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===== DigiCDC - Digispark USB CDC Serial Library =====

The DigiCDC library allows the Digispark or Digispark Pro to appear to a computer as a Virtual Serial Port when connected by USB. This makes it appear just like a standard Arduino and allows the use of the Serial Monitor built into the Arduino IDE.

DigiCDC was based on the V-USB project and avrcdc project - the first version (the hard work) was created by ihsan Kehribar (http://kehribar.me) and then turned into an Arduino library and refined by Erik Kettenburg (Digistump)

=== Limitations and Usage ===

The DigiCDC library is based on V-USB - because the Digispark does not have hardware USB support. This presents some unique limitations in how it works - outlined below:

  - You must explicitly include the DigiCDC library - by placing the following at the top of your sketch <code>#include <DigiCDC.h></code>
  - It uses a lot of RAM - half of the Digispark's RAM - so only include it when needed and watch your RAM usage. You can wrap strings in F() (ie. SerialUSB.print(F("test")) ) to put the string in flash memory instead of RAM
  - You use it the same as Serial on an Arduino but with SerialUSB instead (ie. SerialUSB.read() instead of Serial.read() ) - The Pro also has Serial defined - but that refers to the hardware Serial port on Pins 6 and 7.
  - The begin statement does not need a baudrate - it is a CDC device so it does not have a set baud rate - just use SerialUSB.begin()
  - You must install the driver for windows - it is part of the driver package found in the Digispark Arduino release. 
  - It is slow - it transfers data very slowly - because it is a low speed USB device doing the job of a Standard speed device - and doing it all virtually without actual hardware support!
  - Like all of our V-USB libraries you must use its delay function instead of delay() - so use SerialUSB.delay() when you need a delay in your code.
  - SerialUSB.delay() or SerialUSB.refresh() must be called every 10ms or less in your code if no other SerialUSB call is made in that code.
  - Advanced experimentation: You can use SerialUSB.setDelay() to adjust the delay between each character written to the host (in ms) - 45 is the default, some people have luck with as little as 9ms.

=== Examples ===

Examples can be found in the Digistump Arduino release (1.5.8C or higher) under File->Examples->DigisparkCDC

=== Android Devices ===

DigiCDC can be used to make the Digispark appear as a Serial device to an Android device when attached to an Android device's OTG port. The device must support Serial/CDC devices via OTG

Android App Examples (using phonegap/cordova and editable with only working knowledge of javascript and HTML):

https://github.com/digistump/Digispark_Cordova_CDCLED

https://github.com/digistump/Digispark_Cordova_CDCEcho

Phonegap/Cordova Plugin used in the examples above to connect to a DigiCDC device:

https://github.com/digistump/DigiCDCPhonegap

(plugin use FTDriver by Keisuke SUZUKI  https://github.com/ksksue/FTDriver)
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