Add decoder for AM230x digital humidity and temperature sensors.

2 files changed, 267 insertions, 0 deletions

diff --git a/decoders/am230x/__init__.py b/decoders/am230x/__init__.py
new file mode 100644
index 0000000..84e36c2
--- /dev/null
+++ b/decoders/am230x/__init__.py
@@ -0,0 +1,35 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Johannes Roemer <jroemer@physik.uni-wuerzburg.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
+##
+
+'''
+This decoder handles the proprietary single wire communication protocol used by
+the AM230x series of digital humidity and temperature sensors.
+
+Sample rate:
+A sample rate of at least 200 kHz is recommended to properly detect all the
+elements of the protocol.
+
+Options:
+The DHT11 digital humidity and temperature sensor uses the same single wire
+protocol with a different encoding of the measured values. Therefore the option
+'dht11' must be used to properly decode the communication of a DHT11 device.
+'''
+
+from .pd import *
diff --git a/decoders/am230x/pd.py b/decoders/am230x/pd.py
new file mode 100644
index 0000000..05489d9
--- /dev/null
+++ b/decoders/am230x/pd.py
@@ -0,0 +1,232 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Johannes Roemer <jroemer@physik.uni-wuerzburg.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
+##
+
+import sigrokdecode as srd
+
+# Define valid timing values (in microseconds).
+timing = {
+    'START LOW'     : {'min': 750, 'max': 25000},
+    'START HIGH'    : {'min': 10, 'max': 10000},
+    'RESPONSE LOW'  : {'min': 70, 'max': 90},
+    'RESPONSE HIGH' : {'min': 70, 'max': 90},
+    'BIT LOW'       : {'min': 45, 'max': 90},
+    'BIT 0 HIGH'    : {'min': 20, 'max': 35},
+    'BIT 1 HIGH'    : {'min': 65, 'max': 80},
+}
+
+class SamplerateError(Exception):
+    pass
+
+class Decoder(srd.Decoder):
+    api_version = 2
+    id = 'am230x'
+    name = 'AM230x'
+    longname = 'AM230x humidity and temperature sensors'
+    desc = 'Proprietary single wire communication bus.'
+    license = 'gplv2+'
+    inputs = ['logic']
+    outputs = ['am230x']
+    channels = (
+        {'id': 'sda', 'name': 'SDA', 'desc': 'Single wire serial data line'},
+    )
+    options = (
+        {'id': 'dht11', 'desc': 'DHT11 compatibility mode',
+            'default': 'no', 'values': ('no', 'yes')},
+    )
+    annotations = (
+        ('start', 'Start'),
+        ('response', 'Response'),
+        ('bit', 'Bit'),
+        ('end', 'End'),
+        ('byte', 'Byte'),
+        ('humidity', 'Relative humidity in percent'),
+        ('temperature', 'Temperature in degrees Celsius'),
+        ('checksum', 'Checksum'),
+    )
+    annotation_rows = (
+        ('bits', 'Bits', (0, 1, 2, 3)),
+        ('bytes', 'Bytes', (4,)),
+        ('results', 'Results', (5, 6, 7)),
+    )
+
+    def putfs(self, data):
+        self.put(self.fall, self.samplenum, self.out_ann, data)
+
+    def putb(self, data):
+        self.put(self.bytepos[-1], self.samplenum, self.out_ann, data)
+
+    def putv(self, data):
+        self.put(self.bytepos[-2], self.samplenum, self.out_ann, data)
+
+    def reset(self):
+        self.state = 'WAIT FOR START LOW'
+        self.samplenum = 0
+        self.fall = 0
+        self.rise = 0
+        self.bits = []
+        self.bytepos = []
+
+    def is_valid(self, name):
+        dt = 0
+        if name.endswith('LOW'):
+            dt = self.samplenum - self.fall
+        elif name.endswith('HIGH'):
+            dt = self.samplenum - self.rise
+        if dt >= self.cnt[name]['min'] and dt <= self.cnt[name]['max']:
+            return True
+        return False
+
+    def bits2num(self, bitlist):
+        number = 0
+        for i in range(0, len(bitlist)):
+            number += bitlist[-1-i] * 2**i
+        return number
+
+    def calculate_humidity(self, bitlist):
+        h = 0
+        if self.options['dht11'] == 'yes':
+            h = self.bits2num(bitlist[0:8])
+        else:
+            h = self.bits2num(bitlist) / 10
+        return h
+
+    def calculate_temperature(self, bitlist):
+        t = 0
+        if self.options['dht11'] == 'yes':
+            t = self.bits2num(bitlist[0:8])
+        else:
+            t = self.bits2num(bitlist[1:]) / 10
+            if bitlist[0] == 1:
+                t = -t
+        return t
+
+    def calculate_checksum(self, bitlist):
+        checksum = 0
+        for i in range(8, len(bitlist)+1, 8):
+            checksum += self.bits2num(bitlist[i-8:i])
+        return checksum % 256
+
+    def __init__(self, **kwargs):
+        self.samplerate = None
+        self.reset()
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def metadata(self, key, value):
+        if key != srd.SRD_CONF_SAMPLERATE:
+            return
+        self.samplerate = value
+        # Convert microseconds to sample counts.
+        self.cnt = {}
+        for e in timing:
+            self.cnt[e] = {}
+            for t in timing[e]:
+                self.cnt[e][t] = timing[e][t] * self.samplerate / 1000000
+
+    def decode(self, ss, es, data):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+        for (self.samplenum, (sda,)) in data:
+            # State machine.
+            if self.state == 'WAIT FOR START LOW':
+                if sda != 0:
+                    continue
+                self.fall = self.samplenum
+                self.state = 'WAIT FOR START HIGH'
+            elif self.state == 'WAIT FOR START HIGH':
+                if sda != 1:
+                    continue
+                if self.is_valid('START LOW'):
+                    self.rise = self.samplenum
+                    self.state = 'WAIT FOR RESPONSE LOW'
+                else:
+                    self.reset()
+            elif self.state == 'WAIT FOR RESPONSE LOW':
+                if sda != 0:
+                    continue
+                if self.is_valid('START HIGH'):
+                    self.putfs([0, ['Start', 'S']])
+                    self.fall = self.samplenum
+                    self.state = 'WAIT FOR RESPONSE HIGH'
+                else:
+                    self.reset()
+            elif self.state == 'WAIT FOR RESPONSE HIGH':
+                if sda != 1:
+                    continue
+                if self.is_valid('RESPONSE LOW'):
+                    self.rise = self.samplenum
+                    self.state = 'WAIT FOR FIRST BIT'
+                else:
+                    self.reset()
+            elif self.state == 'WAIT FOR FIRST BIT':
+                if sda != 0:
+                    continue
+                if self.is_valid('RESPONSE HIGH'):
+                    self.putfs([1, ['Response', 'R']])
+                    self.fall = self.samplenum
+                    self.bytepos.append(self.samplenum)
+                    self.state = 'WAIT FOR BIT HIGH'
+                else:
+                    self.reset_variables()
+            elif self.state == 'WAIT FOR BIT HIGH':
+                if sda != 1:
+                    continue
+                if self.is_valid('BIT LOW'):
+                    self.rise = self.samplenum
+                    self.state = 'WAIT FOR BIT LOW'
+                else:
+                    self.reset()
+            elif self.state == 'WAIT FOR BIT LOW':
+                if sda != 0:
+                    continue
+                if self.is_valid('BIT 0 HIGH'):
+                    bit = 0
+                elif self.is_valid('BIT 1 HIGH'):
+                    bit = 1
+                else:
+                    self.reset()
+                    continue
+                self.bits.append(bit)
+                self.putfs([2, ['Bit: %d' % bit, '%d' % bit]])
+                self.fall = self.samplenum
+                self.state = 'WAIT FOR BIT HIGH'
+                if len(self.bits) % 8 == 0:
+                    byte = self.bits2num(self.bits[-8:])
+                    self.putb([4, ['Byte: %#04x' % byte, '%#04x' % byte]])
+                    if len(self.bits) == 16:
+                        h = self.calculate_humidity(self.bits[-16:])
+                        self.putv([5, ['Humidity: %.1f %%' % h, 'RH = %.1f %%' % h]])
+                    elif len(self.bits) == 32:
+                        t = self.calculate_temperature(self.bits[-16:])
+                        self.putv([6, ['Temperature: %.1f °C' % t, 'T = %.1f °C' % t]])
+                    elif len(self.bits) == 40:
+                        parity = self.bits2num(self.bits[-8:])
+                        if parity == self.calculate_checksum(self.bits[0:32]):
+                            self.putb([7, ['Checksum: OK', 'OK']])
+                        else:
+                            self.putb([7, ['Checksum: not OK', 'NOK']])
+                        self.state = 'WAIT FOR END'
+                    self.bytepos.append(self.samplenum)
+            elif self.state == 'WAIT FOR END':
+                if sda != 1:
+                    continue
+                self.putfs([3, ['End', 'E']])
+                self.reset()