Experiment control and others

Overview

FPGA controllers and auxiliary devices are an essential part of experiment automation: from nanosecond real-time timing to relay switching, Quatm provides a unified control interface. ADwin, NI-FPGA, Red Pitaya and several other brands are currently supported.

ADwin

Overview

ADwin is a family of real-time controllers from Jaeger Computergesteuerte Messtechnik, based on an FPGA/DSP architecture, that executes real-time tasks independently of the PC operating system.

How it works

PC (Quatm)                    ADwin (real-time)
┌──────────┐    PCI/USB    ┌──────────────┐
│ experiment│ ←──────────→ │ ADbasic proc │
│   .py     │  Par/Data    │ ns timing+acq│
└──────────┘               └──────────────┘

Quatm experiment scripts read and write parameters and data arrays through the ADwin driver, interacting with the ADbasic process running on the ADwin. The timing-critical parts execute on the ADwin hardware, while the Python side handles parameter setting and result readout.

Initialization

from quatm.drivers.fpga import ADwin

# Connect to ADwin (PCI bus)
adw = ADwin(device_number=1)

# Load and start the ADbasic process
adw.load_process("experiment_sequence.TB1")
adw.start_process()

# Set experiment parameters
adw.set_par(1, 100_000)     # Par_1 = 100 µs cooling time
adw.set_par(2, 50)          # Par_2 = 50 cycles
adw.set_par(3, 10_000)      # Par_3 = 10 ms detection time

# Start one experiment sequence (triggered by an event in ADbasic)
adw.trigger()

# Read acquired data
photons = adw.get_data(1, data_length=1000)  # Read photon counts from Data_1

Key methods

Typical ADbasic process structure

' ADbasic code snippet — experiment timing
Init:
  Par_1 = 100000   ' Cooling time (µs)
  Par_2 = 50       ' Number of cycles
Event:
  For i = 1 To Par_2
    P2_DAC(1, 5000)   ' Set AOM power
    P2_DAC(2, 800)    ' Set magnetic field
    ' ... wait, acquire, switch ...
  Next i

Device configuration

"fpga": {
    "type": "local",
    "module": "quatm.drivers.fpga",
    "class": "ADwin",
    "arguments": {"device_number": 1},
}

Exception:

• quatm.drivers.fpga.adwin.AdWinDriverError(message)

  class quatm.drivers.fpga.adwin.AdWinDriverError(Exception):
      pass
  

quatm.drivers.fpga.client module

Class:

• quatm.drivers.fpga.client.AdWinClient(experiment, simulating=None)

  class quatm.drivers.fpga.client.AdWinClient(object):
      def filter_cmdlist(self, combinetime=1e-08):
          pass
  
      def push(self, time, command, value, combinetime=1e-09):
          pass
  
      def start_realtime(self, processortime=0, repetitions=1):
          pass
  
      def stop(self):
          pass
  

quatm.drivers.fpga.units module

NI-FPGA LabVIEW FPGA modular instruments

from quatm.drivers.NI.ni_fpga import NIFPGA

fpga = NIFPGA(resource_name="RIO0", bitfile="custom_logic.lvbitx")
fpga.run()
fpga.write_control("pulse_width", 100)        # ns
fpga.write_control("trigger_delay", 50)
fpga.read_indicator("photon_count")

Conrad relay board

from quatm.drivers.Conrad.base import RelayBoard

rb = RelayBoard(conn="/dev/ttyUSB0", start_addr=0)
rb.set_relay(relay=0, state=True)
rb.set_relay(relay=3, state=False)
rb.write_byte(0b10101010)