def __init__(self):
self._device = FtdiChip(DESCRIPTION)
def __init__(self):
self._device = FtdiChip(DESCRIPTION)
class MuonlabII(object):
"""Access Muonlab II hardware.
Instantiate this class to get access to connected Muonlab II hardware.
The hardware device is opened during instantiation.
"""
_device = None
# Yes, really, HV1 and 2 are reversed
_address = {'HV_1': 2,
'HV_2': 1,
'THR_1': 3,
'THR_2': 4,
'MEAS': 5}
def __init__(self):
self._device = FtdiChip(DESCRIPTION)
def __del__(self):
"""Cleanly shut down muonlab hardware."""
if self._device and not self._device.closed:
self.set_pmt1_voltage(0)
self.set_pmt2_voltage(0)
self._device.close()
def _write_setting(self, setting, data):
"""Write setting to device.
:param setting: string specifying the setting to write. Must be
one of HV_1 (for PMT 1 high voltage), HV_2 (for PMT 2 high
voltage), THR_1 (for PMT 1 threshold), THR_2 (for PMT 2
threshold) or MEAS (for type of measurement).
:param data: the raw data byte to write to the device.
For a high voltage setting, the data byte values (in the range of
0x00 - 0xff) are mapped linearly to 300 - 1500 V. For a threshold
setting, the data byte values (0x00 - 0xff) are linearly mapped to
0 mV - 1200 mV.
The type of measurement can be set using only 4 bits. They must
be 0b1111 for a muon lifetime measurement. Any other value will
select a coincidence time difference measurement.
"""
if setting not in self._address:
raise TypeError("Unkown setting: %s" % setting)
else:
address_bits = self._address[setting]
high_byte = (1 << 7) | (address_bits << 4) | ((data & 0xf0) >> 4)
low_byte = (address_bits << 4) | (data & 0x0f)
if setting == 'MEAS':
# Measurement type can be selected using only 1 byte
command = chr(low_byte)
else:
command = array('B', [high_byte, low_byte]).tostring()
self._device.write(command)
def set_pmt1_voltage(self, voltage):
"""Set high voltage for PMT 1.
:param voltage: integer. Values are clipped to a 300 - 1500 V
range.
"""
voltage_byte = map_setting(voltage, 300, 1500, 0x00, 0xff)
self._write_setting('HV_1', voltage_byte)
def set_pmt2_voltage(self, voltage):
"""Set high voltage for PMT 2.
:param voltage: integer. Values are clipped to a 300 - 1500 V
range.
"""
voltage_byte = map_setting(voltage, 300, 1500, 0x00, 0xff)
self._write_setting('HV_2', voltage_byte)
def set_pmt1_threshold(self, threshold):
"""Set threshold for PMT 1.
Events with a signal strength below the specified threshold will
be ignored as noise.
:param threshold: integer. Values are clipped to a 0 - 1200 mV
range.
"""
threshold_byte = map_setting(threshold, 0, 1200, 0x00, 0xff)
self._write_setting('THR_1', threshold_byte)
def set_pmt2_threshold(self, threshold):
"""Set threshold for PMT 2.
Events with a signal strength below the specified threshold will
be ignored as noise.
:param threshold: integer. Values are clipped to a 0 - 1200 mV
range.
"""
threshold_byte = map_setting(threshold, 0, 1200, 0x00, 0xff)
self._write_setting('THR_2', threshold_byte)
def select_lifetime_measurement(self):
"""Select lifetime measurement mode."""
self._write_setting('MEAS', 0xff)
def select_coincidence_measurement(self):
"""Select coincidence time difference measurement mode."""
self._write_setting('MEAS', 0x00)
def flush_device(self):
"""Flush device output buffers.
To completely clear out outdated measurements when changing
parameters, call this method. All data received after this method
was called is really newly measured.
"""
self._device.flush()
def read_lifetime_data(self):
"""Read lifetime data from detector.
Raises ValueError when corrupt data is received.
:returns: list of lifetime measurements
"""
data = self._device.read()
if data:
lifetimes = []
#for word_value in data[::2]:
for i in range(0, len(data), 2):
high_byte, low_byte = ord(data[i]), ord(data[i + 1])
# sanity checks
if not (high_byte & 0x80):
raise ValueError(
"Corrupt lifetime data (high byte bit flag not set)")
if (low_byte & 0x80):
raise ValueError(
"Corrupt lifetime data (low byte bit flag set)")
adc_value = ((high_byte & 0x3f) << 6) | (low_byte & 0x3f)
lifetime = LIFETIME_SCALE * adc_value
lifetimes.append(lifetime)
return lifetimes
else:
return []
def read_coincidence_data(self):
"""Read coincidence data from detector.
Raises ValueError when corrupt data is received.
:returns: list of coincidence time difference measurements
"""
data = self._device.read()
if data:
deltatimes = []
#for word_value in data[::2]:
for i in range(0, len(data), 2):
high_byte, low_byte = ord(data[i]), ord(data[i + 1])
det1_isfirsthit = bool(high_byte & 0x40)
det2_isfirsthit = bool(low_byte & 0x40)
# sanity checks
if not (high_byte & 0x80):
raise ValueError("Corrupt coincidence data "
"(high byte bit flag not set)")
if (low_byte & 0x80):
raise ValueError(
"Corrupt coincidence data (low byte bit flag set)")
if not det1_isfirsthit and not det2_isfirsthit:
raise ValueError(
"Corrupt coincidence data (no hit first flag set)")
adc_value = ((high_byte & 0x3f) << 6) | (low_byte & 0x3f)
deltatime = COINCIDENCE_TIMEDELTA_SCALE * adc_value
if det2_isfirsthit and not det1_isfirsthit:
deltatime *= -1
deltatimes.append((deltatime, det1_isfirsthit,
det2_isfirsthit))
return deltatimes
else:
return []
class MuonlabII(object):
"""Access Muonlab II hardware.
Instantiate this class to get access to connected Muonlab II hardware.
The hardware device is opened during instantiation.
"""
_device = None
# Yes, really, HV1 and 2 are reversed
_address = {'HV_1': 2, 'HV_2': 1, 'THR_1': 3, 'THR_2': 4, 'MEAS': 5}
def __init__(self):
self._device = FtdiChip(DESCRIPTION)
def __del__(self):
"""Cleanly shut down muonlab hardware."""
if self._device and not self._device.closed:
self.set_pmt1_voltage(0)
self.set_pmt2_voltage(0)
self._device.close()
def _write_setting(self, setting, data):
"""Write setting to device.
:param setting: string specifying the setting to write. Must be
one of HV_1 (for PMT 1 high voltage), HV_2 (for PMT 2 high
voltage), THR_1 (for PMT 1 threshold), THR_2 (for PMT 2
threshold) or MEAS (for type of measurement).
:param data: the raw data byte to write to the device.
For a high voltage setting, the data byte values (in the range of
0x00 - 0xff) are mapped linearly to 300 - 1500 V. For a threshold
setting, the data byte values (0x00 - 0xff) are linearly mapped to
0 mV - 1200 mV.
The type of measurement can be set using only 4 bits. They must
be 0b1111 for a muon lifetime measurement. Any other value will
select a coincidence time difference measurement.
"""
if setting not in self._address:
raise TypeError("Unkown setting: %s" % setting)
else:
address_bits = self._address[setting]
high_byte = (1 << 7) | (address_bits << 4) | ((data & 0xf0) >> 4)
low_byte = (address_bits << 4) | (data & 0x0f)
if setting == 'MEAS':
# Measurement type can be selected using only 1 byte
command = chr(low_byte)
else:
command = array('B', [high_byte, low_byte]).tostring()
self._device.write(command)
def set_pmt1_voltage(self, voltage):
"""Set high voltage for PMT 1.
:param voltage: integer. Values are clipped to a 300 - 1500 V
range.
"""
voltage_byte = map_setting(voltage, 300, 1500, 0x00, 0xff)
self._write_setting('HV_1', voltage_byte)
def set_pmt2_voltage(self, voltage):
"""Set high voltage for PMT 2.
:param voltage: integer. Values are clipped to a 300 - 1500 V
range.
"""
voltage_byte = map_setting(voltage, 300, 1500, 0x00, 0xff)
self._write_setting('HV_2', voltage_byte)
def set_pmt1_threshold(self, threshold):
"""Set threshold for PMT 1.
Events with a signal strength below the specified threshold will
be ignored as noise.
:param threshold: integer. Values are clipped to a 0 - 1200 mV
range.
"""
threshold_byte = map_setting(threshold, 0, 1200, 0x00, 0xff)
self._write_setting('THR_1', threshold_byte)
def set_pmt2_threshold(self, threshold):
"""Set threshold for PMT 2.
Events with a signal strength below the specified threshold will
be ignored as noise.
:param threshold: integer. Values are clipped to a 0 - 1200 mV
range.
"""
threshold_byte = map_setting(threshold, 0, 1200, 0x00, 0xff)
self._write_setting('THR_2', threshold_byte)
def select_lifetime_measurement(self):
"""Select lifetime measurement mode."""
self._write_setting('MEAS', 0xff)
def select_coincidence_measurement(self):
"""Select coincidence time difference measurement mode."""
self._write_setting('MEAS', 0x00)
def flush_device(self):
"""Flush device output buffers.
To completely clear out outdated measurements when changing
parameters, call this method. All data received after this method
was called is really newly measured.
"""
self._device.flush()
def read_lifetime_data(self):
"""Read lifetime data from detector.
Raises ValueError when corrupt data is received.
:returns: list of lifetime measurements
"""
data = self._device.read()
if data:
lifetimes = []
#for word_value in data[::2]:
for i in range(0, len(data), 2):
high_byte, low_byte = ord(data[i]), ord(data[i + 1])
# sanity checks
if not (high_byte & 0x80):
raise ValueError(
"Corrupt lifetime data (high byte bit flag not set)")
if (low_byte & 0x80):
raise ValueError(
"Corrupt lifetime data (low byte bit flag set)")
adc_value = ((high_byte & 0x3f) << 6) | (low_byte & 0x3f)
lifetime = LIFETIME_SCALE * adc_value
lifetimes.append(lifetime)
return lifetimes
else:
return []
def read_coincidence_data(self):
"""Read coincidence data from detector.
Raises ValueError when corrupt data is received.
:returns: list of coincidence time difference measurements
"""
data = self._device.read()
if data:
deltatimes = []
#for word_value in data[::2]:
for i in range(0, len(data), 2):
high_byte, low_byte = ord(data[i]), ord(data[i + 1])
det1_isfirsthit = bool(high_byte & 0x40)
det2_isfirsthit = bool(low_byte & 0x40)
# sanity checks
if not (high_byte & 0x80):
raise ValueError("Corrupt coincidence data "
"(high byte bit flag not set)")
if (low_byte & 0x80):
raise ValueError(
"Corrupt coincidence data (low byte bit flag set)")
if not det1_isfirsthit and not det2_isfirsthit:
raise ValueError(
"Corrupt coincidence data (no hit first flag set)")
adc_value = ((high_byte & 0x3f) << 6) | (low_byte & 0x3f)
deltatime = COINCIDENCE_TIMEDELTA_SCALE * adc_value
if det2_isfirsthit and not det1_isfirsthit:
deltatime *= -1
deltatimes.append(
(deltatime, det1_isfirsthit, det2_isfirsthit))
return deltatimes
else:
return []
