## ## This file is part of the libsigrokdecode project. ## ## Copyright (C) 2014 Johannes Roemer ## ## 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 = 3 id = 'am230x' name = 'AM230x/DHTxx/RHTxx' longname = 'Aosong AM230x/DHTxx/RHTxx' desc = 'Aosong AM230x/DHTxx/RHTxx 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/rht', '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.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): self.samplerate = None self.reset() def start(self): self.out_ann = self.register(srd.OUTPUT_ANN) # Assume that the initial pin state is high (logic 1). self.initial_pins = [1] 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): if not self.samplerate: raise SamplerateError('Cannot decode without samplerate.') while True: # State machine. if self.state == 'WAIT FOR START LOW': self.wait({0: 'f'}) self.fall = self.samplenum self.state = 'WAIT FOR START HIGH' elif self.state == 'WAIT FOR START HIGH': self.wait({0: 'r'}) 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': self.wait({0: 'f'}) 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': self.wait({0: 'r'}) 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': self.wait({0: 'f'}) 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': self.wait({0: 'r'}) 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': self.wait({0: 'f'}) 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': self.wait({0: 'r'}) self.putfs([3, ['End', 'E']]) self.reset()