diff options
Diffstat (limited to 'decoders')
| -rw-r--r-- | decoders/Makefile.am | 3 | ||||
| -rw-r--r-- | decoders/ddc.py | 74 | ||||
| -rw-r--r-- | decoders/i2c.py | 70 |
3 files changed, 102 insertions, 45 deletions
diff --git a/decoders/Makefile.am b/decoders/Makefile.am index 72987f4..c27d69f 100644 --- a/decoders/Makefile.am +++ b/decoders/Makefile.am @@ -28,7 +28,8 @@ dist_pkgdata_DATA = \ spi.py \ srd_usb.py \ transitioncounter.py \ - uart.py + uart.py \ + ddc.py CLEANFILES = *.pyc diff --git a/decoders/ddc.py b/decoders/ddc.py new file mode 100644 index 0000000..09f6844 --- /dev/null +++ b/decoders/ddc.py @@ -0,0 +1,74 @@ +## +## This file is part of the sigrok project. +## +## Copyright (C) 2012 Bert Vermeulen <bert@biot.com> +## +## 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 3 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, If not, see <http://www.gnu.org/licenses/>. +## + +# +# DDC protocol decoder +# +# This decoder extracts a DDC stream from an I2C session between a computer +# and a display device. The stream is output as plain bytes. +# + +import sigrokdecode + + +class Decoder(sigrokdecode.Decoder): + id = 'ddc' + name = 'DDC' + longname = 'Display Data Channel' + desc = 'DDC is a protocol for communication between computers and displays.' + longdesc = '' + author = 'Bert Vermeulen <bert@biot.com>' + license = 'gplv3+' + inputs = ['i2c'] + outputs = ['ddc'] + annotation = [ + ["Byte stream", "DDC byte stream as read from display."], + ] + + def __init__(self, **kwargs): + self.state = None + + def start(self, metadata): + self.output_annotation = self.add(sigrokdecode.SRD_OUTPUT_ANNOTATION, 'ddc') + + def decode(self, start_sample, end_sample, i2c_data): + try: + cmd, data, ack_bit = i2c_data + except Exception as e: + raise Exception("malformed I2C input: %s" % str(e)) from e + + if self.state is None: + # waiting for the DDC session to start + if cmd in ('START', 'START_REPEAT'): + self.state = 'start' + elif self.state == 'start': + if cmd == 'ADDRESS_READ' and data == 80: + # 80 is the I2C slave address of a connected display, + # so this marks the start of the DDC data transfer. + self.state = 'transfer' + elif cmd == 'STOP': + # back to idle + self.state = None + elif self.state == 'transfer': + if cmd == 'DATA_READ': + # there shouldn't be anything but data reads on this + # address, so ignore everything else + self.put(start_sample, end_sample, self.output_annotation, + [0, ["0x%.2x" % data]]) + diff --git a/decoders/i2c.py b/decoders/i2c.py index f098aff..08d0053 100644 --- a/decoders/i2c.py +++ b/decoders/i2c.py @@ -65,52 +65,41 @@ # 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) -# # TODO: I2C address of slaves. # TODO: Handle multiple different I2C devices on same bus # -> we need to decode multiple protocols at the same time. -# # -# I2C input format: +# I2C protocol output format: +# +# The protocol output consists of a (Python) list of I2C "packets", each of +# which is of the form +# +# [ _i2c_command_, _data_, _ack_bit_ ] +# +# _i2c_command_ is one of: +# - 'START' (START condition) +# - 'START_REPEAT' (Repeated START) +# - 'ADDRESS_READ' (Address, read) +# - 'ADDRESS_WRITE' (Address, write) +# - 'DATA_READ' (Data, read) +# - 'DATA_WRITE' (Data, write) +# - 'STOP' (STOP condition) # -# signals: -# [[id, channel, description], ...] # TODO +# _data_ is the data or address byte associated with the ADDRESS_* and DATA_* +# command. For START, START_REPEAT and STOP, this is None. # -# Example: -# {'id': 'SCL', 'ch': 5, 'desc': 'Serial clock line'} -# {'id': 'SDA', 'ch': 7, 'desc': 'Serial data line'} -# ... +# _ack_bit_ is either 'ACK' or 'NACK', but may also be None. # -# {'inbuf': [...], -# 'signals': [{'SCL': }]} # import sigrokdecode +# annotation feed formats +ANN_SHIFTED = 0 +ANN_SHIFTED_SHORT = 1 +ANN_RAW = 2 + # values are verbose and short annotation, respectively protocol = { 'START': ['START', 'S'], @@ -123,19 +112,12 @@ protocol = { 'DATA_READ': ['DATA READ', 'DR'], 'DATA_WRITE': ['DATA WRITE', 'DW'], } -# export protocol keys as symbols for i2c decoders up the stack -EXPORT = [ protocol.keys() ] # States FIND_START = 0 FIND_ADDRESS = 1 FIND_DATA = 2 -# annotation feed formats -ANN_SHIFTED = 0 -ANN_SHIFTED_SHORT = 1 -ANN_RAW = 2 - class Decoder(sigrokdecode.Decoder): id = 'i2c' @@ -209,7 +191,7 @@ class Decoder(sigrokdecode.Decoder): cmd = 'START_REPEAT' else: cmd = 'START' - self.put(self.output_protocol, [ cmd ]) + self.put(self.output_protocol, [ cmd, None, None ]) self.put(self.output_annotation, [ ANN_SHIFTED, [protocol[cmd][0]] ]) self.put(self.output_annotation, [ ANN_SHIFTED_SHORT, [protocol[cmd][1]] ]) @@ -269,7 +251,7 @@ class Decoder(sigrokdecode.Decoder): cmd = 'DATA_WRITE' elif self.state == FIND_DATA and self.wr == 0: cmd = 'DATA_READ' - self.put(self.output_protocol, [ [cmd, d], [ack_bit] ] ) + self.put(self.output_protocol, [ cmd, d, ack_bit ] ) self.put(self.output_annotation, [ANN_SHIFTED, [ "%s" % protocol[cmd][0], "0x%02x" % d, @@ -292,7 +274,7 @@ class Decoder(sigrokdecode.Decoder): pass def found_stop(self, scl, sda): - self.put(self.output_protocol, [ 'STOP' ]) + self.put(self.output_protocol, [ 'STOP', None, None ]) self.put(self.output_annotation, [ ANN_SHIFTED, [protocol['STOP'][0]] ]) self.put(self.output_annotation, [ ANN_SHIFTED_SHORT, [protocol['STOP'][1]] ]) |