Add LTC242x decoder.

Signed-off-by: Teo Perisanu <redacted>

diff --git a/decoders/ltc242x/__init__.py b/decoders/ltc242x/__init__.py
new file mode 100644 (file)
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+++ b/decoders/ltc242x/__init__.py
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+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2020 Analog Devices Inc.
+##
+## 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, see <http://www.gnu.org/licenses/>.
+##
+
+'''
+This decoder stacks on top of the 'spi' PD and decodes the
+Linear Technology LTC2421/LTC2422 protocol.
+'''
+
+from .pd import Decoder

diff --git a/decoders/ltc242x/pd.py b/decoders/ltc242x/pd.py
new file mode 100644 (file)
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+++ b/decoders/ltc242x/pd.py
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+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2020 Analog Devices Inc.
+##
+## 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, see <http://www.gnu.org/licenses/>.
+##
+
+import sigrokdecode as srd
+
+channel_format = ['Channel %d', 'Ch %d', '%d']
+input_voltage_format = ['%fV', '%fV', '%.6fV', '%.2fV']
+
+class Decoder(srd.Decoder):
+    api_version = 3
+    id = 'ltc242x'
+    name = 'LTC242x'
+    longname = 'Linear Technology LTC242x'
+    desc = 'Linear Technology LTC2421/LTC2422 1-/2-channel 20-bit ADC.'
+    license = 'gplv2+'
+    inputs = ['spi']
+    outputs = []
+    tags = ['Display']
+    annotations = (
+        ('channel', 'Channel'),
+        ('input', 'Input voltage'),
+    )
+    annotation_rows = (
+        ('channel', 'Channel', (0,)),
+        ('input', 'Input voltage', (1,)),
+    )
+    options = (
+        {'id': 'ref', 'desc': 'Reference voltage', 'default': 1.5},
+    )
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.data = 0
+        self.ss, self.es = 0, 0
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def handle_channel(self, data):
+        channel = (data & (1 << 22)) >> 22
+        ann = []
+        for format in channel_format:
+            ann.append(format % channel)
+
+        self.put(self.ss, self.es, self.out_ann, [0, ann])
+
+    def handle_input_voltage(self, data):
+        input_voltage = data & 0x3FFFFF
+        input_voltage = -(2**21 - input_voltage)
+        input_voltage = (input_voltage / 0xfffff) * self.options['ref']
+        ann = []
+        for format in input_voltage_format:
+            ann.append(format % input_voltage)
+
+        self.put(self.ss, self.es, self.out_ann, [1, ann])
+
+    def decode(self, ss, es, data):
+        ptype = data[0]
+
+        if ptype == 'CS-CHANGE':
+            cs_old, cs_new = data[1:]
+            if cs_old is not None and cs_old == 0 and cs_new == 1:
+                self.es = es
+                self.data >>= 1
+                self.handle_channel(self.data)
+                self.handle_input_voltage(self.data)
+
+                self.data = 0
+            elif cs_old is not None and cs_old == 1 and cs_new == 0:
+                self.ss = ss
+
+        elif ptype == 'BITS':
+            miso = data[2]
+            for bit in reversed(miso):
+                self.data = self.data | bit[0]
+
+                self.data <<= 1