## 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
+## along with this program; if not, see <http://www.gnu.org/licenses/>.
##
import sigrokdecode as srd
+class SamplerateError(Exception):
+ pass
+
class Decoder(srd.Decoder):
- api_version = 2
+ api_version = 3
id = 'pwm'
name = 'PWM'
longname = 'Pulse-width modulation'
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'},
)
('raw', 'RAW file'),
)
- def __init__(self, **kwargs):
- self.ss = self.es = None
- self.first_transition = True
- self.first_samplenum = None
- self.start_samplenum = None
- self.end_samplenum = None
- self.oldpin = None
- self.num_cycles = 0
- self.average = 0
+ def __init__(self):
+ self.reset()
+
+ def reset(self):
+ self.samplerate = None
+ self.ss_block = self.es_block = None
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_bin = self.register(srd.OUTPUT_BINARY)
+ self.out_binary = self.register(srd.OUTPUT_BINARY)
self.out_average = \
self.register(srd.OUTPUT_META,
meta=(float, 'Average', 'PWM base (cycle) frequency'))
def putx(self, data):
- self.put(self.ss, self.es, self.out_ann, data)
+ self.put(self.ss_block, self.es_block, self.out_ann, data)
def putp(self, period_t):
# Adjust granularity.
else:
period_s = '%.1f ms' % (period_t * 1e3)
- self.put(self.ss, self.es, self.out_ann, [1, [period_s]])
+ 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_bin, data)
-
- def decode(self, ss, es, data):
-
- for (self.samplenum, pins) in data:
- # Ignore identical samples early on (for performance reasons).
- if self.oldpin == pins[0]:
- continue
-
- # Initialize self.oldpins with the first sample value.
- if self.oldpin is None:
- self.oldpin = pins[0]
- continue
-
- if self.first_transition:
- # First rising edge
- if self.oldpin != self.startedge:
- self.first_samplenum = self.samplenum
- self.start_samplenum = self.samplenum
- self.first_transition = False
- else:
- if self.oldpin != 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 = self.start_samplenum
- # Store the new rising edge position and the ending
- # edge interval.
- self.start_samplenum = self.es = 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, self.out_average,
- float(self.average / self.num_cycles))
- else:
- # Falling edge
- self.end_samplenum = self.ss = self.samplenum
-
- self.oldpin = pins[0]
+ 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.')
+
+ 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
+
+ # Keep getting samples for the period's middle and terminal edges.
+ # At the same time that last sample starts the next period.
+ while True:
+
+ # 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))
projects / libsigrokdecode.git / blobdiff