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-rw-r--r--decoders/pwm/pd.py33
1 files changed, 14 insertions, 19 deletions
diff --git a/decoders/pwm/pd.py b/decoders/pwm/pd.py
index 5d0b4a5..a2fbb0f 100644
--- a/decoders/pwm/pd.py
+++ b/decoders/pwm/pd.py
@@ -61,7 +61,6 @@ class Decoder(srd.Decoder):
self.samplerate = value
def start(self):
- self.startedge = 0 if self.options['polarity'] == 'active-low' else 1
self.out_ann = self.register(srd.OUTPUT_ANN)
self.out_binary = self.register(srd.OUTPUT_BINARY)
self.out_average = \
@@ -93,33 +92,29 @@ class Decoder(srd.Decoder):
def decode(self):
- # Wait for an "active" edge (depends on config).
- self.wait({0: 'f' if self.startedge == 0 else 'r'})
+ # Wait for an "active" edge (depends on config). This starts
+ # the first full period of the inspected signal waveform.
+ self.wait({0: 'f' if self.options['polarity'] == 'active-low' else 'r'})
self.first_samplenum = self.samplenum
- self.start_samplenum = self.samplenum
- # Handle all next edges.
+ # Keep getting samples for the period's middle and terminal edges.
+ # At the same time that last sample starts the next period.
while True:
- pin, = self.wait({0: 'e'})
- if pin != self.startedge:
- # Non-active edge
- self.end_samplenum = self.ss_block = self.samplenum
- continue
+ # Get the next two edges. Setup some variables that get
+ # referenced in the calculation and in put() routines.
+ self.start_samplenum = self.samplenum
+ pins = self.wait({0: 'e'})
+ self.end_samplenum = self.samplenum
+ pins = self.wait({0: 'e'})
+ self.ss_block = self.start_samplenum
+ self.es_block = self.samplenum
- # Active edge
- # We are on a full cycle we can calculate
- # the period, the duty cycle and its ratio.
+ # Calculate the period, the duty cycle, and its ratio.
period = self.samplenum - self.start_samplenum
duty = self.end_samplenum - self.start_samplenum
ratio = float(duty / period)
- # This interval starts at this edge.
- self.ss_block = self.start_samplenum
- # Store the new rising edge position and the ending
- # edge interval.
- self.start_samplenum = self.es_block = self.samplenum
-
# Report the duty cycle in percent.
percent = float(ratio * 100)
self.putx([0, ['%f%%' % percent]])