from .lists import *
import sigrokdecode as srd
+# Concentrate all timing constraints of the IR protocol here in a single
+# location at the top of the source, to raise awareness and to simplify
+# review and adjustment. The tolerance is an arbitrary choice, available
+# literature does not mention any. The inter-frame timeout is not a part
+# of the protocol, but an implementation detail of this sigrok decoder.
+_TIME_TOL = 8 # tolerance, in percent
+_TIME_IDLE = 20.0 # inter-frame timeout, in ms
+_TIME_LC = 13.5 # leader code, in ms
+_TIME_RC = 11.25 # repeat code, in ms
+_TIME_ONE = 2.25 # one data bit, in ms
+_TIME_ZERO = 1.125 # zero data bit, in ms
+_TIME_STOP = 0.562 # stop bit, in ms
+
class SamplerateError(Exception):
pass
)
options = (
{'id': 'polarity', 'desc': 'Polarity', 'default': 'active-low',
- 'values': ('active-low', 'active-high')},
+ 'values': ('auto', 'active-low', 'active-high')},
{'id': 'cd_freq', 'desc': 'Carrier Frequency', 'default': 0},
{'id': 'extended', 'desc': 'Extended NEC Protocol',
'default': 'no', 'values': ('yes', 'no')},
self.samplerate = value
def calc_rate(self):
- self.tolerance = 0.05 # +/-5%
- self.lc = int(self.samplerate * 0.0135) - 1 # 13.5ms
- self.rc = int(self.samplerate * 0.01125) - 1 # 11.25ms
- self.dazero = int(self.samplerate * 0.001125) - 1 # 1.125ms
- self.daone = int(self.samplerate * 0.00225) - 1 # 2.25ms
- self.stop = int(self.samplerate * 0.000652) - 1 # 0.652ms
- self.idle_to = int(self.samplerate * 0.020) - 1 # 20ms, arbitrary choice
+ self.tolerance = _TIME_TOL / 100
+ self.lc = int(self.samplerate * _TIME_LC / 1000) - 1
+ self.rc = int(self.samplerate * _TIME_RC / 1000) - 1
+ self.dazero = int(self.samplerate * _TIME_ZERO / 1000) - 1
+ self.daone = int(self.samplerate * _TIME_ONE / 1000) - 1
+ self.stop = int(self.samplerate * _TIME_STOP / 1000) - 1
+ self.idle_to = int(self.samplerate * _TIME_IDLE / 1000) - 1
def compare_with_tolerance(self, measured, base):
return (measured >= base * (1 - self.tolerance)
cd_count = int(self.samplerate / self.options['cd_freq']) + 1
prev_ir = None
- active = 0 if self.options['polarity'] == 'active-low' else 1
+ if self.options['polarity'] == 'auto':
+ # Take sample 0 as reference.
+ curr_level, = self.wait({'skip': 0})
+ active = 1 - curr_level
+ else:
+ active = 0 if self.options['polarity'] == 'active-low' else 1
self.is_extended = self.options['extended'] == 'yes'
want_addr_len = 16 if self.is_extended else 8