Occupies a fair bit of a solderless breadboard. 5.5" long (55 pins) by 0.9" wide (9 pins).
Pins include:
86 IO pins (D0 to D85)
Vin
3.3V out
Vcc (3 pins)
7 Gnds
Reset
Aref on an inside pin if you want to play with it
Parts include:
16 MHz crystal
5V regulator fed from Vin with reverse polarity protection diode, 1000mA rated
3.3V regulator, fed from VCC, 1000mA rated (limited by VCC source, Vin or USB)
DTR enable header for those that don't want the USB port resetting the board
Power select header - VCC from USB-5V, or from 5V regulator
FTDI header - Gnd, USB-5V, Rx, Tx, DTR. 1K resistors connect Rx, Tx, to D0, D1.
Solder jumper to cut the SCK trace to the L LED
Solder jumper to cut the VCC trace to the Power LED
Reset diode to clamp any reset spikes to Vcc.
