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This device was built using AVRUSB firmware developed by extern Objective Development.
Meanwhile, a very similar Release 1.6 exists.
This Low-Speed device violates following USB specification rules:
* Detachable cable (must be captive for Low-Speed)
* Output drivers with 5 V (must be 3.3 V, but USB is 5 V tolerant)
* No differential data input (only one line D- is sampled)
* No data clock regenration while receiving (only at packet start)
* No error detection of input data (OUT direction), no time for CRC16
* Data transfer using BULK pipes (not specified for low-speed, but works on Windows – for Linux there is an “Alternate Setting” with INTERRUPT pipes instead)
* Output drivers with 5 V (must be 3.3 V, but USB is 5 V tolerant)
* No differential data input (only one line D- is sampled)
* No data clock regenration while receiving (only at packet start)
* No error detection of input data (OUT direction), no time for CRC16
* Data transfer using BULK pipes (not specified for low-speed, but works on Windows – for Linux there is an “Alternate Setting” with INTERRUPT pipes instead)
However, new to this firmware, following rules are accepted:
* Suspend detection and lowered suspend current (below 500 µA)
Click here for Source Code
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