From 2f6d3f79ffa664d329af2cf9a9d3f379af733d7b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Robert=20J=C3=B6rdens?= Date: Fri, 2 Nov 2018 14:55:56 +0000 Subject: [PATCH] ad9910: add phase modes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * simplified and cross-referenced the explanation of the different phase modes. * semantically and functionally merged absolute and tracking/coherent phase modes. * simplified numerics to calculate phase correction * added warning about possible inconsistency with DMA and default phase mode * restricted __all__ imports * moved continuous/relative phase offset tracking from an instance variable to a "handle" returned by set()/set_mu() in order to avoid state inconsistency with DMA (#1113 #1115) for #1143 Signed-off-by: Robert Jördens --- artiq/coredevice/ad9910.py | 125 +++++++++++++++++++++++++++++++++---- 1 file changed, 113 insertions(+), 12 deletions(-) diff --git a/artiq/coredevice/ad9910.py b/artiq/coredevice/ad9910.py index 321d0ee1e..f26ce010b 100644 --- a/artiq/coredevice/ad9910.py +++ b/artiq/coredevice/ad9910.py @@ -1,14 +1,27 @@ from numpy import int32, int64 -from artiq.language.core import kernel, delay, portable +from artiq.language.core import ( + kernel, delay, portable, delay_mu, now_mu, at_mu) from artiq.language.units import us, ns, ms from artiq.coredevice import spi2 as spi from artiq.coredevice import urukul +# Work around ARTIQ-Python import machinery urukul_sta_pll_lock = urukul.urukul_sta_pll_lock urukul_sta_smp_err = urukul.urukul_sta_smp_err +__all__ = [ + "AD9910", + "PHASE_MODE_CONTINUOUS", "PHASE_MODE_ABSOLUTE", "PHASE_MODE_TRACKING" +] + + +_PHASE_MODE_DEFAULT = -1 +PHASE_MODE_CONTINUOUS = 0 +PHASE_MODE_ABSOLUTE = 1 +PHASE_MODE_TRACKING = 2 + _AD9910_REG_CFR1 = 0x00 _AD9910_REG_CFR2 = 0x01 _AD9910_REG_CFR3 = 0x02 @@ -59,7 +72,7 @@ class AD9910: set this to the delay tap number returned. """ kernel_invariants = {"chip_select", "cpld", "core", "bus", - "ftw_per_hz", "pll_n", "io_update_delay"} + "ftw_per_hz", "pll_n", "io_update_delay", "sysclk_per_mu"} def __init__(self, dmgr, chip_select, cpld_device, sw_device=None, pll_n=40, pll_cp=7, pll_vco=5, sync_delay_seed=-1, @@ -77,7 +90,9 @@ class AD9910: assert self.cpld.refclk/4 <= 60e6 sysclk = self.cpld.refclk*pll_n/4 # Urukul clock fanout divider assert sysclk <= 1e9 - self.ftw_per_hz = 1./sysclk*(int64(1) << 32) + self.ftw_per_hz = (1 << 32)/sysclk + self.sysclk_per_mu = int(round(sysclk*self.core.ref_period)) + assert self.sysclk_per_mu == sysclk*self.core.ref_period assert 0 <= pll_vco <= 5 vco_min, vco_max = [(370, 510), (420, 590), (500, 700), (600, 880), (700, 950), (820, 1150)][pll_vco] @@ -87,6 +102,49 @@ class AD9910: self.pll_cp = pll_cp self.sync_delay_seed = sync_delay_seed self.io_update_delay = io_update_delay + self.phase_mode = PHASE_MODE_CONTINUOUS + + @kernel + def set_phase_mode(self, phase_mode): + """Sets the default phase mode for future calls to :meth:`set` and + :meth:`set_mu`. Supported phase modes are: + + * :const:`PHASE_MODE_CONTINUOUS`: the phase accumulator is unchanged + when changing frequency or phase. The DDS phase is the sum of the + phase accumulator and the phase offset. The only discontinuous + changes in the DDS output phase come from changes to the phase + offset. This mode is also knows as "relative phase mode". + :math:`\phi(t) = q(t^\prime) + p + (t - t^\prime) f` + + * :const:`PHASE_MODE_ABSOLUTE`: the phase accumulator is reset when + changing frequency or phase. Thus, the phase of the DDS at the + time of the change is equal to the specified phase offset. + :math:`\phi(t) = p + (t - t^\prime) f` + + * :const:`PHASE_MODE_TRACKING`: when changing frequency or phase, + the phase accumulator is cleared and the phase offset is offset + by the value the phase accumulator would have if the DDS had been + running at the specified frequency since a given fiducial + time stamp. This is functionally equivalent to + :const:`PHASE_MODE_ABSOLUTE`. The only difference is the fiducial + time stamp. This mode is also known as "coherent phase mode". + :math:`\phi(t) = p + (t - T) f` + + Where: + + * :math:`\phi(t)`: the DDS output phase + * :math:`q(t) = \phi(t) - p`: DDS internal phase accumulator + * :math:`p`: phase offset + * :math:`f`: frequency + * :math:`t^\prime`: time stamp of setting :math:`p`, :math:`f` + * :math:`T`: fiducial time stamp + * :math:`t`: running time + + .. warning:: This setting may become inconsistent when used as part of + a DMA recording. When using DMA, it is recommended to specify the + phase mode explicitly when calling :meth:`set` or :meth:`set_mu`. + """ + self.phase_mode = phase_mode @kernel def write32(self, addr, data): @@ -190,20 +248,53 @@ class AD9910: self.cpld.io_update.pulse(1*us) @kernel - def set_mu(self, ftw, pow=0, asf=0x3fff): + def set_mu(self, ftw, pow=0, asf=0x3fff, phase_mode=_PHASE_MODE_DEFAULT, + ref_time=-1): """Set profile 0 data in machine units. + This uses machine units (FTW, POW, ASF). The frequency tuning word + width is 32, the phase offset word width is 16, and the amplitude + scale factor width is 12. + After the SPI transfer, the shared IO update pin is pulsed to activate the data. + .. seealso: :meth:`set_phase_mode` for a definition of the different + phase modes. + :param ftw: Frequency tuning word: 32 bit. :param pow: Phase tuning word: 16 bit unsigned. :param asf: Amplitude scale factor: 14 bit unsigned. + :param phase_mode: If specified, overrides the default phase mode set + by :meth:`set_phase_mode` for this call. + :param ref_time: Fiducial time used to compute absolute or tracking + phase updates. In machine units as obtained by `now_mu()`. + :return: Resulting phase offset word after application of phase + tracking offset. When using :const:`PHASE_MODE_CONTINUOUS` in + subsequent calls, use this value as the "current" phase. """ + if phase_mode == _PHASE_MODE_DEFAULT: + phase_mode = self.phase_mode + # Align to coarse RTIO which aligns SYNC_CLK + at_mu(now_mu() & ~0xf) + if phase_mode != PHASE_MODE_CONTINUOUS: + # Auto-clear phase accumulator on IO_UPDATE. + # This is active already for the next IO_UPDATE + self.write32(_AD9910_REG_CFR1, 0x00002002) + if ref_time >= 0: + # 32 LSB are sufficient. + # Also no need to use IO_UPDATE time as this + # is equivalent to an output pipeline latency. + dt = int32(now_mu()) - int32(ref_time) + pow += dt*ftw*self.sysclk_per_mu >> 16 self.write64(_AD9910_REG_PR0, (asf << 16) | pow, ftw) - # align IO_UPDATE to SYNC_CLK - at_mu((now_mu() & ~0xf) | self.io_update_delay) - self.cpld.io_update.pulse_mu(8) + delay_mu(int64(self.io_update_delay)) + self.cpld.io_update.pulse_mu(8) # assumes 8 mu > t_SYSCLK + at_mu(now_mu() & ~0xf) + if phase_mode != PHASE_MODE_CONTINUOUS: + self.write32(_AD9910_REG_CFR1, 0x00000002) + # future IO_UPDATE will activate + return pow @portable(flags={"fast-math"}) def frequency_to_ftw(self, frequency): @@ -223,8 +314,15 @@ class AD9910: """Returns amplitude scale factor corresponding to given amplitude.""" return int32(round(amplitude*0x3ffe)) + @portable(flags={"fast-math"}) + def pow_to_turns(self, pow): + """Returns the phase in turns corresponding to a given phase offset + word.""" + return pow/0x10000 + @kernel - def set(self, frequency, phase=0.0, amplitude=1.0): + def set(self, frequency, phase=0.0, amplitude=1.0, + phase_mode=_PHASE_MODE_DEFAULT, ref_time=-1): """Set profile 0 data in SI units. .. seealso:: :meth:`set_mu` @@ -232,10 +330,13 @@ class AD9910: :param ftw: Frequency in Hz :param pow: Phase tuning word in turns :param asf: Amplitude in units of full scale + :param phase_mode: Phase mode constant + :param ref_time: Fiducial time stamp in machine units + :return: Resulting phase offset in turns """ - self.set_mu(self.frequency_to_ftw(frequency), - self.turns_to_pow(phase), - self.amplitude_to_asf(amplitude)) + return self.pow_to_turns(self.set_mu( + self.frequency_to_ftw(frequency), self.turns_to_pow(phase), + self.amplitude_to_asf(amplitude), phase_mode, ref_time)) @kernel def set_att_mu(self, att): @@ -352,7 +453,7 @@ class AD9910: IO_UPDATE and SYNC_CLK. The ramp generator is set up to a linear frequency ramp - (dFTW/t_SYNC_CLK=1) and started at a RTIO timestamp. + (dFTW/t_SYNC_CLK=1) and started at a RTIO time stamp. After scanning the alignment, an IO_UPDATE delay midway between two edges should be chosen.