JKD Freeduino 5V / 3.3V Hybrid (Duemilanove & Uno Arduino Compatible)

• Compatible with most shields designed for the Arduino Duemilanove and Arduino Uno
  • Shields designed to use the ISP header will need to be modified because the ISP header is in a different location.
• ATmega328 (datasheet) w/ Bootloader
• Additional header aligned to 0.1" grid for breadboard compatibility allows you to create your own shields without modifying or bending pins
• 14 digital input/output pins (of which 6 can be used as PWM outputs)
• 6 analog inputs (all can be used as digital pins)
• 8 level shifted I/O's via TXB0108 (enable or disable via jumper)
  • Digital pin 0 (PD0, RXD)
  • Digital pin 1 (PD1, TXD)
  • Analog pin 4 (PC4, SDA)
  • Analog pin 5 (PC5, SCL)
  • Digital pin 10 (PB2, SS)
  • Digital pin 11 (PB3, MOSI)
  • Digital pin 12 (PB4, MISO)
  • Digital pin 13 (PB5, SCK)
• Level shifted I/O's can be supplied with integrated 3.3V supply or by an external power source less than 5V
• 16 MHz crystal oscillator
• Mini USB connection (Kit version includes standard sized USB connector)
  • Can be used to power the board at full power... no 500mA limit when using a USB power adapter.
• Power header
  • 3 pin 0.1" header with center VIN
  • 2 pin JST connector
• On board 3.3 volt and 5.0 volt regulators can supply up to 1 amp of power from an unregulated input over 6 volts
• ISP header
• Reset button
• Power indicator LED
• RX/TX LED
• Integrated USB->Serial adapter for programming from the Arduino IDE or other STK500 compatible software
• Reset jumper for disabling auto-reset and configuring DTR or RTS as reset signal

JP1
JP1 is the auto-reset configuration jumper.  In most cases you would want to leave the jumper set on DTR and RESET.  You can move the jumper to RTS and RESET if you would like to use RTS as your auto-reset line.  You can remove the jumper completely to disable the auto-reset functionality.

JP2
JP2 allows you to enable or disable the Level Shifter (TXS0108E). 

Version 3 - When the jumber is set on OE and GND the level shifter will be disabled and all pins will be set to a high-inpedance state.  When the jumper is set on OE and VCCA the level shifter will be enabled.
Version 2 - The following only applies to V2 and adjusts for the fact that VCCA and OE are labeld incorrectly.  They are reversed.  When the jumber is set on OE and VCCA the level shifter will be disabled and all pins will be set to a high-inpedance state.  When the jumper is set on OE and GND the level shifter will be enabled.

JP3
JP3 should always have a jumper installed for 3.3 volt operation.  This jumper connects the 3.3 volt supply to VCCA of the level shifter which sets the level-shifter I/O's to 3.3V.  If you need to operate the level shifter I/O's at a voltage other than 3.3V, you can remove the jumper and supply the VCCA pin on JP3 on on J6 with the desired voltage.  Note that the voltage on VCCA should be between 1.2 V and 3.6 V and should never exceed 4.6 V

J6
J6 is supplied with a male 2x5 pin 90° connector.  This connector does not come pre-installed on any version of the board.  This allows for greater flexibility in the way you can connect to it.  All pins on this connector are level transtaled to the voltage applied to VCCA.  Note that in the standard configuration of JP3 (jumper installed) VCCA is supplied with 3.3V from the on-board regulator.  In this configuration the VCCA pin can be used to supply 3.3V to any connected device.  If JP3 is removed, VCCA must be supplied with a reference voltage. 

Power
The main power connector can be configured in 2 ways.  You can either install the supplied JST connector or the 3 pin header.  When using the 3 pin header, note that the center pin is + and the 2 outside pins are -.  The power input can be supplied with up to 20V but it is recommended that you do not exceed 9 volts and supply with a minimum of 6.2 volts.  The VIN pin on the shield header can also be used to supply unregulated power to the board.  If supplying power via the USB connector, it must not exceed 5V.    The power LED will stay lit as long as the board is receiving sufficient power.

L D13
This LED is connected to digital pin 13 of the Arduino interface.  This LED will flash when the when the standard Blink Sketch example is loaded onto the board.  It will also flash when digital pin 13 is accessed with other sketches.  Note that in some cases this may interfere with your project.  You may choose to not install this or remove it if it is not necessary.

BOM For Standard Kit (must be installed/soldered by user)

• C1, C2 - 22pF (only provided if a crystal is used instead of a ceramic resonator)
• 16MHz crystal or ceramic resonator
• C7, C8, C9, C10 - 10uF
• C3, C4, C5, C6 - 0.1uF
• R4, R5, R6, R(D13) - 1K ohm
• R1 - 10K ohm
• PWR, L D13 - Red & Yellow LED
• 3 pin 90 degree header (power)
• JST Connector (alternate power)
• USB Connector
• JP3, JP2, JP1 include male headers and shunts
• Atmega328P-PU
• 28 pin DIP Socket
• J6 90 degree 2x5 female header
• Two 1x6 female headers
• Two 1x8 female headers
• 2x3 ICSP male header
• Reset switch

Board Layout
Schematic