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##
## 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': 50, 'max': 90},
'RESPONSE HIGH' : {'min': 50, '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/DHTxx'
longname = 'Aosong AM230x/DHTxx'
desc = 'Aosong AM230x/DHTxx humidity/temperature sensor protocol.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['am230x']
channels = (
{'id': 'sda', 'name': 'SDA', 'desc': 'Single wire serial data line'},
)
options = (
{'id': 'device', 'desc': 'Device type',
'default': 'am230x', 'values': ('am230x', 'dht11')},
)
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(len(bitlist)):
number += bitlist[-1 - i] * 2**i
return number
def calculate_humidity(self, bitlist):
h = 0
if self.options['device'] == 'dht11':
h = self.bits2num(bitlist[0:8])
else:
h = self.bits2num(bitlist) / 10
return h
def calculate_temperature(self, bitlist):
t = 0
if self.options['device'] == 'dht11':
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 handle_byte(self, bit):
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)
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()
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.handle_byte(bit)
elif self.state == 'WAIT FOR END':
if sda != 1:
continue
self.putfs([3, ['End', 'E']])
self.reset()
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