+ def is_start_condition(self, scl, sda):
+ '''START condition (S): SDA = falling, SCL = high'''
+ if (self.oldsda == 1 and sda == 0) and scl == 1:
+ return True
+ return False
+
+ def is_data_bit(self, scl, sda):
+ '''Data sampling of receiver: SCL = rising'''
+ if self.oldscl == 0 and scl == 1:
+ return True
+ return False
+
+ def is_stop_condition(self, scl, sda):
+ '''STOP condition (P): SDA = rising, SCL = high'''
+ if (self.oldsda == 0 and sda == 1) and scl == 1:
+ return True
+ return False
+
+ def find_start(self, scl, sda):
+ out = []
+ # o = {'type': 'S', 'range': (self.samplenum, self.samplenum),
+ # 'data': None, 'ann': None},
+ o = 'S'
+ out.append(o)
+ self.state = self.FIND_ADDRESS
+ self.bitcount = self.databyte = 0
+ self.wr = -1
+ return out
+
+ def find_address_or_data(self, scl, sda):
+ '''Gather 8 bits of data plus the ACK/NACK bit.'''
+ out = o = []
+
+ if self.startsample == -1:
+ self.startsample = self.samplenum
+ self.bitcount += 1
+
+ # Address and data are transmitted MSB-first.
+ self.databyte <<= 1
+ self.databyte |= sda
+
+ # Return if we haven't collected all 8 + 1 bits, yet.
+ if self.bitcount != 9:
+ return []
+
+ # We received 8 address/data bits and the ACK/NACK bit.
+ self.databyte >>= 1 # Shift out unwanted ACK/NACK bit here.
+
+ ack = (sda == 1) and 'N' or 'A'
+
+ if self.state == self.FIND_ADDRESS:
+ d = self.databyte & 0xfe
+ # The READ/WRITE bit is only in address bytes, not data bytes.
+ self.wr = (self.databyte & 1) and 1 or 0
+ elif self.state == self.FIND_DATA:
+ d = self.databyte
+ else:
+ # TODO: Error?
+ pass
+
+ # o = {'type': self.state,
+ # 'range': (self.startsample, self.samplenum - 1),
+ # 'data': d, 'ann': None}
+
+ o = {'data': "0x%02x" % d}
+
+ # TODO: Simplify.
+ if self.state == self.FIND_ADDRESS and self.wr == 1:
+ o['type'] = 'AW'
+ elif self.state == self.FIND_ADDRESS and self.wr == 0:
+ o['type'] = 'AR'
+ elif self.state == self.FIND_DATA and self.wr == 1:
+ o['type'] = 'DW'
+ elif self.state == self.FIND_DATA and self.wr == 0:
+ o['type'] = 'DR'
+
+ out.append(o)
+
+ # o = {'type': ack, 'range': (self.samplenum, self.samplenum),
+ # 'data': None, 'ann': None}
+ o = ack
+ out.append(o)
+ self.bitcount = self.databyte = 0
+ self.startsample = -1
+
+ if self.state == self.FIND_ADDRESS:
+ self.state = self.FIND_DATA
+ elif self.state == self.FIND_DATA:
+ # There could be multiple data bytes in a row.
+ # So, either find a STOP condition or another data byte next.
+ pass
+
+ return out
+
+ def find_stop(self, scl, sda):
+ out = o = []
+
+ # o = {'type': 'P', 'range': (self.samplenum, self.samplenum),
+ # 'data': None, 'ann': None},
+ o = 'P'
+ out.append(o)
+ self.state = self.FIND_START
+ self.wr = -1
+
+ return out
+