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ad53xx improvements (#1445)

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* ad53xx: voltage_to_mu() validation & documentation (closes #1443, #1444)
The voltage input (float) is checked for validity. If we need more
speed, we may want to check the DAC-code for over/underflow instead.

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>

* ad53xx documentation: voltage_to_mu is only valid for 16-bit DACs

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>

* AD53xx: add voltage_to_mu method (closes #1341)

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>

* ad53xx: improve voltage_to_mu performance
Interger comparison is faster than floating point math.

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>

* AD53xx: voltage_to_mu method now uses attribute values

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>

* Fixup RELEASE_NOTES.rst

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>

* ad53xx: documentation improvements

voltage_to_mu return value
14-bit DAC support

Signed-off-by: Marius Weber <marius.weber@physics.ox.ac.uk>
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Marius Weber 2020-05-08 18:23:43 +01:00 committed by GitHub
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commit b3b6cb8efe
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2 changed files with 27 additions and 3 deletions
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1
RELEASE_NOTES.rst
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@ -11,6 +11,7 @@ Highlights:
* Performance improvements:
- #1432: SERDES TTL inputs can now detect edges on pulses that are shorter
than the RTIO period
* Zotino now exposes `voltage_to_mu()`
Breaking changes:

29
artiq/coredevice/ad53xx.py
View File

@ -80,21 +80,30 @@ def ad53xx_cmd_read_ch(channel, op):
return AD53XX_CMD_SPECIAL | AD53XX_SPECIAL_READ | (op + (channel << 7))
# maintain function definition for backward compatibility
@portable
def voltage_to_mu(voltage, offset_dacs=0x2000, vref=5.):
"""Returns the DAC register value required to produce a given output
"""Returns the 16-bit DAC register value required to produce a given output
voltage, assuming offset and gain errors have been trimmed out.
The 16-bit register value may also be used with 14-bit DACs. The additional
bits are disregarded by 14-bit DACs.
Also used to return offset register value required to produce a given
voltage when the DAC register is set to mid-scale.
An offset of V can be used to trim out a DAC offset error of -V.
:param voltage: Voltage
:param voltage: Voltage in SI units.
Valid voltages are: [-2*vref, + 2*vref - 1 LSB] + voltage offset.
:param offset_dacs: Register value for the two offset DACs
(default: 0x2000)
:param vref: DAC reference voltage (default: 5.)
:return: The 16-bit DAC register value
"""
return int(round(0x10000*(voltage/(4.*vref)) + offset_dacs*0x4))
code = int(round((1 << 16) * (voltage / (4. * vref)) + offset_dacs * 0x4))
if code < 0x0 or code > 0xffff:
raise ValueError("Invalid DAC voltage!")
return code
class _DummyTTL:
@ -366,3 +375,17 @@ class AD53xx:
self.core.break_realtime()
self.write_offset_mu(channel, 0x8000-offset_err)
self.write_gain_mu(channel, 0xffff-gain_err)
@portable
def voltage_to_mu(self, voltage):
"""Returns the 16-bit DAC register value required to produce a given
output voltage, assuming offset and gain errors have been trimmed out.
The 16-bit register value may also be used with 14-bit DACs. The
additional bits are disregarded by 14-bit DACs.
:param voltage: Voltage in SI units.
Valid voltages are: [-2*vref, + 2*vref - 1 LSB] + voltage offset.
:return: The 16-bit DAC register value
"""
return voltage_to_mu(voltage, self.offset_dacs, self.vref)