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fixed typo for README.md

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+
+
+ CDC-232
+
+
+ This is the Readme file to firmware-only CDC driver for Atmel AVR
+ microcontrollers. For more information please visit
+ http://www.recursion.jp/avrcdc/
+
+
+SUMMARY
+=======
+ The CDC-232 performs the CDC (Communication Device Class) connection over
+ low-speed USB. It provides the RS-232C interface through virtual COM
+ port. The AVR-CDC is originally developed by Osamu Tamura.
+ Akira Kitazawa has significantly contributed to improve this software.
+
+
+SPECIFICATION
+=============
+ AVR-CDC with USART (ATmega8/48/88/168)
+ speed: 600 - 38400bps
+ datasize: 5-8
+ parity: none/even/odd
+ stopbit: 1/2
+ controls: DTR, RTS, CTS
+
+ AVR-CDC with USART (ATtiny2313)
+ speed: 600 - 38400bps
+ datasize: 8
+ parity: none
+ stopbit: 1
+
+ AVR-CDC without USART (ATtiny45/85)
+ speed: 1200 - 4800bps
+ datasize: 8
+ parity: none
+ stopbit: 1
+ supply current: 8-15mA
+
+ The RTS indicates that the receive buffer is not full, and the CTS stops
+ sending data at '0' input. These controls cannot be controlled/read by the
+ host PC (ATmega).
+
+ Internal RC Oscillator is calibrated at startup time on ATtiny45/85.
+ When the other low speed device is connected under the same host
+ controller, the ATtiny45/85 may fail to be recognized by the downstream
+ broadcast packet.
+
+ Although the CDC protocol is supported by Windows 2000/XP/(Vista/7), Mac
+ OS 9.1/X, and Linux 2.4 or 2.6.31-, low-speed bulk transfer is not allowed
+ by the USB standard. Use CDC-232 at your own risk.
+
+
+USAGE
+=====
+ [Windows XP/2000/Vista/7]
+ Download "avrcdc_inf.zip" and read the instruction carefully.
+
+ [Mac OS X]
+ You'll see the device /dev/cu.usbmodem***.
+
+ [Linux]
+ The device will be /dev/ttyACM*.
+ Linux <2.6.31 does not accept low-speed CDC without patching the kernel.
+ Replace the kernel to 2.6.31 or higher.
+
+
+DEVELOPMENT
+===========
+ Build your circuit and write firmware (cdcmega*.hex/cdctiny*.hex) into it.
+ C1:104 means 0.1uF, R3:1K5 means 1.5K ohms.
+
+ This firmware has been developed on AVR Studio 4.18 and WinAVR 20100110.
+ If you couldn't invoke the project from cdc*.aps, create new GCC project
+ named "at***" under "cdc232.****-**-**/" without creating initial file.
+ Select each "default/Makefile" at "Configuration Options" menu.
+
+ There are several options you can configure in
+ "Project/Configuration Options" menu, or in Makefile
+
+ (General)
+ Device Select MCU type.
+ Frequency Select clock. 16.5MHz is the internal RC oscillator.
+ (ATtiny45/85)
+ 3.3V Vcc may not be enough for the higher clock operation.
+
+ (Custom Options) add -D*** to select options below.
+ UART_INVERT Reverse the polarity of TXD and RXD to connect to RS-232C
+ directly (ATtiny45/85).
+ Enables software-inverters (PC0 -|>o- PB0, PC1 -|>o- PB1).
+ Connect RXD to PB0 and TXD to PC1. The baudrate should be
+ <=2400bps (ATmega48/88/168).
+
+ Rebuild all the codes after modifying Makefile.
+
+ Fuse bits
+ ext H-L
+ ATtiny2313 FF CD-FF
+ ATtiny45/85 FF CE-F1
+ ATtiny45/85(Xtal) FF 6E-FF / FF 6E-F1 (PLL)
+ ATmega8 8F-FF
+ ATmega48/88/168 FF CE-FF
+
+ SPIEN=0, WDTON=0, CKOPT(mega8)=0,
+ Crystal: Ex.8MHz/PLL(45,461), BOD: 1.8-2.7V
+
+ * Detach the ISP programmer before restarting the device.
+
+ The code size of AVR-CDC is 2-3KB, and 128B RAM is required at least.
+
+
+USING AVR-CDC FOR FREE
+======================
+ The AVR-CDC is published under an Open Source compliant license.
+ See the file "License.txt" for details.
+
+ You may use this driver in a form as it is. However, if you want to
+ distribute a system with your vendor name, modify these files and recompile
+ them;
+ 1. Vendor String in usbconfig.h
+ 2. COMPANY and MFGNAME strings in avrcdc.inf/lowbulk.inf
+
+
+
+ Osamu Tamura @ Recursion Co., Ltd.
+ http://www.recursion.jp/avrcdc/
+ 26 June 2006
+ 7 April 2007
+ 7 July 2007
+ 27 January 2008
+ 25 August 2008
+ 10 April 2009
+ 18 July 2009
+ 28 February 2010
+

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