/* UsiSerial by me@frank-zhao.com
 *  
 * UsiSerial is a simple wrapper around the code from AVR307 so that Arduino can use USI to implement a hardware serial port
 *
 * The USI class works almost exactly like HardwareSerial
 * So you can use print and println and other functions like that
 *
 * PORTB0 is DI, thus it is RX
 * PORTB1 is DO, thus it is TX
 * default baud rate is 19200, which can only be changed in USI_UART_config.h
 * only some baud rates will work, depending on CPU frequency
 * buffers are small to save memory, since this library is designed for ATtiny
 * testing was done using a 16 MHz Trinket
 *
 * Important note: requires Timer1 and PCINT to be occupied
 *  
  Copyright (c) 2013 Frank Zhao
  All rights reserved.

  UsiSerial is free software: you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as
  published by the Free Software Foundation, either version 3 of
  the License, or (at your option) any later version.

  UsiSerial is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with UsiSerial. If not, see
  <http://www.gnu.org/licenses/>.
*/