artiq/artiq/coredevice/dds.py
2016-03-29 16:19:03 +08:00

211 lines
7.2 KiB
Python

from artiq.language.core import *
from artiq.language.types import *
from artiq.language.units import *
_PHASE_MODE_DEFAULT = -1
# keep in sync with dds.h
PHASE_MODE_CONTINUOUS = 0
PHASE_MODE_ABSOLUTE = 1
PHASE_MODE_TRACKING = 2
@syscall(flags={"nowrite"})
def dds_init(time_mu: TInt64, bus_channel: TInt32, channel: TInt32) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nowrite"})
def dds_set(time_mu: TInt64, bus_channel: TInt32, channel: TInt32, ftw: TInt32,
pow: TInt32, phase_mode: TInt32, amplitude: TInt32) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nowrite"})
def dds_batch_enter(time_mu: TInt64) -> TNone:
raise NotImplementedError("syscall not simulated")
@syscall(flags={"nowrite"})
def dds_batch_exit() -> TNone:
raise NotImplementedError("syscall not simulated")
class _BatchContextManager:
kernel_constant_attributes = {"core", "core_dds"}
def __init__(self, core_dds):
self.core_dds = core_dds
self.core = self.core_dds.core
@kernel
def __enter__(self):
self.core_dds.dds_batch_enter()
@kernel
def __exit__(self, type, value, traceback):
self.core_dds.dds_batch_exit()
class CoreDDS:
"""Core device Direct Digital Synthesis (DDS) driver.
Gives access to the DDS functionality of the core device.
:param sysclk: DDS system frequency. The DDS system clock must be a
phase-locked multiple of the RTIO clock.
"""
kernel_constant_attributes = {"core", "sysclk", "batch"}
def __init__(self, dmgr, sysclk, core_device="core"):
self.core = dmgr.get(core_device)
self.sysclk = sysclk
self.batch = _BatchContextManager(self)
@kernel
def dds_batch_enter(self):
"""Starts a DDS command batch. All DDS commands are buffered
after this call, until ``batch_exit`` is called.
The time of execution of the DDS commands is the time of entering the
batch (as closely as hardware permits)."""
dds_batch_enter(now_mu())
@kernel
def dds_batch_exit(self):
"""Ends a DDS command batch. All buffered DDS commands are issued
on the bus."""
dds_batch_exit()
class _DDSGeneric:
"""Core device Direct Digital Synthesis (DDS) channel driver.
Controls one DDS channel managed directly by the core device's runtime.
This class should not be used directly, instead, use the chip-specific
drivers such as ``AD9858`` and ``AD9914``.
:param bus: name of the DDS bus device that this DDS is connected to.
:param channel: channel number of the DDS device to control.
"""
kernel_constant_attributes = {
"core", "core_dds", "bus_channel", "channel", "pow_width"
}
def __init__(self, dmgr, bus_channel, channel, core_dds_device="core_dds"):
self.core_dds = dmgr.get(core_dds_device)
self.core = self.core_dds.core
self.bus_channel = bus_channel
self.channel = channel
self.phase_mode = PHASE_MODE_CONTINUOUS
@portable(flags=["fast-math"])
def frequency_to_ftw(self, frequency):
"""Returns the frequency tuning word corresponding to the given
frequency.
"""
return round(int(2, width=64)**32*frequency/self.core_dds.sysclk)
@portable(flags=["fast-math"])
def ftw_to_frequency(self, ftw):
"""Returns the frequency corresponding to the given frequency tuning
word.
"""
return ftw*self.core_dds.sysclk/int(2, width=64)**32
@portable(flags=["fast-math"])
def turns_to_pow(self, turns):
"""Returns the phase offset word corresponding to the given phase
in turns."""
return round(turns*2**self.pow_width)
@portable(flags=["fast-math"])
def pow_to_turns(self, pow):
"""Returns the phase in turns corresponding to the given phase offset
word."""
return pow/2**self.pow_width
@portable
def amplitude_to_asf(self, amplitude):
"""Returns amplitude scale factor corresponding to given amplitude."""
return round(amplitude*0x0fff)
@portable
def asf_to_amplitude(self, asf):
"""Returns the amplitude corresponding to the given amplitude scale
factor."""
return round(amplitude*0x0fff)
@kernel
def init(self):
"""Resets and initializes the DDS channel.
This needs to be done for each DDS channel before it can be used, and
it is recommended to use the startup kernel for this.
This function cannot be used in a batch; the correct way of
initializing multiple DDS channels is to call this function
sequentially with a delay between the calls. 2ms provides a good
timing margin."""
dds_init(now_mu(), self.bus_channel, self.channel)
@kernel
def set_phase_mode(self, phase_mode):
"""Sets the phase mode of the DDS channel. Supported phase modes are:
* ``PHASE_MODE_CONTINUOUS``: the phase accumulator is unchanged when
switching frequencies. The DDS phase is the sum of the phase
accumulator and the phase offset. The only discrete jumps in the
DDS output phase come from changes to the phase offset.
* ``PHASE_MODE_ABSOLUTE``: the phase accumulator is reset when
switching frequencies. Thus, the phase of the DDS at the time of
the frequency change is equal to the phase offset.
* ``PHASE_MODE_TRACKING``: when switching frequencies, the phase
accumulator is set to the value it would have if the DDS had been
running at the specified frequency since the start of the
experiment.
"""
self.phase_mode = phase_mode
@kernel
def set_mu(self, frequency, phase=0, phase_mode=_PHASE_MODE_DEFAULT,
amplitude=0x0fff):
"""Sets the DDS channel to the specified frequency and phase.
This uses machine units (FTW and POW). The frequency tuning word width
is 32, whereas the phase offset word width depends on the type of DDS
chip and can be retrieved via the ``pow_width`` attribute. The amplitude
width is 12.
:param frequency: frequency to generate.
:param phase: adds an offset, in turns, to the phase.
:param phase_mode: if specified, overrides the default phase mode set
by ``set_phase_mode`` for this call.
"""
if phase_mode == _PHASE_MODE_DEFAULT:
phase_mode = self.phase_mode
dds_set(now_mu(), self.bus_channel, self.channel,
frequency, phase, phase_mode, amplitude)
@kernel
def set(self, frequency, phase=0.0, phase_mode=_PHASE_MODE_DEFAULT,
amplitude=1.0):
"""Like ``set_mu``, but uses Hz and turns."""
self.set_mu(self.frequency_to_ftw(frequency),
self.turns_to_pow(phase), phase_mode,
self.amplitude_to_asf(amplitude))
class AD9858(_DDSGeneric):
"""Driver for AD9858 DDS chips. See ``_DDSGeneric`` for a description
of the functionality."""
pow_width = 14
class AD9914(_DDSGeneric):
"""Driver for AD9914 DDS chips. See ``_DDSGeneric`` for a description
of the functionality."""
pow_width = 16