"""Pure timing checker used by the DSView decoder and unit tests. All time values in profiles are nanoseconds. The ACK delay in the vendor data sheets is a typical value only, so the delay window is intentionally an engineering warning threshold. ACK pulse width has specified limits and is therefore checked as PASS/FAIL. """ from collections import deque PROFILES = { '1SP0635': { 'ack_delay_typ_ns': 250.0, 'ack_width_min_ns': 400.0, 'ack_width_typ_ns': 700.0, 'ack_width_max_ns': 1050.0, 'fault_threshold_ns': 1500.0, }, '1SD536F2': { 'ack_delay_typ_ns': 380.0, 'ack_width_min_ns': 600.0, 'ack_width_typ_ns': 900.0, 'ack_width_max_ns': 1800.0, # The application manual calls >1.5 us a fault, while individual # data sheets allow ACK pulses up to 1.8 us. A correlated pulse in # the specified ACK range wins; otherwise the longer limit is used. 'fault_threshold_ns': 1800.0, }, } def format_ns(value_ns): if value_ns >= 1000000.0: return '%.3f ms' % (value_ns / 1000000.0) if value_ns >= 1000.0: return '%.3f us' % (value_ns / 1000.0) return '%.1f ns' % value_ns class TimingChecker(object): """Match Vin edges to Vstat pulses and return annotation dictionaries.""" def __init__(self, samplerate, profile='1SP0635', delay_tolerance_ns=100.0, vin_active_high=True, vstat_active_high=True, custom=None): if not samplerate: raise ValueError('samplerate is required') if profile == 'custom': if not custom: raise ValueError('custom profile values are required') self.spec = dict(custom) else: self.spec = dict(PROFILES[profile]) self.profile = profile self.samplerate = float(samplerate) self.delay_tolerance_ns = float(delay_tolerance_ns) self.vin_active_high = bool(vin_active_high) self.vstat_active_high = bool(vstat_active_high) self.pending = deque() self.status_start = None self.status_control = None # Long enough to avoid calling a merely late ACK "missing", while # still producing a useful annotation during a capture. self.ack_timeout_ns = max( self.spec['ack_delay_typ_ns'] + 3.0 * self.delay_tolerance_ns, self.spec['ack_delay_typ_ns'] + self.spec['ack_width_max_ns']) def samples_to_ns(self, samples): return float(samples) * 1000000000.0 / self.samplerate def ns_to_samples(self, value_ns): return max(1, int(round(float(value_ns) * self.samplerate / 1000000000.0))) def next_deadline(self): if not self.pending: return None return self.pending[0]['sample'] + self.ns_to_samples(self.ack_timeout_ns) def on_control_edge(self, sample, level): state_on = bool(level) == self.vin_active_high item = { 'sample': int(sample), 'level': int(level), 'edge': 'ON' if state_on else 'OFF', } self.pending.append(item) return [{ 'kind': 'control', 'start': int(sample), 'end': int(sample), 'text': 'Vin %s' % item['edge'], 'short': item['edge'], }] def expire(self, sample): events = [] timeout_samples = self.ns_to_samples(self.ack_timeout_ns) while self.pending and int(sample) >= self.pending[0]['sample'] + timeout_samples: item = self.pending.popleft() end = item['sample'] + timeout_samples events.append({ 'kind': 'missing', 'start': item['sample'], 'end': end, 'text': 'FAIL: no Vstat ACK after Vin %s (timeout %s)' % (item['edge'], format_ns(self.ack_timeout_ns)), 'short': 'NO ACK', }) return events def on_status_edge(self, sample, level): sample = int(sample) is_active = bool(level) == self.vstat_active_high events = self.expire(sample) if is_active: # Ignore a second active edge caused by an inconsistent trace. if self.status_start is not None: return events self.status_start = sample self.status_control = self.pending.popleft() if self.pending else None if self.status_control is not None: delay_ns = self.samples_to_ns(sample - self.status_control['sample']) typ_ns = self.spec['ack_delay_typ_ns'] delta_ns = delay_ns - typ_ns in_window = abs(delta_ns) <= self.delay_tolerance_ns events.append({ 'kind': 'delay_ok' if in_window else 'delay_warn', 'start': self.status_control['sample'], 'end': sample, 'delay_ns': delay_ns, 'text': '%s: ACK delay %s (typ %s, delta %+0.1f ns)' % ('PASS' if in_window else 'WARN', format_ns(delay_ns), format_ns(typ_ns), delta_ns), 'short': '%s %s' % ('OK' if in_window else 'WARN', format_ns(delay_ns)), }) return events if self.status_start is None: events.append({ 'kind': 'orphan', 'start': sample, 'end': sample, 'text': 'Unexpected inactive Vstat edge', 'short': 'Vstat?', }) return events start = self.status_start control = self.status_control width_ns = self.samples_to_ns(sample - start) self.status_start = None self.status_control = None lo = self.spec['ack_width_min_ns'] hi = self.spec['ack_width_max_ns'] if control is not None and lo <= width_ns <= hi: events.append({ 'kind': 'width_ok', 'start': start, 'end': sample, 'width_ns': width_ns, 'text': 'PASS: ACK width %s (limit %s...%s)' % (format_ns(width_ns), format_ns(lo), format_ns(hi)), 'short': 'ACK %s' % format_ns(width_ns), }) elif width_ns > self.spec['fault_threshold_ns']: events.append({ 'kind': 'fault', 'start': start, 'end': sample, 'width_ns': width_ns, 'text': 'FAULT: Vstat active for %s' % format_ns(width_ns), 'short': 'FAULT %s' % format_ns(width_ns), }) elif control is None: events.append({ 'kind': 'orphan', 'start': start, 'end': sample, 'width_ns': width_ns, 'text': 'Unexpected Vstat pulse %s (no Vin edge)' % format_ns(width_ns), 'short': 'ORPHAN %s' % format_ns(width_ns), }) else: events.append({ 'kind': 'width_fail', 'start': start, 'end': sample, 'width_ns': width_ns, 'text': 'FAIL: ACK width %s outside %s...%s' % (format_ns(width_ns), format_ns(lo), format_ns(hi)), 'short': 'BAD ACK %s' % format_ns(width_ns), }) return events