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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2014 Torsten Duwe <duwe@suse.de>
## Copyright (C) 2014 Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
##
## 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, see <http://www.gnu.org/licenses/>.
##
import sigrokdecode as srd
class Decoder(srd.Decoder):
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']
channels = (
{'id': 'data', 'name': 'Data', 'desc': 'Data line'},
)
options = (
{'id': 'polarity', 'desc': 'Polarity', 'default': 'active-high',
'values': ('active-low', 'active-high')},
)
annotations = (
('duty-cycle', 'Duty cycle'),
('period', 'Period'),
)
annotation_rows = (
('duty-cycle', 'Duty cycle', (0,)),
('period', 'Period', (1,)),
)
binary = (
('raw', 'RAW file'),
)
def __init__(self):
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 = \
self.register(srd.OUTPUT_META,
meta=(float, 'Average', 'PWM base (cycle) frequency'))
def putx(self, data):
self.put(self.ss_block, self.es_block, self.out_ann, data)
def putp(self, period_t):
# Adjust granularity.
if period_t == 0 or period_t >= 1:
period_s = '%.1f s' % (period_t)
elif period_t <= 1e-12:
period_s = '%.1f fs' % (period_t * 1e15)
elif period_t <= 1e-9:
period_s = '%.1f ps' % (period_t * 1e12)
elif period_t <= 1e-6:
period_s = '%.1f ns' % (period_t * 1e9)
elif period_t <= 1e-3:
period_s = '%.1f μs' % (period_t * 1e6)
else:
period_s = '%.1f ms' % (period_t * 1e3)
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)
def decode(self):
# Get the first rising edge.
pin, = self.wait({0: 'e'})
if pin != self.startedge:
pin, = self.wait({0: 'e'})
self.first_samplenum = self.samplenum
self.start_samplenum = self.samplenum
# Handle all next edges.
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
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