX
  • Status LEDs
• All headers will be 3x1
  • |GND|5V|SIG|
  • The 5V and GND lines will be on a bus. May need to provide isolation on the ADC pins?
  • 1A-1.5A re-settable fuse

Parts¶

Description	Qty	Vendor	Part No.	Link	$/ea
1A Resettable Fuse	1	Digikey	507-1482-1-ND	Page	$0.37
ATMEGA328P	1	Digikey	ATMEGA328-AU-ND	Page	$3.83
On/Off Slide Switch	1	Digikey	SW619-ND	Page	$0.62

Accessory Header¶

• Plugs into accessory header using 5x2 male CGRID pins, 90deg bend

(pin 1 is upper left)

5V	PIN0	PIN1	DET	SDA
GND	PIN2	PIN3	---	SCL

Notes¶

• Should have a power switch (sliding) and a user button
• Red LED on power line
• Eagle Libraries
  • http://www.cadsoft.de/cgi-bin/download.pl?page=/home/cadsoft/html_public/download.htm.en&dir=eagle/userfiles/libraries

---

Archived Ideas¶

Processor¶

• ATtiny261
  • Operate at +5V
  • 8bit, 10Mhz processor
  • (11) 10bit ADC
  • 15 GPIO
  • USI (TWI and I2C compatible, as master or slave)