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phaser: Improve documentation of DAC settings

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1. Clarify which features require additional configuration via the `dac`
   constructor argument.
2. Document when DAC settings apply immediatly/are staged.
3. Document how staged DAC settings may be applied
4. Calrify operation of `dac_sync`

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>
This commit is contained in:
Marius Weber 2021-05-08 13:11:51 +01:00
parent f97baa8aec
commit 043c9c20d7
1 changed files with 48 additions and 11 deletions
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59
artiq/coredevice/phaser.py
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@ -86,7 +86,8 @@ class Phaser:
LVDS bus operating at 1 Gb/s per pin pair and processed in the DAC (Texas
Instruments DAC34H84). On the DAC 2x interpolation, sinx/x compensation,
quadrature modulator compensation, fine and coarse mixing as well as group
delay capabilities are available.
delay capabilities are available. If desired, these features my be
configured via the `dac` dictionary.
The latency/group delay from the RTIO events setting
:class:`PhaserOscillator` or :class:`PhaserChannel` DUC parameters all the
@ -574,7 +575,18 @@ class Phaser:
@kernel
def dac_sync(self):
"""Trigger DAC synchronisation for both output channels.
If the DAC-NCO is enabled, this applies NCO frequency changes."""
The DAC sif_sync is de-asserts, then asserted. The synchronisation is
triggered on assertion.
By default, the fine-mixer (NCO) and QMC are synchronised. This
includes applying the latest register settings.
The synchronisation sources may be configured through the `syncsel_x`
fields in the `dac` configuration dictionary (see `__init__()`).
.. note:: Synchronising the NCO clears the phase-accumulator
"""
config1f = self.dac_read(0x1f)
delay(.1*ms)
self.dac_write(0x1f, config1f & ~int32(1 << 1))
@ -584,12 +596,13 @@ class Phaser:
def set_dac_cmix(self, fs_8_step):
"""Set the DAC coarse mixer frequency for both channels
Use of the coarse mixer requires the DAC mixer to be enabled. The mixer
can be configured via the `dac` configuration dictionary (see
`__init__()`).
The selected coarse mixer frequency becomes active without explicit
synchronisation.
Use of the coarse mixer requires the DAC mixer to be enabled. The mixer
can be configured via the `dac` device_db entries.
:param fs_8_step: coarse mixer frequency shift in 125 MHz steps. This
should be an integer between -3 and 4 (inclusive).
"""
@ -813,10 +826,12 @@ class PhaserChannel:
@kernel
def set_nco_frequency_mu(self, ftw):
"""Set the NCO frequency.
The frequency is only applied after DAC synchronisation.
Use of the NCO requires the DAC mixer to be enabled. The mixer can be
configured via the `dac` device_db entries.
This method stages the new NCO frequency, but does not apply it.
Use of the DAC-NCO requires the DAC mixer and NCO to be enabled. These
can be configured via the `dac` configuration dictionary (see
`__init__()`).
:param ftw: NCO frequency tuning word (32 bit)
"""
@ -826,10 +841,12 @@ class PhaserChannel:
@kernel
def set_nco_frequency(self, frequency):
"""Set the NCO frequency in SI units.
The frequency is only applied after DAC synchronisation.
Use of the NCO requires the DAC mixer to be enabled. The mixer can be
configured via the `dac` device_db entries.
This method stages the new NCO frequency, but does not apply it.
Use of the DAC-NCO requires the DAC mixer and NCO to be enabled. These
can be configured via the `dac` configuration dictionary (see
`__init__()`).
:param frequency: NCO frequency in Hz (passband from -400 MHz
to 400 MHz, wrapping around at +- 500 MHz)
@ -841,6 +858,16 @@ class PhaserChannel:
def set_nco_phase_mu(self, pow):
"""Set the NCO phase offset.
By default, the new NCO phase applies on completion of the SPI
transfer. This also causes a staged NCO frequency to be applied.
Different triggers for applying nco settings may be configured through
the `syncsel_mixerxx` fields in the `dac` configuration dictionary (see
`__init__()`).
Use of the DAC-NCO requires the DAC mixer and NCO to be enabled. These
can be configured via the `dac` configuration dictionary (see
`__init__()`).
:param pow: NCO phase offset word (16 bit)
"""
self.phaser.dac_write(0x12 + self.index, pow)
@ -849,6 +876,16 @@ class PhaserChannel:
def set_nco_phase(self, phase):
"""Set the NCO phase in SI units.
By default, the new NCO phase applies on completion of the SPI
transfer. This also causes a staged NCO frequency to be applied.
Different triggers for applying nco settings may be configured through
the `syncsel_mixerxx` fields in the `dac` configuration dictionary (see
`__init__()`).
Use of the DAC-NCO requires the DAC mixer and NCO to be enabled. These
can be configured via the `dac` configuration dictionary (see
`__init__()`).
:param phase: NCO phase in turns
"""
pow = int32(round(phase*(1 << 16)))