API reference

class ohmpi.hardware_system.OhmPiHardware(**kwargs)

OhmPiHardware class.

Attributes:

pulses

pwr_state

sp

Methods

compute_tx_volt([pulse_duration, strategy, ...])	Estimates best Tx voltage based on different strategies.
reset_mux()	Switches off all multiplexer relays.
switch_mux(electrodes[, roles, state])	Switches on multiplexer relays for given quadrupole.
test_mux([channel, activation_time])	Interactive method to test the multiplexer.
vab_square_wave(vab, cycle_duration[, ...])	Performs a Vab injection following a square wave and records full waveform data.

calibrate_rx_bias
last_dev
last_iab
last_iab_dev
last_resistance
last_vmn
last_vmn_dev
select_samples

compute_tx_volt(pulse_duration=0.1, strategy='vmax', tx_volt=5.0, vab_max=None, iab_max=None, vmn_max=None, vmn_min=None, polarities=(1, -1), delay=0.05, p_max=None, diff_vab_lim=2.5, n_steps=4)

Estimates best Tx voltage based on different strategies. At first a half-cycle is made for a short duration with a fixed known voltage. This gives us Iab and Rab. We also measure Vmn. A constant c = vmn/iab is computed (only depends on geometric factor and ground resistivity, that doesn’t change during a quadrupole). Then depending on the strategy, we compute which vab to inject to reach the minimum/maximum Iab current or min/max Vmn. This function also compute the polarity on Vmn (on which pin of the ADS1115 we need to measure Vmn to get the positive value).

Parameters:

pulse_durationfloat, optional

Time in seconds for the pulse used to compute Rab.

strategystr, optional

Either: - vmax : compute Vab to reach a maximum Iab without exceeding vab_max - vmin : compute Vab to reach at least vmn_min - constant : apply given Vab

tx_voltfloat, optional

Voltage to apply for guessing the best voltage. 5 V applied by default. If strategy “constant” is chosen, constant voltage to applied is “tx_volt”.

vab_maxfloat, optional

Maximum injection voltage to apply to tx (used by all strategies)

vmn_minfloat, optional

Minimum voltage target for rx (used by vmin strategy)

Returns:

vabfloat

Proposed Vab according to the given strategy.

polarity:

Polarity of VMN relative to polarity of VAB

rabfloat

Resistance between injection electrodes

reset_mux()

Switches off all multiplexer relays.

switch_mux(electrodes, roles=None, state='off', **kwargs)

Switches on multiplexer relays for given quadrupole.

Parameters:

electrodeslist

List of integers representing the electrode ids.

roleslist, optional

List of roles of electrodes, optional

statestr, optional

Either ‘on’ or ‘off’.

test_mux(channel=None, activation_time=1.0)

Interactive method to test the multiplexer.

Parameters:

channeltuple, optional

(electrode_nr, role) to test.

activation_timefloat, optional

Time in seconds during which the relays are activated.

vab_square_wave(vab, cycle_duration, sampling_rate=None, cycles=3, polarity=1, duty_cycle=1.0, append=False)

Performs a Vab injection following a square wave and records full waveform data. Calls in function Vab_pulses.

Parameters:

vab: float

Injection voltage [V]

cycle_duration: float

Duration of one cycle within the square wave (in seconds)

sampling_rate: float, None Default None

Sampling rate for Rx readings

cycles: integer, Default: 3

Number of cycles

polarity: 1, 0 , -1

Starting polarity

duty_cycle: float (0 to 1)

Duty cycle of injection wave

append: bool, optional

Default: False