##
## This file is part of the libsigrokdecode project.
##
-## Copyright (C) 2010-2014 Uwe Hermann <uwe@hermann-uwe.de>
+## Copyright (C) 2010-2016 Uwe Hermann <uwe@hermann-uwe.de>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
-## along with this program; if not, write to the Free Software
-## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+## along with this program; if not, see <http://www.gnu.org/licenses/>.
##
# TODO: Look into arbitration, collision detection, clock synchronisation, etc.
'''
OUTPUT_PYTHON format:
-I²C packet:
-[<cmd>, <data>]
+Packet:
+[<ptype>, <pdata>]
-<cmd> is one of:
+<ptype>:
- 'START' (START condition)
- 'START REPEAT' (Repeated START condition)
- 'ADDRESS READ' (Slave address, read)
- 'STOP' (STOP condition)
- 'ACK' (ACK bit)
- 'NACK' (NACK bit)
- - 'BITS' (<data>: list of data/address bits and their ss/es numbers)
+ - 'BITS' (<pdata>: list of data/address bits and their ss/es numbers)
-<data> is the data or address byte associated with the 'ADDRESS*' and 'DATA*'
+<pdata> is the data or address byte associated with the 'ADDRESS*' and 'DATA*'
command. Slave addresses do not include bit 0 (the READ/WRITE indication bit).
For example, a slave address field could be 0x51 (instead of 0xa2).
-For 'START', 'START REPEAT', 'STOP', 'ACK', and 'NACK' <data> is None.
+For 'START', 'START REPEAT', 'STOP', 'ACK', and 'NACK' <pdata> is None.
'''
# CMD: [annotation-type-index, long annotation, short annotation]
'DATA WRITE': [9, 'Data write', 'DW'],
}
+class SamplerateError(Exception):
+ pass
+
class Decoder(srd.Decoder):
- api_version = 1
+ api_version = 3
id = 'i2c'
name = 'I²C'
longname = 'Inter-Integrated Circuit'
license = 'gplv2+'
inputs = ['logic']
outputs = ['i2c']
- probes = (
+ channels = (
{'id': 'scl', 'name': 'SCL', 'desc': 'Serial clock line'},
{'id': 'sda', 'name': 'SDA', 'desc': 'Serial data line'},
)
('data-write', 'Data write'),
)
- def __init__(self, **kwargs):
+ def __init__(self):
self.samplerate = None
- self.ss = self.es = self.byte_ss = -1
- self.samplenum = None
+ self.ss = self.es = self.ss_byte = -1
self.bitcount = 0
self.databyte = 0
self.wr = -1
self.is_repeat_start = 0
self.state = 'FIND START'
- self.oldscl = self.oldsda = 1
- self.oldpins = [1, 1]
self.pdu_start = None
self.pdu_bits = 0
self.bits = []
self.out_bitrate = self.register(srd.OUTPUT_META,
meta=(int, 'Bitrate', 'Bitrate from Start bit to Stop bit'))
+ # Assume that the initial SCL/SDA pin state is high (logic 1).
+ # This is a good default, since both pins have pullups as per spec.
+ self.initial_pins = [1, 1]
+
def putx(self, data):
self.put(self.ss, self.es, self.out_ann, data)
def putb(self, data):
self.put(self.ss, self.es, self.out_binary, data)
- 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 found_start(self, scl, sda):
+ def handle_start(self, pins):
self.ss, self.es = self.samplenum, self.samplenum
self.pdu_start = self.samplenum
self.pdu_bits = 0
self.bits = []
# Gather 8 bits of data plus the ACK/NACK bit.
- def found_address_or_data(self, scl, sda):
+ def handle_address_or_data(self, pins):
+ scl, sda = pins
+ self.pdu_bits += 1
+
# Address and data are transmitted MSB-first.
self.databyte <<= 1
self.databyte |= sda
# Remember the start of the first data/address bit.
if self.bitcount == 0:
- self.byte_ss = self.samplenum
+ self.ss_byte = self.samplenum
# Store individual bits and their start/end samplenumbers.
# In the list, index 0 represents the LSB (I²C transmits MSB-first).
cmd = 'DATA READ'
bin_class = 2
- self.ss, self.es = self.byte_ss, self.samplenum + self.bitwidth
+ self.ss, self.es = self.ss_byte, self.samplenum + self.bitwidth
self.putp(['BITS', self.bits])
self.putp([cmd, d])
- self.putb((bin_class, bytes([d])))
+ self.putb([bin_class, bytes([d])])
for bit in self.bits:
self.put(bit[1], bit[2], self.out_ann, [5, ['%d' % bit[0]]])
self.ss, self.es = self.samplenum, self.samplenum + self.bitwidth
w = ['Write', 'Wr', 'W'] if self.wr else ['Read', 'Rd', 'R']
self.putx([proto[cmd][0], w])
- self.ss, self.es = self.byte_ss, self.samplenum
+ self.ss, self.es = self.ss_byte, self.samplenum
self.putx([proto[cmd][0], ['%s: %02X' % (proto[cmd][1], d),
'%s: %02X' % (proto[cmd][2], d), '%02X' % d]])
self.bits = []
self.state = 'FIND ACK'
- def get_ack(self, scl, sda):
+ def get_ack(self, pins):
+ scl, sda = pins
self.ss, self.es = self.samplenum, self.samplenum + self.bitwidth
cmd = 'NACK' if (sda == 1) else 'ACK'
self.putp([cmd, None])
# another data byte or a STOP condition next.
self.state = 'FIND DATA'
- def found_stop(self, scl, sda):
+ def handle_stop(self, pins):
# Meta bitrate
elapsed = 1 / float(self.samplerate) * (self.samplenum - self.pdu_start + 1)
bitrate = int(1 / elapsed * self.pdu_bits)
- self.put(self.byte_ss, self.samplenum, self.out_bitrate, bitrate)
+ self.put(self.ss_byte, self.samplenum, self.out_bitrate, bitrate)
cmd = 'STOP'
self.ss, self.es = self.samplenum, self.samplenum
self.wr = -1
self.bits = []
- def decode(self, ss, es, data):
- if self.samplerate is None:
- raise Exception("Cannot decode without samplerate.")
- for (self.samplenum, pins) in data:
+ def decode(self):
+ if not self.samplerate:
+ raise SamplerateError('Cannot decode without samplerate.')
- # Ignore identical samples early on (for performance reasons).
- if self.oldpins == pins:
- continue
- self.oldpins, (scl, sda) = pins, pins
-
- self.pdu_bits += 1
+ self.wait({})
+ while True:
# State machine.
if self.state == 'FIND START':
- if self.is_start_condition(scl, sda):
- self.found_start(scl, sda)
+ # Wait for a START condition (S): SCL = high, SDA = falling.
+ self.handle_start(self.wait({0: 'h', 1: 'f'}))
elif self.state == 'FIND ADDRESS':
- if self.is_data_bit(scl, sda):
- self.found_address_or_data(scl, sda)
+ # Wait for a data bit: SCL = rising.
+ self.handle_address_or_data(self.wait({0: 'r'}))
elif self.state == 'FIND DATA':
- if self.is_data_bit(scl, sda):
- self.found_address_or_data(scl, sda)
- elif self.is_start_condition(scl, sda):
- self.found_start(scl, sda)
- elif self.is_stop_condition(scl, sda):
- self.found_stop(scl, sda)
+ # Wait for any of the following conditions (or combinations):
+ # a) Data sampling of receiver: SCL = rising, and/or
+ # b) START condition (S): SCL = high, SDA = falling, and/or
+ # c) STOP condition (P): SCL = high, SDA = rising
+ conds = [{0: 'r'}, {0: 'h', 1: 'f'}, {0: 'h', 1: 'r'}]
+ pins = self.wait(conds[:]) # TODO
+
+ # Check which of the condition(s) matched and handle them.
+ if self.matched[0]:
+ self.handle_address_or_data(pins)
+ elif self.matched[1]:
+ self.handle_start(pins)
+ elif self.matched[2]:
+ self.handle_stop(pins)
elif self.state == 'FIND ACK':
- if self.is_data_bit(scl, sda):
- self.get_ack(scl, sda)
- else:
- raise Exception('Invalid state: %s' % self.state)
-
- # Save current SDA/SCL values for the next round.
- self.oldscl, self.oldsda = scl, sda
-
+ # Wait for a data/ack bit: SCL = rising.
+ self.get_ack(self.wait({0: 'r'}))
projects / libsigrokdecode.git / blobdiff