This file documents changes in the firmware-only USB driver for atmel's AVRmicrocontrollers. New entries are always appended to the end of the file.Scroll down to the bottom to see the most recent changes.2005-04-01:  - Implemented endpoint 1 as interrupt-in endpoint.  - Moved all configuration options to usbconfig.h which is not part of the    driver.  - Changed interface for usbVendorSetup().  - Fixed compatibility with ATMega8 device.  - Various minor optimizations.2005-04-11:  - Changed interface to application: Use usbFunctionSetup(), usbFunctionRead()    and usbFunctionWrite() now. Added configuration options to choose which    of these functions to compile in.  - Assembler module delivers receive data non-inverted now.  - Made register and bit names compatible with more AVR devices.2005-05-03:  - Allow address of usbRxBuf on any memory page as long as the buffer does    not cross 256 byte page boundaries.  - Better device compatibility: works with Mega88 now.  - Code optimization in debugging module.  - Documentation updates.2006-01-02:  - Added (free) default Vendor- and Product-IDs bought from voti.nl.  - Added USBID-License.txt file which defines the rules for using the free    shared VID/PID pair.  - Added Readme.txt to the usbdrv directory which clarifies administrative    issues.2006-01-25:  - Added "configured state" to become more standards compliant.  - Added "HALT" state for interrupt endpoint.  - Driver passes the "USB Command Verifier" test from usb.org now.  - Made "serial number" a configuration option.  - Minor optimizations, we now recommend compiler option "-Os" for best    results.  - Added a version number to usbdrv.h2006-02-03:  - New configuration variable USB_BUFFER_SECTION for the memory section where    the USB rx buffer will go. This defaults to ".bss" if not defined. Since    this buffer MUST NOT cross 256 byte pages (not even touch a page at the    end), the user may want to pass a linker option similar to    "-Wl,--section-start=.mybuffer=0x800060".  - Provide structure for usbRequest_t.  - New defines for USB constants.  - Prepared for HID implementations.  - Increased data size limit for interrupt transfers to 8 bytes.  - New macro usbInterruptIsReady() to query interrupt buffer state.2006-02-18:  - Ensure that the data token which is sent as an ack to an OUT transfer is    always zero sized. This fixes a bug where the host reports an error after    sending an out transfer to the device, although all data arrived at the    device.  - Updated docs in usbdrv.h to reflect changed API in usbFunctionWrite().* Release 2006-02-20  - Give a compiler warning when compiling with debugging turned on.  - Added Oleg Semyonov's changes for IAR-cc compatibility.  - Added new (optional) functions usbDeviceConnect() and usbDeviceDisconnect()    (also thanks to Oleg!).  - Rearranged tests in usbPoll() to save a couple of instructions in the most    likely case that no actions are pending.  - We need a delay between the SET ADDRESS request until the new address    becomes active. This delay was handled in usbPoll() until now. Since the    spec says that the delay must not exceed 2ms, previous versions required    aggressive polling during the enumeration phase. We have now moved the    handling of the delay into the interrupt routine.  - We must not reply with NAK to a SETUP transaction. We can only achieve this    by making sure that the rx buffer is empty when SETUP tokens are expected.    We therefore don't pass zero sized data packets from the status phase of    a transfer to usbPoll(). This change MAY cause troubles if you rely on    receiving a less than 8 bytes long packet in usbFunctionWrite() to    identify the end of a transfer. usbFunctionWrite() will NEVER be called    with a zero length.* Release 2006-03-14  - Improved IAR C support: tiny memory model, more devices  - Added template usbconfig.h file under the name usbconfig-prototype.h* Release 2006-03-26  - Added provision for one more interrupt-in endpoint (endpoint 3).  - Added provision for one interrupt-out endpoint (endpoint 1).  - Added flowcontrol macros for USB.  - Added provision for custom configuration descriptor.  - Allow ANY two port bits for D+ and D-.  - Merged (optional) receive endpoint number into global usbRxToken variable.  - Use USB_CFG_IOPORTNAME instead of USB_CFG_IOPORT. We now construct the    variable name from the single port letter instead of computing the address    of related ports from the output-port address.* Release 2006-06-26  - Updated documentation in usbdrv.h and usbconfig-prototype.h to reflect the    new features.  - Removed "#warning" directives because IAR does not understand them. Use    unused static variables instead to generate a warning.  - Do not include <avr/io.h> when compiling with IAR.  - Introduced USB_CFG_DESCR_PROPS_* in usbconfig.h to configure how each    USB descriptor should be handled. It is now possible to provide descriptor    data in Flash, RAM or dynamically at runtime.  - STALL is now a status in usbTxLen* instead of a message. We can now conform    to the spec and leave the stall status pending until it is cleared.  - Made usbTxPacketCnt1 and usbTxPacketCnt3 public. This allows the    application code to reset data toggling on interrupt pipes.* Release 2006-07-18  - Added an #if !defined __ASSEMBLER__ to the warning in usbdrv.h. This fixes    an assembler error.  - usbDeviceDisconnect() takes pull-up resistor to high impedance now.* Release 2007-02-01  - Merged in some code size improvements from usbtiny (thanks to Dick    Streefland for these optimizations!)  - Special alignment requirement for usbRxBuf not required any more. Thanks    again to Dick Streefland for this hint!  - Reverted to "#warning" instead of unused static variables -- new versions    of IAR CC should handle this directive.  - Changed Open Source license to GNU GPL v2 in order to make linking against    other free libraries easier. We no longer require publication of the    circuit diagrams, but we STRONGLY encourage it. If you improve the driver    itself, PLEASE grant us a royalty free license to your changes for our    commercial license.* Release 2007-03-29  - New configuration option "USB_PUBLIC" in usbconfig.h.  - Set USB version number to 1.10 instead of 1.01.  - Code used USB_CFG_DESCR_PROPS_STRING_DEVICE and    USB_CFG_DESCR_PROPS_STRING_PRODUCT inconsistently. Changed all occurrences    to USB_CFG_DESCR_PROPS_STRING_PRODUCT.  - New assembler module for 16.5 MHz RC oscillator clock with PLL in receiver    code.  - New assembler module for 16 MHz crystal.  - usbdrvasm.S contains common code only, clock-specific parts have been moved    to usbdrvasm12.S, usbdrvasm16.S and usbdrvasm165.S respectively.* Release 2007-06-25  - 16 MHz module: Do SE0 check in stuffed bits as well.* Release 2007-07-07  - Define hi8(x) for IAR compiler to limit result to 8 bits. This is necessary    for negative values.  - Added 15 MHz module contributed by V. Bosch.  - Interrupt vector name can now be configured. This is useful if somebody    wants to use a different hardware interrupt than INT0.* Release 2007-08-07  - Moved handleIn3 routine in usbdrvasm16.S so that relative jump range is    not exceeded.  - More config options: USB_RX_USER_HOOK(), USB_INITIAL_DATATOKEN,    USB_COUNT_SOF  - USB_INTR_PENDING can now be a memory address, not just I/O* Release 2007-09-19  - Split out common parts of assembler modules into separate include file  - Made endpoint numbers configurable so that given interface definitions    can be matched. See USB_CFG_EP3_NUMBER in usbconfig-prototype.h.  - Store endpoint number for interrupt/bulk-out so that usbFunctionWriteOut()    can handle any number of endpoints.  - Define usbDeviceConnect() and usbDeviceDisconnect() even if no    USB_CFG_PULLUP_IOPORTNAME is defined. Directly set D+ and D- to 0 in this    case.* Release 2007-12-01  - Optimize usbDeviceConnect() and usbDeviceDisconnect() for less code size    when USB_CFG_PULLUP_IOPORTNAME is not defined.* Release 2007-12-13  - Renamed all include-only assembler modules from *.S to *.inc so that    people don't add them to their project sources.  - Distribute leap bits in tx loop more evenly for 16 MHz module.  - Use "macro" and "endm" instead of ".macro" and ".endm" for IAR  - Avoid compiler warnings for constant expr range by casting some values in    USB descriptors.* Release 2008-01-21