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comparison usb488.py @ 1:e2089824735a

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Make the read support work properly & check what the device gives us. - Comment out debugging. - Stringify result. - Handle >1 packet reads (theoretically). - Validate returned packet.
author Daniel O'Connor <darius@dons.net.au>
date Wed, 13 May 2009 15:02:09 +0930
parents a43a47dfc902
children adaff1c4fd6b
comparison
equal deleted inserted replaced
0:a43a47dfc902 1:e2089824735a
165 if self.tag == 0: 165 if self.tag == 0:
166 self.tag += 1 166 self.tag += 1
167 167
168 def write(self, data): 168 def write(self, data):
169 """Send data (string) to the scope""" 169 """Send data (string) to the scope"""
170
170 orddata = map(ord, data) 171 orddata = map(ord, data)
172 # The device needs a \n at the end, enfore this
173 if orddata[-1] != '\n':
174 orddata += [ord('\n')]
171 datalen = len(orddata) 175 datalen = len(orddata)
172 176
173 # Build the packet 177 # Build the packet
174 pkt = [ DEV_DEP_MSG_OUT, self.tag, ~self.tag & 0xff, 0x00, 178 pkt = [ DEV_DEP_MSG_OUT, self.tag, ~self.tag & 0xff, 0x00,
175 datalen & 0xff, datalen >> 8 & 0xff, datalen >> 16 & 0xff, 179 datalen & 0xff, datalen >> 8 & 0xff, datalen >> 16 & 0xff,
188 # Split it up into maxPacket sized chunks and send.. 192 # Split it up into maxPacket sized chunks and send..
189 while len(pkt) > 0: 193 while len(pkt) > 0:
190 chunk = pkt[0:self.maxPacket] 194 chunk = pkt[0:self.maxPacket]
191 pkt = pkt[self.maxPacket:] 195 pkt = pkt[self.maxPacket:]
192 196
193 print "Sending %s bytes of data: %s" % (len(chunk), chunk) 197 #print "Sending %s bytes of data: %s" % (len(chunk), chunk)
194 wrote = self.handle.bulkWrite(self.bulkoutep, chunk) 198 wrote = self.handle.bulkWrite(self.bulkoutep, chunk)
195 if wrote != len(chunk): 199 if wrote != len(chunk):
196 raise "Short write, got %d, expected %d" % (wrote, len(chunk)) 200 raise "Short write, got %d, expected %d" % (wrote, len(chunk))
197 201
198 def read(self): 202 def read(self):
199 """Read data from the device""" 203 """Read data from the device"""
200 204
201 205 # Maximum we accept at once
202 datalen = 1024 206 # Was 2^31 - 1 but that seems to make things take too long to
203 # Ask the device to send us something 207 # read (perhaps libusb tries to malloc it..)
204 pkt = [ REQUEST_DEV_DEP_MSG_IN, self.tag, ~self.tag & 0xff, 0x00, 208 datalen = 10240
205 datalen & 0xff, datalen >> 8 & 0xff, datalen >> 16 & 0xff, 209 data = []
206 datalen >> 24 & 0xff, 0, 0, 0, 0]
207
208 # Bump tag
209 self.incrtag()
210
211 # Send it
212 wrote = self.handle.bulkWrite(self.bulkoutep, pkt)
213 if wrote != len(pkt):
214 print "Short write, got %d, expected %d" % (wrote, len(pkt))
215
216 read = self.handle.bulkRead(self.bulkinep, datalen)
217 print "Read %s bytes: %s" % (len(read), str(read))
218 return read
219 210
211 while True:
212 # Ask the device to send us something
213 pkt = [ REQUEST_DEV_DEP_MSG_IN, self.tag, ~self.tag & 0xff, 0x00,
214 datalen & 0xff, datalen >> 8 & 0xff, datalen >> 16 & 0xff,
215 datalen >> 24 & 0xff, 0, 0, 0, 0]
216
217 # Expected tag
218 exptag = self.tag
219
220 # Bump tag
221 self.incrtag()
222
223 # Send it
224 #print "Sending " + str(pkt)
225 wrote = self.handle.bulkWrite(self.bulkoutep, pkt)
226 if wrote != len(pkt):
227 print "Short write, got %d, expected %d" % (wrote, len(pkt))
228
229 #print "Reading.."
230 read = self.handle.bulkRead(self.bulkinep, datalen)
231 #print "Read %s bytes: %s" % (len(read), str(read))
232
233 if read[0] != DEV_DEP_MSG_IN:
234 raise "Unexpected Msg ID, got %s expected %d" % (read[0], DEV_DEP_MSG_IN)
235 if read[1] != exptag:
236 raise "Unexpected tag, got %d expected %d" % (read[1], exptag)
237 if read[2] != ~exptag & 0xff:
238 raise "Unexpected tag inverse, got %d expected %d" % (read[1], ~exptag & 0xff)
239
240 actualdata = read[4] | read[5] << 8 | read[6] << 16 | read[7] << 24
241 #print "Computed datalen is %d" % (actualdata)
242 data += read[12:12 + actualdata]
243 if read[8] & 0x01:
244 #print "Breaking out due to EOM"
245 break
246
247 # Stringify result for easier consumption
248 result = reduce(lambda x, y: x+y, map(chr, data))
249 # Trim off \n if present
250 if result[-1] == '\n':
251 result = result[0:-1]
252
253 return result
254
220 def find488(): 255 def find488():
221 """Search for a USB488 device, returns a handle, iface, dev tuple for it""" 256 """Search for a USB488 device, returns a handle, iface, dev tuple for it"""
222 257
223 busses = usb.busses() 258 busses = usb.busses()
224 259