# avrdoper.py - Copyright (c) 2007 Kai Morich (www.kai-morich.de)## a pyserial like interface to the AVR-doper internal UART# implements a subset of pyserial( http://pyserial.sourceforge.net)# requires pyusb (http://pyusb.sourceforge.net) which uses libusb(-win32)## This file is distributed under the MIT License:# # Permission is hereby granted, free of charge, to any person# obtaining a copy of this software and associated documentation# files (the "Software"), to deal in the Software without# restriction, including without limitation the rights to use,# copy, modify, merge, publish, distribute, sublicense, and/or sell# copies of the Software, and to permit persons to whom the# Software is furnished to do so, subject to the following# conditions:# # The above copyright notice and this permission notice shall be# included in all copies or substantial portions of the Software.# # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR# OTHER DEALINGS IN THE SOFTWARE.# Note:# the AVR-doper internal UART is slower than a native UART.# writing data at 19200 baud was 325 vs. 1350 bytes/sec.import timeimport usb class SerialException(Exception):    passclass Serial:    __VENDOR_RQ_WRITE=1    __VENDOR_RQ_READ=2    def __init__(self, timeout=None, poll=.02):        """AVR-Doper internal UART. port is immediately opened"""        # timeout like pyserial. port is fixed to 19200,8,N,1.        # all other pyserial parameters are not applicable        # poll is sleep interval in timeout handling        self.timeout=timeout        self.poll=poll        self.handle=None        self.open()    def open(self):        if self.handle:            return        for bus in usb.busses():            for dev in bus.devices:                if dev.idVendor==0x16c0 and dev.idProduct in (0x05e1,0x05df):                    handle=dev.open()                    if handle.getString(dev.iManufacturer, 256)=='obdev.at' and \                       handle.getString(dev.iProduct, 256)=='AVR-Doper':                        self.handle=handle        if not self.handle:            raise SerialException('AVR-Doper not found')    def close(self):        if self.handle:            del self.handle            self.handle=None    def write(self, buffer):        for c in buffer:            self.handle.controlMsg(usb.TYPE_VENDOR|usb.RECIP_DEVICE|usb.ENDPOINT_OUT,                                        self.__VENDOR_RQ_WRITE, None, ord(c), 0)            def read(self, size=1):        if self.timeout: t0=time.time()            res=''        while 1:            buffer = self.handle.controlMsg(usb.TYPE_VENDOR|usb.RECIP_DEVICE|usb.ENDPOINT_IN,                                             self.__VENDOR_RQ_READ, size-len(res), 0, 0)            for b in buffer:                res+=chr(b<0 and 256+b or b)            if len(res)==size or self.timeout==0 or (self.timeout!=None and time.time()-t0>self.timeout):                break # calculate own timeout because controlMsg ignores usb timeout            if not buffer:                time.sleep(self.poll)        return res    def readline(self):        line=''        while 1:            c=self.read(1)            if not c: break            line+=c            if c=='\n': break        return line    def flushInput(self):        """read and discard AVR-Doper serial buffer"""        while self.handle.controlMsg(usb.TYPE_VENDOR|usb.RECIP_DEVICE|usb.ENDPOINT_IN,                                     self.__VENDOR_RQ_READ, 1, 0, 0):            pass    def flushOutput(self):        """there is no accessible output buffer"""        passdef test():    """whatever you want to send/recieve"""    s=Serial(timeout=0.1)    for i in range(5):        s.write('u\n')        print '<',s.readline(),if __name__ == '__main__':    test()