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fastino: document/cleanup 

* added documentation on `update`/`hold` mechanism
* mask machine unit values
* cleanup coredevice driver

close #1518
This commit is contained in:
Robert Jördens 2020-09-03 17:42:35 +02:00
parent 1b475bdac4
commit 56aa22caeb
1 changed files with 28 additions and 9 deletions
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37
artiq/coredevice/fastino.py
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@ -1,25 +1,44 @@
"""RTIO driver for the Fastino 32channel, 16 bit, 2.5 MS/s per channel,
streaming DAC.
TODO: Example, describe update/hold
"""
from artiq.language.core import kernel, portable, delay
from artiq.coredevice.rtio import rtio_output, rtio_output_wide, rtio_input_data
from artiq.coredevice.rtio import (rtio_output, rtio_output_wide,
rtio_input_data)
from artiq.language.units import us
from artiq.language.types import TInt32, TList, TFloat
from artiq.language.types import TInt32, TList
class Fastino:
"""Fastino 32-channel, 16-bit, 2.5 MS/s per channel streaming DAC
The RTIO PHY supports staging DAC data before transmitting them by writing
to the DAC RTIO addresses, if a channel is not "held" by setting its bit
using :meth:`set_hold`, the next frame will contain the update. For the
DACs held, the update is triggered explicitly by setting the corresponding
bit using :meth:`set_update`. Update is self-clearing. This enables atomic
DAC updates synchronized to a frame edge.
The `log2_width=0` RTIO layout uses one DAC channel per RTIO address
and a dense RTIO address space. The RTIO words are narrow.
(32 bit compared to 512) and few-channel updates are efficient.
There is the least amount of DAC state tracking in kernels,
at the cost of more DMA and RTIO data.
Other `log2_width` (up to `log2_width=5`) settings pack multiple
(in powers of two) DAC channels into one group and into one RTIO write.
The RTIO data width increases accordingly. The `log2_width`
LSBs of the RTIO address for a DAC channel write must be zero and the
address space is sparse.
If `log2_width` is zero, the :meth:`set_dac`/:meth:`set_dac_mu` interface
must be used. If non-zero, the :meth:`set_group`/:meth:`set_group_mu`
interface must be used.
:param channel: RTIO channel number
:param core_device: Core device name (default: "core")
:param log2_width: Width of DAC channel group (power of two,
see the RTIO PHY for details). If zero, the
:meth:`set_dac`/:meth:`set_dac_mu` interface must be used.
If non-zero, the :meth:`set_group`/:meth:`set_group_mu`
interface must be used. Value must match the corresponding value
see the RTIO PHY for details). Value must match the corresponding value
in the RTIO PHY.
"""
kernel_invariants = {"core", "channel", "width"}
@ -94,7 +113,7 @@ class Fastino:
:param voltage: Voltage in SI Volts.
:return: DAC data word in machine units, 16 bit integer.
"""
return int(round((0x8000/10.)*voltage)) + 0x8000
return (int(round((0x8000/10.)*voltage)) + 0x8000) & 0xffff
@portable
def voltage_group_to_mu(self, voltage, data):