X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decoders%2Fpwm%2Fpd.py;h=d8626ee00824d427a53672e76b298e84f9233191;hp=0b7be458d881302e368bd778af0e5c4b2252ad8a;hb=6cbba91f23b9f9ace75b4722c9c0776b9211008d;hpb=bcf6548ba8b604fa56a9cf4f7f985e9f67dd5bb6

diff --git a/decoders/pwm/pd.py b/decoders/pwm/pd.py
index 0b7be45..d8626ee 100644
--- a/decoders/pwm/pd.py
+++ b/decoders/pwm/pd.py
@@ -20,6 +20,9 @@
 
 import sigrokdecode as srd
 
+class SamplerateError(Exception):
+    pass
+
 class Decoder(srd.Decoder):
     api_version = 3
     id = 'pwm'
@@ -28,7 +31,8 @@ class Decoder(srd.Decoder):
     desc = 'Analog level encoded in duty cycle percentage.'
     license = 'gplv2+'
     inputs = ['logic']
-    outputs = ['pwm']
+    outputs = []
+    tags = ['Encoding']
     channels = (
         {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
     )
@@ -49,19 +53,17 @@ class Decoder(srd.Decoder):
     )
 
     def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.samplerate = None
         self.ss_block = self.es_block = None
-        self.first_samplenum = None
-        self.start_samplenum = None
-        self.end_samplenum = None
-        self.num_cycles = 0
-        self.average = 0
 
     def metadata(self, key, value):
         if key == srd.SRD_CONF_SAMPLERATE:
             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 = \
@@ -89,51 +91,51 @@ class Decoder(srd.Decoder):
         self.put(self.ss_block, self.es_block, self.out_ann, [1, [period_s]])
 
     def putb(self, data):
-        self.put(self.num_cycles, self.num_cycles, self.out_binary, data)
+        self.put(self.ss_block, self.es_block, self.out_binary, data)
 
     def decode(self):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
 
-        # Get the first rising edge.
-        pin, = self.wait({0: 'e'})
-        if pin != self.startedge:
-            pin, = self.wait({0: 'e'})
+        num_cycles = 0
+        average = 0
+
+        # 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:
-                # Rising edge
-                # We are on a full cycle we can 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]])
-
-                # Report the duty cycle in the binary output.
-                self.putb([0, bytes([int(ratio * 256)])])
-
-                # Report the period in units of time.
-                period_t = float(period / self.samplerate)
-                self.putp(period_t)
-
-                # Update and report the new duty cycle average.
-                self.num_cycles += 1
-                self.average += percent
-                self.put(self.first_samplenum, self.es_block, self.out_average,
-                         float(self.average / self.num_cycles))
-            else:
-                # Falling edge
-                self.end_samplenum = self.ss_block = self.samplenum
+
+            # Get the next two edges. Setup some variables that get
+            # referenced in the calculation and in put() routines.
+            start_samplenum = self.samplenum
+            self.wait({0: 'e'})
+            end_samplenum = self.samplenum
+            self.wait({0: 'e'})
+            self.ss_block = start_samplenum
+            self.es_block = self.samplenum
+
+            # Calculate the period, the duty cycle, and its ratio.
+            period = self.samplenum - start_samplenum
+            duty = end_samplenum - start_samplenum
+            ratio = float(duty / period)
+
+            # Report the duty cycle in percent.
+            percent = float(ratio * 100)
+            self.putx([0, ['%f%%' % percent]])
+
+            # Report the duty cycle in the binary output.
+            self.putb([0, bytes([int(ratio * 256)])])
+
+            # Report the period in units of time.
+            period_t = float(period / self.samplerate)
+            self.putp(period_t)
+
+            # Update and report the new duty cycle average.
+            num_cycles += 1
+            average += percent
+            self.put(self.first_samplenum, self.es_block, self.out_average,
+                     float(average / num_cycles))