scope.py

"""
scope
=====

Code for talking to the BitScope series of USB digital mixed-signal scopes.
Only supports the BS000501 at the moment, but that's only because it's never
been tested on any other model.
"""

# pylama:ignore=E0611,E1101,W0201,W1203,W0631,C0103,R0902,R0912,R0913,R0914,R0915,C0415,W0601,W0102

import argparse
import array
import asyncio
from collections import namedtuple
from configparser import ConfigParser
import logging
import math
from pathlib import Path
import sys
from urllib.parse import urlparse

import streams
from utils import DotDict
import vm


Log = logging.getLogger(__name__)
AnalogParametersPath = Path('~/.config/scopething/analog.conf').expanduser()


class UsageError(Exception):
    pass


class ConfigurationError(Exception):
    pass


class Scope(vm.VirtualMachine):

    class AnalogParams(namedtuple('AnalogParams', ['la', 'lb', 'lc', 'ha', 'hb', 'hc', 'scale', 'offset', 'safe_low', 'safe_high', 'ab_offset'])):
        def __repr__(self):
            return (f"la={self.la:.3f} lb={self.lb:.3e} lc={self.lc:.3e} ha={self.ha:.3f} hb={self.hb:.3e} hc={self.hc:.3e} "
                    f"scale={self.scale:.3f}V offset={self.offset:.3f}V safe_low={self.safe_low:.2f}V safe_high={self.safe_high:.2f}V "
                    f"ab_offset={self.ab_offset*1000:.1f}mV")

    async def connect(self, url=None):
        if url is None:
            for device in streams.SerialStream.devices_matching(vid=0x0403, pid=0x6001):
                url = f'file:{device}'
                break
            else:
                raise RuntimeError("No matching serial device found")
        self.close()
        Log.info(f"Connecting to scope at {url}")
        parts = urlparse(url, scheme='file')
        if parts.scheme == 'file':
            self._reader = self._writer = streams.SerialStream(device=parts.path)
        elif parts.scheme == 'socket':
            host, port = parts.netloc.split(':', 1)
            self._reader, self._writer = await asyncio.open_connection(host, int(port))
        else:
            raise ValueError(f"Don't know what to do with url: {url}")
        self.url = url
        await self.reset()
        return self

    async def reset(self):
        Log.info("Resetting scope")
        await self.issue_reset()
        await self.issue_get_revision()
        revision = ((await self.read_replies(2))[1]).decode('ascii')
        if revision == 'BS000501':
            self.primary_clock_rate = 40000000
            self.primary_clock_period = 1/self.primary_clock_rate
            self.capture_buffer_size = 12 << 10
            self.awg_wavetable_size = 1024
            self.awg_sample_buffer_size = 1024
            self.awg_minimum_clock = 33
            self.logic_low = 0
            self.awg_maximum_voltage = self.clock_voltage = self.logic_high = 3.3
            self.analog_params = {'x1':  self.AnalogParams(1.1, -.05, 0, 1.1, -.05, -.05, 18.333, -7.517, -5.5, 8, 0)}
            self.analog_lo_min = 0.07
            self.analog_hi_max = 0.88
            self.timeout_clock_period = (1 << 8) * self.primary_clock_period
            self.timestamp_rollover = (1 << 32) * self.primary_clock_period
        else:
            raise RuntimeError(f"Unsupported scope, revision: {revision}")
        self._awg_running = False
        self._clock_running = False
        self.load_analog_params()
        Log.info(f"Initialised scope, revision: {revision}")

    def load_analog_params(self):
        config = ConfigParser()
        config.read(AnalogParametersPath)
        analog_params = {}
        for url in config.sections():
            if url == self.url:
                for probes in config[url]:
                    params = self.AnalogParams(*map(float, config[url][probes].split()))
                    analog_params[probes] = params
                    Log.debug(f"Loading saved parameters for {probes}: {params!r}")
        if analog_params:
            self.analog_params.update(analog_params)
            Log.info(f"Loaded analog parameters for probes: {', '.join(analog_params.keys())}")

    def save_analog_params(self):
        Log.info("Saving analog parameters")
        config = ConfigParser()
        config.read(AnalogParametersPath)
        config[self.url] = {probes: ' '.join(map(str, self.analog_params[probes])) for probes in self.analog_params}
        parent = AnalogParametersPath.parent
        if not parent.is_dir():
            parent.mkdir(parents=True)
        with open(AnalogParametersPath, 'w') as parameters_file:
            config.write(parameters_file)

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.close()

    def close(self):
        if super().close():
            Log.info("Closed scope")

    def calculate_lo_hi(self, low, high, params):
        if not isinstance(params, self.AnalogParams):
            params = self.AnalogParams(*list(params) + [None]*(11-len(params)))
        lo = (low - params.offset) / params.scale
        hi = (high - params.offset) / params.scale
        dl = params.la*lo + params.lb*hi + params.lc
        dh = params.ha*hi + params.hb*lo + params.hc
        return dl, dh

    async def capture(self, channels=['A'], trigger=None, trigger_level=None, trigger_type='rising', hair_trigger=False,
                      period=1e-3, nsamples=1000, timeout=None, low=None, high=None, raw=False, trigger_position=0.25, probes='x1'):
        analog_channels = set()
        logic_channels = set()
        for channel in channels:
            channel = channel.upper()
            if channel in {'A', 'B'}:
                analog_channels.add(channel)
                if trigger is None:
                    trigger = channel
            elif channel == 'L':
                logic_channels.update(range(8))
                if trigger is None:
                    trigger = {0: 1}
            elif channel in {'L0', 'L1', 'L2', 'L3', 'L4', 'L5', 'L6', 'L7'}:
                i = int(channel[1:])
                logic_channels.add(i)
                if trigger is None:
                    trigger = {i: 1}
            else:
                raise ValueError(f"Unrecognised channel: {channel}")
        if self._awg_running and 4 in logic_channels:
            logic_channels.remove(4)
        if self._clock_running and 5 in logic_channels:
            logic_channels.remove(5)
        if 'A' in analog_channels and 7 in logic_channels:
            logic_channels.remove(7)
        if 'B' in analog_channels and 6 in logic_channels:
            logic_channels.remove(6)
        analog_enable = sum(1 << (ord(channel)-ord('A')) for channel in analog_channels)
        logic_enable = sum(1 << channel for channel in logic_channels)

        for capture_mode in vm.CaptureModes:
            ticks = int(round(period / self.primary_clock_period / nsamples))
            clock_scale = 1
            if capture_mode.analog_channels == len(analog_channels) and capture_mode.logic_channels == bool(logic_channels):
                Log.debug(f"Considering trace mode {capture_mode.trace_mode.name}...")
                if ticks > capture_mode.clock_high and capture_mode.clock_divide > 1:
                    clock_scale = min(capture_mode.clock_divide, int(math.ceil(period / self.primary_clock_period / nsamples / capture_mode.clock_high)))
                    ticks = int(round(period / self.primary_clock_period / nsamples / clock_scale))
                    if ticks > capture_mode.clock_low:
                        if ticks > capture_mode.clock_high:
                            ticks = capture_mode.clock_high
                        Log.debug(f"- try with tick count {ticks} x {clock_scale}")
                    else:
                        continue
                elif ticks >= capture_mode.clock_low:
                    if ticks > capture_mode.clock_high:
                        ticks = capture_mode.clock_high
                    Log.debug(f"- try with tick count {ticks}")
                else:
                    Log.debug("- mode too slow")
                    continue
                actual_nsamples = int(round(period / self.primary_clock_period / ticks / clock_scale))
                if len(analog_channels) == 2:
                    actual_nsamples -= actual_nsamples % 2
                buffer_width = self.capture_buffer_size // capture_mode.sample_width
                if logic_channels and analog_channels:
                    buffer_width //= 2
                if actual_nsamples <= buffer_width:
                    Log.debug(f"- OK; period is {actual_nsamples} samples")
                    nsamples = actual_nsamples
                    break
                Log.debug(f"- insufficient buffer space for necessary {actual_nsamples} samples")
        else:
            raise ConfigurationError("Unable to find appropriate capture mode")
        sample_period = ticks*clock_scale*self.primary_clock_period
        sample_rate = 1/sample_period
        if trigger_position and sample_rate > 5e6:
            Log.warning("Pre-trigger capture not supported above 5M samples/s; forcing trigger_position=0")
            trigger_position = 0

        if raw:
            analog_params = None
            lo, hi = low, high
        else:
            analog_params = self.analog_params[probes]
            if low is None:
                low = analog_params.safe_low if analog_channels else self.logic_low
            elif low < analog_params.safe_low:
                Log.warning(f"Voltage range is below safe minimum: {low} < {analog_params.safe_low}")
            if high is None:
                high = analog_params.safe_high if analog_channels else self.logic_high
            elif high > analog_params.safe_high:
                Log.warning(f"Voltage range is above safe maximum: {high} > {analog_params.safe_high}")
            lo, hi = self.calculate_lo_hi(low, high, analog_params)

        spock_option = vm.SpockOption.TriggerTypeHardwareComparator
        kitchen_sink_a = kitchen_sink_b = 0
        if self._awg_running:
            kitchen_sink_b |= vm.KitchenSinkB.WaveformGeneratorEnable
        if trigger == 'A' or 7 in logic_channels:
            kitchen_sink_a |= vm.KitchenSinkA.ChannelAComparatorEnable
        if trigger == 'B' or 6 in logic_channels:
            kitchen_sink_a |= vm.KitchenSinkA.ChannelBComparatorEnable
        if analog_channels:
            kitchen_sink_b |= vm.KitchenSinkB.AnalogFilterEnable
        if trigger_level is None:
            trigger_level = (high + low) / 2
        analog_trigger_level = (trigger_level - analog_params.offset) / analog_params.scale if not raw else trigger_level
        if isinstance(trigger, dict):
            trigger_logic = 0
            trigger_mask = 0xff
            for channel, value in trigger.items():
                if isinstance(channel, str):
                    if channel.startswith('L'):
                        channel = int(channel[1:])  # noqa
                    else:
                        raise ValueError("Unrecognised trigger value")
                if channel < 0 or channel > 7:
                    raise ValueError("Unrecognised trigger value")
                mask = 1 << channel
                trigger_mask &= ~mask
                if value:
                    trigger_logic |= mask
        elif trigger in {'A', 'B'}:
            if trigger == 'A':
                spock_option |= vm.SpockOption.TriggerSourceA
                trigger_logic = 0x80
            elif trigger == 'B':
                spock_option |= vm.SpockOption.TriggerSourceB
                trigger_logic = 0x40
            trigger_mask = 0xff ^ trigger_logic
        else:
            raise ValueError("Unrecognised trigger value")
        trigger_type = trigger_type.lower()
        if trigger_type in {'falling', 'below'}:
            spock_option |= vm.SpockOption.TriggerInvert
        elif trigger_type not in {'rising', 'above'}:
            raise ValueError("Unrecognised trigger_type")
        trigger_outro = 4 if hair_trigger else 8
        trigger_intro = 0 if trigger_type in {'above', 'below'} else trigger_outro
        trigger_samples = min(max(0, int(nsamples*trigger_position)), nsamples)
        trace_outro = max(0, nsamples-trigger_samples-trigger_outro)
        trace_intro = max(0, trigger_samples-trigger_intro)
        if timeout is None:
            trigger_timeout = 0
        else:
            trigger_timeout = int(math.ceil(((trigger_intro+trigger_outro+trace_outro+2)*ticks*clock_scale*self.primary_clock_period
                                             + timeout)/self.timeout_clock_period))
            if trigger_timeout > vm.Registers.Timeout.maximum_value:
                if timeout > 0:
                    raise ConfigurationError("Required trigger timeout too long")
                raise ConfigurationError("Required trigger timeout too long, use a later trigger position")

        Log.info(f"Begin {('mixed' if logic_channels else 'analogue') if analog_channels else 'logic'} signal capture "
                 f"at {sample_rate:,.0f} samples per second (trace mode {capture_mode.trace_mode.name})")
        async with self.transaction():
            await self.set_registers(TraceMode=capture_mode.trace_mode, BufferMode=capture_mode.buffer_mode,
                                     SampleAddress=0, ClockTicks=ticks, ClockScale=clock_scale,
                                     TriggerLevel=analog_trigger_level, TriggerLogic=trigger_logic, TriggerMask=trigger_mask,
                                     TraceIntro=trace_intro, TraceOutro=trace_outro, TraceDelay=0, Timeout=trigger_timeout,
                                     TriggerIntro=trigger_intro//2, TriggerOutro=trigger_outro//2, Prelude=0,
                                     SpockOption=spock_option, ConverterLo=lo, ConverterHi=hi,
                                     KitchenSinkA=kitchen_sink_a, KitchenSinkB=kitchen_sink_b,
                                     AnalogEnable=analog_enable, DigitalEnable=logic_enable)
            await self.issue_program_spock_registers()
            await self.issue_configure_device_hardware()
            await self.issue_triggered_trace()
        while True:
            try:
                code, timestamp = (int(x, 16) for x in await self.read_replies(2))
                if code != vm.TraceStatus.Wait:
                    break
            except asyncio.CancelledError:
                await self.issue_cancel_trace()
        cause = {vm.TraceStatus.Done: 'trigger', vm.TraceStatus.Auto: 'timeout', vm.TraceStatus.Stop: 'cancel'}[code]
        start_timestamp = timestamp - nsamples*ticks*clock_scale
        if start_timestamp < 0:
            start_timestamp += 1 << 32
            timestamp += 1 << 32
        address = int((await self.read_replies(1))[0], 16)
        if capture_mode.analog_channels == 2:
            address -= address % 2

        traces = DotDict()

        timestamps = array.array('d', (i * sample_period for i in range(nsamples)))
        for dump_channel, channel in enumerate(sorted(analog_channels)):
            asamples = nsamples // len(analog_channels)
            async with self.transaction():
                await self.set_registers(SampleAddress=(address - nsamples) % buffer_width,
                                         DumpMode=vm.DumpMode.Native if capture_mode.sample_width == 2 else vm.DumpMode.Raw,
                                         DumpChan=dump_channel, DumpCount=asamples, DumpRepeat=1, DumpSend=1, DumpSkip=0)
                await self.issue_program_spock_registers()
                await self.issue_analog_dump_binary()
            value_multiplier, value_offset = (1, 0) if raw else (high-low, low-analog_params.ab_offset/2*(1 if channel == 'A' else -1))
            data = await self.read_analog_samples(asamples, capture_mode.sample_width)
            series = DotDict({'channel': channel,
                              'capture_start': start_timestamp * self.primary_clock_period,
                              'timestamps': timestamps[dump_channel::len(analog_channels)] if len(analog_channels) > 1 else timestamps,
                              'samples': array.array('f', (value*value_multiplier+value_offset for value in data)),
                              'sample_period': sample_period*len(analog_channels),
                              'sample_rate': sample_rate/len(analog_channels),
                              'cause': cause})
            if cause == 'trigger' and channel == trigger:
                series.trigger_timestamp = series.timestamps[trigger_samples // len(analog_channels)]
                series.trigger_level = trigger_level
                series.trigger_type = trigger_type
            traces[channel] = series
        if logic_channels:
            async with self.transaction():
                await self.set_registers(SampleAddress=(address - nsamples) % buffer_width,
                                         DumpMode=vm.DumpMode.Raw, DumpChan=128, DumpCount=nsamples, DumpRepeat=1, DumpSend=1, DumpSkip=0)
                await self.issue_program_spock_registers()
                await self.issue_analog_dump_binary()
            data = await self.read_logic_samples(nsamples)
            for i in logic_channels:
                mask = 1 << i
                channel = f'L{i}'
                series = DotDict({'channel': channel,
                                  'capture_start': start_timestamp * self.primary_clock_period,
                                  'timestamps': timestamps,
                                  'samples': array.array('B', (1 if value & mask else 0 for value in data)),
                                  'sample_period': sample_period,
                                  'sample_rate': sample_rate,
                                  'cause': cause})
                if cause == 'trigger' and isinstance(trigger, dict) and i in trigger:
                    series.trigger_timestamp = series.timestamps[trigger_samples]
                    series.trigger_level = trigger[i]
                    series.trigger_type = trigger_type
                traces[channel] = series
        Log.info(f"{nsamples} samples captured on {cause}, traces: {', '.join(traces)}")
        return traces

    async def start_waveform(self, frequency, waveform='sine', ratio=0.5, low=0, high=None, min_samples=50, max_error=1e-4):
        if self._clock_running:
            raise UsageError("Cannot start waveform generator while clock in use")
        if high is None:
            high = self.awg_maximum_voltage
        elif high < 0 or high > self.awg_maximum_voltage:
            raise ValueError(f"high out of range (0-{self.awg_maximum_voltage})")
        if low < 0 or low > high:
            raise ValueError("low out of range (0-high)")
        max_clock = min(vm.Registers.Clock.maximum_value, int(math.floor(self.primary_clock_rate / frequency / min_samples)))
        min_clock = max(self.awg_minimum_clock, int(math.ceil(self.primary_clock_rate / frequency / self.awg_sample_buffer_size)))
        best_solution = None
        for clock in range(min_clock, max_clock+1):
            width = self.primary_clock_rate / frequency / clock
            nwaves = int(self.awg_sample_buffer_size / width)
            size = int(round(nwaves * width))
            actualf = self.primary_clock_rate * nwaves / size / clock
            if actualf == frequency:
                Log.debug(f"Exact solution: size={size} nwaves={nwaves} clock={clock}")
                break
            error = abs(frequency - actualf) / frequency
            if error < max_error and (best_solution is None or error < best_solution[0]):  # noqa
                best_solution = error, size, nwaves, clock, actualf
        else:
            if best_solution is None:
                raise ConfigurationError("No solution to required frequency/min_samples/max_error")
            error, size, nwaves, clock, actualf = best_solution
            Log.debug(f"Best solution: size={size} nwaves={nwaves} clock={clock} actualf={actualf}")
        async with self.transaction():
            if isinstance(waveform, str):
                mode = {'sine': 0, 'triangle': 1, 'exponential': 2, 'square': 3}[waveform.lower()]
                await self.set_registers(Cmd=0, Mode=mode, Ratio=ratio)
                await self.issue_synthesize_wavetable()
            elif len(waveform) == self.awg_wavetable_size:
                waveform = bytes(min(max(0, int(round(y*256))), 255) for y in waveform)
                await self.set_registers(Cmd=0, Mode=1, Address=0, Size=1)
                await self.wavetable_write_bytes(waveform)
            else:
                raise ValueError(f"waveform must be a valid name or a sequence of {self.awg_wavetable_size} samples [0,1)")
        async with self.transaction():
            offset = (high+low)/2 - self.awg_maximum_voltage/2
            await self.set_registers(Cmd=0, Mode=0, Level=(high-low)/self.awg_maximum_voltage,
                                     Offset=offset/self.awg_maximum_voltage,
                                     Ratio=nwaves*self.awg_wavetable_size/size,
                                     Index=0, Address=0, Size=size)
            await self.issue_translate_wavetable()
        async with self.transaction():
            await self.set_registers(Cmd=2, Mode=0, Clock=clock, Modulo=size,
                                     Mark=10, Space=1, Rest=0x7f00, Option=0x8004)
            await self.issue_control_clock_generator()
        async with self.transaction():
            await self.set_registers(KitchenSinkB=vm.KitchenSinkB.WaveformGeneratorEnable)
            await self.issue_configure_device_hardware()
        self._awg_running = True
        Log.info(f"Signal generator running at {actualf:0.1f}Hz")
        return actualf

    async def stop_waveform(self):
        if not self._awg_running:
            raise UsageError("Waveform generator not in use")
        async with self.transaction():
            await self.set_registers(Cmd=1, Mode=0)
            await self.issue_control_clock_generator()
            await self.set_registers(KitchenSinkB=0)
            await self.issue_configure_device_hardware()
        Log.info("Signal generator stopped")
        self._awg_running = False

    async def start_clock(self, frequency, ratio=0.5, max_error=1e-4):
        if self._awg_running:
            raise UsageError("Cannot start clock while waveform generator in use")
        ticks = min(max(2, int(round(self.primary_clock_rate / frequency))), vm.Registers.Clock.maximum_value)
        fall = min(max(1, int(round(ticks * ratio))), ticks-1)
        actualf, actualr = self.primary_clock_rate / ticks, fall / ticks
        if abs(actualf - frequency) / frequency > max_error:
            raise ConfigurationError("No solution to required frequency and max_error")
        async with self.transaction():
            await self.set_registers(Map5=0x12, Clock=ticks, Rise=0, Fall=fall, Control=0x80, Cmd=3, Mode=0)
            await self.issue_control_clock_generator()
        self._clock_running = True
        Log.info(f"Clock generator running at {actualf:0.1f}Hz, {actualr*100:.0f}% duty cycle")
        return actualf, actualr

    async def stop_clock(self):
        if not self._clock_running:
            raise UsageError("Clock not in use")
        async with self.transaction():
            await self.set_registers(Map5=0, Cmd=1, Mode=0)
            await self.issue_control_clock_generator()
        Log.info("Clock generator stopped")
        self._clock_running = False

    async def calibrate(self, probes='x1', n=32, save=True):
        """
        Derive values for the analogue parameters based on generating a 3.3V 2kHz clock
        signal and then sampling the analogue channels to measure this. The first step is
        to set the low and high range DACs to 1/3 and 2/3, respectively. This results in
        *neutral* voltages matching the three series 300Ω resistances created by the ADC
        ladder resistance and the upper and lower bias resistors. Thus no current should
        be flowing in or out of the DACs and their effect on the ADC range voltages can
        be ignored. This allows an initial measurement to determine the full analogue
        range and zero offset.

        After this initial measurement, an `n`x`n` matrix of measurements are taken with
        different `lo` and `hi` DAC input values and these are used, with the known clock
        voltage, to reverse out the actual `low` and `high` measurement voltage range.
        The full set of measurements are then fed into the SciPy SLSQP minimiser to find
        parameters for two plane functions mapping the `low` and `high` voltages to the
        necessary `lo` and `hi` DAC values to achieve these. (Note that these functions
        are constrained to ensure that they pass through the *neutral* points.

        A further minimisation step is done to determine the safe analogue range based
        on the observed linear range of the DACs (`self.analog_lo_min` to
        `self.analog_hi_max`). The mean of the measured offsets between the A and B
        channel readings are used to determine an AB offset.
        """
        import numpy as np
        from scipy.optimize import minimize
        items = []

        async def measure(lo, hi, period=2e-3, chop=True):
            if chop:
                traces = await self.capture(channels=['A', 'B'], period=period, nsamples=2000, timeout=0, low=lo, high=hi, raw=True)
                A = np.array(traces.A.samples)
                B = np.array(traces.B.samples)
            else:
                A = np.array((await self.capture(channels=['A'], period=period/2, nsamples=1000, timeout=0, low=lo, high=hi, raw=True)).A.samples)
                B = np.array((await self.capture(channels=['B'], period=period/2, nsamples=1000, timeout=0, low=lo, high=hi, raw=True)).B.samples)
            Amean = A.mean()
            Azero, Afull = np.median(A[A <= Amean]), np.median(A[A >= Amean])
            Bmean = B.mean()
            Bzero, Bfull = np.median(B[B <= Bmean]), np.median(B[B >= Bmean])
            return (Azero + Bzero) / 2, (Afull + Bfull) / 2, ((Afull - Bfull) + (Azero - Azero)) / 2

        await self.start_clock(frequency=2000)
        zero, full, offset = await measure(1/3, 2/3)
        zero = (zero + 1) / 3
        full = (full + 1) / 3
        analog_scale = self.clock_voltage / (full - zero)
        analog_offset = -zero * analog_scale
        Log.info(f"Analog full range = {analog_scale:.2f}V, zero offset = {analog_offset:.2f}V")
        for lo in np.linspace(self.analog_lo_min, 0.5, n, endpoint=False):
            for hi in np.linspace(self.analog_hi_max, 0.5, n):
                zero, full, offset = await measure(lo, hi, 2e-3 if len(items) % 4 < 2 else 1e-3, len(items) % 2 == 0)
                if 0.01 < zero < full < 0.99:
                    analog_range = self.clock_voltage / (full - zero)
                    items.append((lo, hi, -zero*analog_range, (1-zero)*analog_range, offset*analog_range))
        await self.stop_clock()
        lo, hi, low, high, offset = np.array(items).T  # noqa

        def f(params):
            dl, dh = self.calculate_lo_hi(low, high, self.AnalogParams(*params, analog_scale, analog_offset, None, None, None))
            return np.sqrt((lo-dl)**2 + (hi-dh)**2).mean()

        start_params = self.analog_params.get(probes, [1, 0, 0, 1, 0, 0])[:6]
        result = minimize(f, start_params, method='SLSQP',
                          bounds=[(1, np.inf), (-np.inf, 0), (0, np.inf), (1, np.inf), (-np.inf, 0), (-np.inf, 0)],
                          constraints=[{'type': 'eq', 'fun': lambda x: x[0]*1/3 + x[1]*2/3 + x[2] - 1/3},
                                       {'type': 'eq', 'fun': lambda x: x[3]*2/3 + x[4]*1/3 + x[5] - 2/3}])
        if result.success:
            Log.info(f"Calibration succeeded: {result.message}")
            params = self.AnalogParams(*result.x, analog_scale, analog_offset, None, None, None)

            def f(x):  # noqa
                lo, hi = self.calculate_lo_hi(x[0], x[1], params)
                return np.sqrt((self.analog_lo_min - lo)**2 + (self.analog_hi_max - hi)**2)

            safe_low, safe_high = minimize(f, (low[0], high[0])).x
            offset_mean = offset.mean()
            params = self.analog_params[probes] = self.AnalogParams(*result.x, analog_scale, analog_offset, safe_low, safe_high, offset_mean)
            Log.info(f"{params!r} ±{100*offset.std()/offset_mean:.1f}%)")
            clo, chi = self.calculate_lo_hi(low, high, params)
            lo_error = np.sqrt((((clo-lo)/(hi-lo))**2).mean())
            hi_error = np.sqrt((((chi-hi)/(hi-lo))**2).mean())
            Log.info(f"Mean error: lo={lo_error*10000:.1f}bps hi={hi_error*10000:.1f}bps")
            if save:
                self.save_analog_params()
        else:
            Log.warning(f"Calibration failed: {result.message}")
        return result.success

    def __repr__(self):
        return f"<Scope {self.url}>"


# $ ipython3 --pylab
# Using matplotlib backend: MacOSX
#
# In [1]: run scope
#
# In [2]: start_waveform(2000, 'triangle')
# Out[2]: 2000.0
#
# In [3]: traces = capture(['A','B'], period=1e-3, low=0, high=3.3)
#
# In [4]: plot(traces.A.timestamps, traces.A.samples)
# Out[4]: [<matplotlib.lines.Line2D at 0x10c782160>]
#
# In [5]: plot(traces.B.timestamps, traces.B.samples)
# Out[5]: [<matplotlib.lines.Line2D at 0x10e6ea320>]


async def main():
    global s
    parser = argparse.ArgumentParser(description="scopething")
    parser.add_argument('url', nargs='?', default=None, type=str, help="Device to connect to")
    parser.add_argument('--debug', action='store_true', default=False, help="Debug logging")
    parser.add_argument('--verbose', action='store_true', default=False, help="Verbose logging")
    args = parser.parse_args()
    logging.basicConfig(level=logging.DEBUG if args.debug else (logging.INFO if args.verbose else logging.WARNING), stream=sys.stdout)
    s = await Scope().connect(args.url)


def await_(g):
    task = asyncio.Task(g)
    while True:
        try:
            return asyncio.get_event_loop().run_until_complete(task)
        except KeyboardInterrupt:
            task.cancel()


def capture(*args, **kwargs):
    return await_(s.capture(*args, **kwargs))


def capturep(*args, **kwargs):
    import pandas
    traces = capture(*args, **kwargs)
    return pandas.DataFrame({channel: pandas.Series(trace.samples, trace.timestamps) for (channel, trace) in traces.items()})


def calibrate(*args, **kwargs):
    return await_(s.calibrate(*args, **kwargs))


def start_waveform(*args, **kwargs):
    return await_(s.start_waveform(*args, **kwargs))


def start_clock(*args, **kwargs):
    return await_(s.start_clock(*args, **kwargs))


if __name__ == '__main__':
    asyncio.get_event_loop().run_until_complete(main())