## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
##
-# I2C protocol decoder
-
# TODO: Look into arbitration, collision detection, clock synchronisation, etc.
# TODO: Implement support for 10bit slave addresses.
# TODO: Implement support for inverting SDA/SCL levels (0->1 and 1->0).
import sigrokdecode as srd
'''
-Protocol output format:
+OUTPUT_PYTHON format:
-I2C packet:
+I²C packet:
[<cmd>, <data>]
<cmd> is one of:
class Decoder(srd.Decoder):
api_version = 1
id = 'i2c'
- name = 'I2C'
+ name = 'I²C'
longname = 'Inter-Integrated Circuit'
desc = 'Two-wire, multi-master, serial bus.'
license = 'gplv2+'
'address_format': ['Displayed slave address format', 'shifted'],
}
annotations = [
- ['Start', 'Start condition'],
- ['Repeat start', 'Repeat start condition'],
- ['Stop', 'Stop condition'],
- ['ACK', 'ACK'],
- ['NACK', 'NACK'],
- ['Address read', 'Address read'],
- ['Address write', 'Address write'],
- ['Data read', 'Data read'],
- ['Data write', 'Data write'],
- ['Warnings', 'Human-readable warnings'],
+ ['start', 'Start condition'],
+ ['repeat-start', 'Repeat start condition'],
+ ['stop', 'Stop condition'],
+ ['ack', 'ACK'],
+ ['nack', 'NACK'],
+ ['address-read', 'Address read'],
+ ['address-write', 'Address write'],
+ ['data-read', 'Data read'],
+ ['data-write', 'Data write'],
+ ['warnings', 'Human-readable warnings'],
]
+ binary = (
+ ('address-read', 'Address read'),
+ ('address-write', 'Address write'),
+ ('data-read', 'Data read'),
+ ('data-write', 'Data write'),
+ )
def __init__(self, **kwargs):
+ self.samplerate = None
self.startsample = -1
self.samplenum = None
self.bitcount = 0
self.oldscl = 1
self.oldsda = 1
self.oldpins = [1, 1]
+ self.pdu_start = None
+ self.pdu_bits = 0
- def start(self):
- self.out_proto = self.add(srd.OUTPUT_PROTO, 'i2c')
- self.out_ann = self.add(srd.OUTPUT_ANN, 'i2c')
+ def metadata(self, key, value):
+ if key == srd.SRD_CONF_SAMPLERATE:
+ self.samplerate = value
- def report(self):
- pass
+ def start(self):
+ self.out_python = self.register(srd.OUTPUT_PYTHON)
+ self.out_ann = self.register(srd.OUTPUT_ANN)
+ self.out_binary = self.register(srd.OUTPUT_BINARY)
+ self.out_bitrate = self.register(srd.OUTPUT_META,
+ meta=(int, 'Bitrate', 'Bitrate from Start bit to Stop bit'))
def putx(self, data):
self.put(self.startsample, self.samplenum, self.out_ann, data)
def putp(self, data):
- self.put(self.startsample, self.samplenum, self.out_proto, data)
+ self.put(self.startsample, self.samplenum, self.out_python, data)
+
+ def putb(self, data):
+ self.put(self.startsample, self.samplenum, self.out_binary, data)
def is_start_condition(self, scl, sda):
# START condition (S): SDA = falling, SCL = high
def found_start(self, scl, sda):
self.startsample = self.samplenum
+ self.pdu_start = self.samplenum
+ self.pdu_bits = 0
cmd = 'START REPEAT' if (self.is_repeat_start == 1) else 'START'
self.putp([cmd, None])
self.putx([proto[cmd][0], proto[cmd][1:]])
if self.options['address_format'] == 'shifted':
d = d >> 1
+ bin_class = -1
if self.state == 'FIND ADDRESS' and self.wr == 1:
cmd = 'ADDRESS WRITE'
+ bin_class = 1
elif self.state == 'FIND ADDRESS' and self.wr == 0:
cmd = 'ADDRESS READ'
+ bin_class = 0
elif self.state == 'FIND DATA' and self.wr == 1:
cmd = 'DATA WRITE'
+ bin_class = 3
elif self.state == 'FIND DATA' and self.wr == 0:
cmd = 'DATA READ'
+ bin_class = 2
self.putp([cmd, d])
self.putx([proto[cmd][0], ['%s: %02X' % (proto[cmd][1], d),
'%s: %02X' % (proto[cmd][2], d), '%02X' % d]])
+ self.putb((bin_class, bytes([d])))
# Done with this packet.
self.startsample = -1
self.state = 'FIND DATA'
def found_stop(self, scl, sda):
+ # Meta bitrate
+ elapsed = 1 / float(self.samplerate) * (self.samplenum - self.pdu_start + 1)
+ bitrate = int(1 / elapsed * self.pdu_bits)
+ self.put(self.startsample, self.samplenum, self.out_bitrate, bitrate)
+
self.startsample = self.samplenum
cmd = 'STOP'
self.putp([cmd, None])
self.wr = -1
def decode(self, ss, es, data):
+ if self.samplerate is None:
+ raise Exception("Cannot decode without samplerate.")
for (self.samplenum, pins) in data:
# Ignore identical samples early on (for performance reasons).
continue
self.oldpins, (scl, sda) = pins, pins
+ self.pdu_bits += 1
+
# TODO: Wait until the bus is idle (SDA = SCL = 1) first?
# State machine.