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[WIP] Decadac fine voltage #826

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[WIP] Decadac fine voltage #826

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e1194f2
WIP add fine voltage to decadac
jenshnielsen Oct 27, 2017
7a33577
correct indent
jenshnielsen Oct 27, 2017
ea1423e
Merge branch 'master' into decadac_fine
astafan8 Sep 14, 2019
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38 changes: 37 additions & 1 deletion qcodes/instrument_drivers/Harvard/Decadac.py
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Original file line number Diff line number Diff line change
Expand Up @@ -200,6 +200,11 @@ def __init__(self, parent, name, channel, min_val=-5, max_val=5):
# Note we will use the older addresses to read the value from the dac
# rather than the newer 'd' command for backwards compatibility
self._volt_val = vals.Numbers(self.min_val, self.max_val)
self.add_parameter("fine_volt",
get_cmd=self._get_fine_voltage,
set_cmd=self._set_fine_voltage,
label="Voltage", unit="V"
)
self.add_parameter("volt", get_cmd=partial(self._query_address,
self._base_addr+9, 1),
get_parser=self._dac_code_to_v,
Expand Down Expand Up @@ -265,6 +270,37 @@ def __init__(self, parent, name, channel, min_val=-5, max_val=5):
set_parser=self._dac_v_to_code,
vals=vals.Numbers(self.min_val, self.max_val))

def _get_fine_voltage(self):
slot = self._parent
if slot.slot_mode.get_latest() not in ['Fine', 'FineCald']:
raise RuntimeError("Cannot get fine voltage unless slot in Fine mode")
if self._channel == 0:
fine_chan = 2
elif self._channel == 1:
fine_chan = 3
else:
raise RuntimeError("Fine mode only works for Chan 0 and 1")
return self.volt.get() + (slot.channels[fine_chan].volt.get()+10)/200

def _set_fine_voltage(self, voltage):
slot = self._parent
if slot.slot_mode.get_latest() not in ['Fine', 'FineCald']:
raise RuntimeError("Cannot get fine voltage unless slot in Fine mode")
if self._channel == 0:
fine_chan = 2
elif self._channel == 1:
fine_chan = 3
else:
raise RuntimeError("Fine mode only works for Chan 0 and 1")
coarse_part = self._dac_code_to_v(self._dac_v_to_code(voltage-0.001))

fine_part = voltage - coarse_part
fine_scaled = fine_part*200-10
print("trying to set to {}, by setting coarse {} and fine {} with total {}".format(voltage,
coarse_part, fine_scaled, coarse_part+fine_part))
self.volt.set(coarse_part)
slot.channels[fine_chan].volt.set(fine_scaled)

def _ramp(self, val, rate, block=True):
"""
Ramp the DAC to a given voltage.
Expand Down Expand Up @@ -383,7 +419,7 @@ def __init__(self, parent, name, slot, min_val=-5, max_val=5):
val_mapping=slot_modes)

# Enable all slots in coarse mode.
self.slot_mode.set(self.SLOT_MODE_DEFAULT)
self.slot_mode.set("Fine")
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@spauka spauka Nov 8, 2017

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Just an FYI that this change will cause issues for us on our experiments.

Perhaps we should add an unknown state that is set when the instrument is initialized, given that there is no (known) way of reading out this value?

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@jenshnielsen jenshnielsen Nov 8, 2017 •
edited by WilliamHPNielsen
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@spauka I know, this is not meant to go in in the current format (hence the [WIP] tag)

Did you see my notification on Slack, If you are using the Decadac driver and do ramping by setting delay and step as in the tutorial here https://github.com/QCoDeS/Qcodes/blob/master/docs/examples/Tutorial.ipynb
it will most likely jump to wrong value at the beginning of the ramp. Affected QCoDeS master is between the 16th of October and Yesterday

This does not affect you if you use the ramping built into the decadac driver.

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@spauka spauka Nov 8, 2017

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Of course, sounds good :) Thought it worth mentioning the possible solution of setting an unknown state, I hadn't been using delays/steps so this hasn't affected me as yet, but will keep this in mind.

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@jenshnielsen jenshnielsen Nov 8, 2017

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Sure, thanks for bringing it up. Better safe than sorry


def write(self, cmd):
"""
Expand Down