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Diffstat (limited to 'scripts/i2c.py')
| -rw-r--r-- | scripts/i2c.py | 255 |
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diff --git a/scripts/i2c.py b/scripts/i2c.py deleted file mode 100644 index bbf6925..0000000 --- a/scripts/i2c.py +++ /dev/null @@ -1,255 +0,0 @@ -## -## This file is part of the sigrok project. -## -## Copyright (C) 2010 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 -## the Free Software Foundation; either version 2 of the License, or -## (at your option) any later version. -## -## This program is distributed in the hope that it will be useful, -## but WITHOUT ANY WARRANTY; without even the implied warranty of -## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -## 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 -## - -# -# I2C protocol decoder -# - -# -# The Inter-Integrated Circuit (I2C) bus is a bidirectional, multi-master -# bus using two signals (SCL = serial clock line, SDA = serial data line). -# -# There can be many devices on the same bus. Each device can potentially be -# master or slave (and that can change during runtime). Both slave and master -# can potentially play the transmitter or receiver role (this can also -# change at runtime). -# -# Possible maximum data rates: -# - Standard mode: 100 kbit/s -# - Fast mode: 400 kbit/s -# - Fast-mode Plus: 1 Mbit/s -# - High-speed mode: 3.4 Mbit/s -# -# START condition (S): SDA = falling, SCL = high -# Repeated START condition (Sr): same as S -# STOP condition (P): SDA = rising, SCL = high -# -# All data bytes on SDA are exactly 8 bits long (transmitted MSB-first). -# Each byte has to be followed by a 9th ACK/NACK bit. If that bit is low, -# that indicates an ACK, if it's high that indicates a NACK. -# -# After the first START condition, a master sends the device address of the -# slave it wants to talk to. Slave addresses are 7 bits long (MSB-first). -# After those 7 bits, a data direction bit is sent. If the bit is low that -# indicates a WRITE operation, if it's high that indicates a READ operation. -# -# Later an optional 10bit slave addressing scheme was added. -# -# Documentation: -# http://www.nxp.com/acrobat/literature/9398/39340011.pdf (v2.1 spec) -# http://www.nxp.com/acrobat/usermanuals/UM10204_3.pdf (v3 spec) -# http://en.wikipedia.org/wiki/I2C -# - -# TODO: Look into arbitration, collision detection, clock synchronisation, etc. -# TODO: Handle clock stretching. -# TODO: Handle combined messages / repeated START. -# TODO: Implement support for 7bit and 10bit slave addresses. -# TODO: Implement support for inverting SDA/SCL levels (0->1 and 1->0). -# TODO: Implement support for detecting various bus errors. - -# -# I2C output format: -# -# The output consists of a (Python) list of I2C "packets", each of which -# has an (implicit) index number (its index in the list). -# Each packet consists of a Python dict with certain key/value pairs. -# -# TODO: Make this a list later instead of a dict? -# -# 'type': (string) -# - 'S' (START condition) -# - 'Sr' (Repeated START) -# - 'AR' (Address, read) -# - 'AW' (Address, write) -# - 'DR' (Data, read) -# - 'DW' (Data, write) -# - 'P' (STOP condition) -# 'range': (tuple of 2 integers, the min/max samplenumber of this range) -# - (min, max) -# - min/max can also be identical. -# 'data': (actual data as integer ???) TODO: This can be very variable... -# 'ann': (string; additional annotations / comments) -# -# Example output: -# [{'type': 'S', 'range': (150, 160), 'data': None, 'ann': 'Foobar'}, -# {'type': 'AW', 'range': (200, 300), 'data': 0x50, 'ann': 'Slave 4'}, -# {'type': 'DW', 'range': (310, 370), 'data': 0x00, 'ann': 'Init cmd'}, -# {'type': 'AR', 'range': (500, 560), 'data': 0x50, 'ann': 'Get stat'}, -# {'type': 'DR', 'range': (580, 640), 'data': 0xfe, 'ann': 'OK'}, -# {'type': 'P', 'range': (650, 660), 'data': None, 'ann': None}] -# -# Possible other events: -# - Error event in case protocol looks broken: -# [{'type': 'ERROR', 'range': (min, max), -# 'data': TODO, 'ann': 'This is not a Microchip 24XX64 EEPROM'}, -# [{'type': 'ERROR', 'range': (min, max), -# 'data': TODO, 'ann': 'TODO'}, -# - TODO: Make list of possible errors accessible as metadata? -# -# TODO: I2C address of slaves. -# TODO: Handle multiple different I2C devices on same bus -# -> we need to decode multiple protocols at the same time. -# TODO: range: Always contiguous? Splitted ranges? Multiple per event? -# - -# -# I2C input format: -# -# signals: -# [[id, channel, description], ...] # TODO -# -# Example: -# {'id': 'SCL', 'ch': 5, 'desc': 'Serial clock line'} -# {'id': 'SDA', 'ch': 7, 'desc': 'Serial data line'} -# ... -# -# {'inbuf': [...], -# 'signals': [{'SCL': }]} -# - -def decode(inbuf): - """I2C protocol decoder""" - - # FIXME: Get the data in the correct format in the first place. - inbuf = [ord(x) for x in inbuf] - - # FIXME: This should be passed in as metadata, not hardcoded here. - metadata = { - 'numchannels': 8, - 'signals': { - 'scl': {'ch': 5, 'name': 'SCL', 'desc': 'Serial clock line'}, - 'sda': {'ch': 7, 'name': 'SDA', 'desc': 'Serial data line'}, - }, - } - - out = [] - o = ack = d = '' - bitcount = data = 0 - wr = startsample = -1 - IDLE, START, ADDRESS, DATA = range(4) - state = IDLE - - # Get the channel/probe number of the SCL/SDA signals. - scl_bit = metadata['signals']['scl']['ch'] - sda_bit = metadata['signals']['sda']['ch'] - - # Get SCL/SDA bit values (0/1 for low/high) of the first sample. - s = inbuf[0] - oldscl = (s & (1 << scl_bit)) >> scl_bit - oldsda = (s & (1 << sda_bit)) >> sda_bit - - # Loop over all samples. - # TODO: Handle LAs with more/less than 8 channels. - for samplenum, s in enumerate(inbuf[1:]): # We skip the first byte... - # Get SCL/SDA bit values (0/1 for low/high). - scl = (s & (1 << scl_bit)) >> scl_bit - sda = (s & (1 << sda_bit)) >> sda_bit - - # TODO: Wait until the bus is idle (SDA = SCL = 1) first? - - # START condition (S): SDA = falling, SCL = high - if (oldsda == 1 and sda == 0) and scl == 1: - o = {'type': 'S', 'range': (samplenum, samplenum), - 'data': None, 'ann': None}, - out.append(o) - state = ADDRESS - bitcount = data = 0 - - # Data latching by transmitter: SCL = low - elif (scl == 0): - pass # TODO - - # Data sampling of receiver: SCL = rising - elif (oldscl == 0 and scl == 1): - if startsample == -1: - startsample = samplenum - bitcount += 1 - - # out.append("%d\t\tRECEIVED BIT %d: %d\n" % \ - # (samplenum, 8 - bitcount, sda)) - - # Address and data are transmitted MSB-first. - data <<= 1 - data |= sda - - if bitcount != 9: - continue - - # We received 8 address/data bits and the ACK/NACK bit. - data >>= 1 # Shift out unwanted ACK/NACK bit here. - ack = (sda == 1) and 'N' or 'A' - d = (state == ADDRESS) and (data & 0xfe) or data - if state == ADDRESS: - wr = (data & 1) and 1 or 0 - state = DATA - o = {'type': state, - 'range': (startsample, samplenum - 1), - 'data': d, 'ann': None} - if state == ADDRESS and wr == 1: - o['type'] = 'AW' - elif state == ADDRESS and wr == 0: - o['type'] = 'AR' - elif state == DATA and wr == 1: - o['type'] = 'DW' - elif state == DATA and wr == 0: - o['type'] = 'DR' - out.append(o) - o = {'type': ack, 'range': (samplenum, samplenum), - 'data': None, 'ann': None} - out.append(o) - bitcount = data = startsample = 0 - startsample = -1 - - # STOP condition (P): SDA = rising, SCL = high - elif (oldsda == 0 and sda == 1) and scl == 1: - o = {'type': 'P', 'range': (samplenum, samplenum), - 'data': None, 'ann': None}, - out.append(o) - state = IDLE - wr = -1 - - # Save current SDA/SCL values for the next round. - oldscl = scl - oldsda = sda - - # FIXME: Just for testing... - return str(out) - -def register(): - return { - 'id': 'i2c', - 'name': 'I2C', - 'desc': 'Inter-Integrated Circuit (I2C) bus', - 'inputformats': ['raw'], - 'signalnames': { - 'SCL': 'Serial clock line', - 'SDA': 'Serial data line', - }, - 'outputformats': ['i2c'], - } - -# Use psyco (if available) as it results in huge performance improvements. -try: - import psyco - psyco.bind(decode) -except ImportError: - pass - |