How to contribute

OhmPi is an open source system and contributions in terms of hardware and software are welcome. However, in order to maintain the project on tracks and promote exchange and reuse, it is necessary that contributors wishing to develop new software or hardware components follow a few basic steps detailed below. Contributors are also kindly asked to get in touch with the OhmPi developing team.

Developing hardware components

Here is a non exhaustive wish list of new hardware features that are planned/hoped to be developed in the future. Contributors are welcomed to join forces to make this list come true, or propose new ideas by creating a new issue in the Gitlab repository.

Wish list of hardware developments:

Automatic selection of shunt resistors in a set of shunt resistances (hardware)
Add analog low-pass filter on receiver (hardware)
Battery recharge manager for monitoring (hardware)
Multi-channel acquisition (hardware)
Control OhmPi via microcontroller (hardware)

Developing software features

If the new developments purely concern the software (e.g. bug fix, new acquisition strategy, etc.), then please follow the git best practices by first creating an new issue and then create a local branch linked to this issue. Once the new feature is implemented, a pull request can be initiated.

Here is a series of software developments that are planned/hoped:

Sequence generator (software)
Calculate time-variable SP effects (software)
Calculate IP from full-waveform (software)
Pseudo multi-channel acquisition (software)

Software interface to new hardware components

This section is intended for developers of a new hardware component as part of an OhmPi system.

It presents some advices and best practices that should help developing new hardware components to work within an OhmPi system.

Two cases should be distinguished when dealing with hardware development components:

1- Developments of a hardware component that comply with the way the OhmPi Hardware System works. Such developments typically focus on improving an existing component (reduce cost, improve performance, adapt range to specific applications, design with easily available parts…). The newly created hardware component will expose the minimal functionalities required by hardware_system for this type of component.

2- Developments of a hardware component that introduce changes in the way the OhmPi Hardware System works. Such developments do not only focus on improving a single component but also on the way to operate the system. A discussion with developers of the OhmPi_Hardware and OhmPi classes should be initiated at a very early stage to investigate the best ways to design and implement a working solution.

If you are dealing with case 1 or have designed a development path and strategy, you are ready to start.

First the hardware board/device should be conceived and designed. The Ohmpi team recommends that contributors design or import their boards within KiCAD and that both schemas and PCB are shared.

When developing a new component Class, always start your development in a new branch. 1- Create a new python file or make a copy and modify an existing similar component file. All hardware component modules are stored in the ohmpi/hardware_component directory. In the newly created python file, define a new class based on the relevant abstract class of abstract_hardware_components.py. Implement the abstract methods to interact with your hardware. Name the file according to the name of the component. Make sure to place this new python module in the ohmpi/hardware_component directory.

2- Create a new configuration file or make a copy and modify an existing configuration file. All existing config files are stored in the ohmpi/hardware_component directory. In this newly created config file, describe your system including the new component in the HARDWARE_CONFIG dictionary. Name it config_XXX.py where XXX should be replaced by an expression describing the system. Make sure to place your new config file in the ohmpi/configs directory.

3- Create a new script or make a copy and modify of an existing script for testing the component. In this script, write python code where you will conduct the tests of the required functionalities of the new component.

Hardware components API

class ohmpi.hardware_components.abstract_hardware_components.CtlAbstract(**kwargs)

CTlAbstract Class Abstract class for controller

Attributes:

cpu_temperature

class ohmpi.hardware_components.abstract_hardware_components.MuxAbstract(**kwargs)

MUXAbstract Class Abstract class for MUX

Attributes:

barrier

Methods

`switch`([elec_dict, state, bypass_check])	Switch a given list of electrodes with different roles.
`switch_one`([elec, role, state])	Switches one single relay.
`test`(elec_dict[, activation_time])	Method to test the multiplexer.

reset

switch(elec_dict=None, state='off', bypass_check=False)

Switch a given list of electrodes with different roles. Electrodes with a value of 0 will be ignored.

Parameters:

elec_dictdictionary, optional: Dictionary of the form: {role: [list of electrodes]}.
statestr, optional: Either ‘on’ or ‘off’.
bypass_check: bool, optional: Bypasses checks for A==M or A==M or B==M or B==N (i.e. used for rs-check)

abstract switch_one(elec=None, role=None, state=None)

Switches one single relay.

Parameters:

elec
role
statestr, optional: Either ‘on’ or ‘off’.

test(elec_dict, activation_time=1.0)

Method to test the multiplexer.

Parameters:

elec_dictdictionary, optional: Dictionary of the form: {role: [list of electrodes]}.
activation_timefloat, optional: Time in seconds during which the relays are activated.

class ohmpi.hardware_components.abstract_hardware_components.PwrAbstract(**kwargs)

PwrAbstract Class Abstract class for Power module

Attributes:

current
pwr_state
voltage

Methods

battery_voltage
reload_settings
reset_voltage

class ohmpi.hardware_components.abstract_hardware_components.RxAbstract(**kwargs)

RXAbstract Class Abstract class for RX

Attributes:

bias: Gets the RX bias
gain
latency: Gets the Rx latency
sampling_rate
voltage: Gets the voltage VMN in Volts

Methods

gain_auto
reset_gain

property bias: Gets the RX bias

property latency: Gets the Rx latency

abstract property voltage: Gets the voltage VMN in Volts

class ohmpi.hardware_components.abstract_hardware_components.TxAbstract(**kwargs)

TxAbstract Class Abstract class for TX module

Attributes:

current: Gets the current IAB in Amps
gain
injection_duration
latency: Gets the Tx latency
measuring
polarity
pwr_state
tx_bat
voltage: Gets the voltage VAB in Volts

Methods

`inject`([polarity, injection_duration, ...])	Abstract method to define injection.
`voltage_pulse`([voltage, length, polarity])	Generates a square voltage pulse

current_pulse
reset_gain

abstract property current: Gets the current IAB in Amps

abstract inject(polarity=1, injection_duration=None, switch_pwr=False)

Abstract method to define injection.

Parameters:

polarity: int, default 1: Injection polarity, can be eiter 1, 0 or -1.
injection_duration: float, default None: Injection duration in seconds.
switch_pwr: bool: Switch on and off tx.pwr.

property latency: Gets the Tx latency

property voltage: Gets the voltage VAB in Volts

voltage_pulse(voltage=0.0, length=None, polarity=1)

Generates a square voltage pulse

Parameters:

voltage: float, optional: Voltage to apply in volts, tx_v_def is applied if omitted.
length: float, optional: Length of the pulse in seconds
polarity: 1,0,-1: Polarity of the pulse

class ohmpi.hardware_components.mb_2023_0_X.Rx(**kwargs)

RX class

Attributes:

bias: Gets the RX bias
gain
latency: Gets the Rx latency
sampling_rate
voltage: Gets the voltage VMN in Volts

Methods

gain_auto
reset_gain

property voltage: Gets the voltage VMN in Volts

class ohmpi.hardware_components.mb_2023_0_X.Tx(**kwargs)

Tx Class

Attributes:

current: Gets the current IAB in Amps
gain
injection_duration
latency: Gets the Tx latency
measuring
polarity
pwr_state
tx_bat
voltage: Gets the voltage VAB in Volts

Methods

`inject`([polarity, injection_duration, ...])	Abstract method to define injection.
`voltage_pulse`([voltage, length, polarity])	Generates a square voltage pulse

current_pulse
gain_auto
reset_gain

property current: Gets the current IAB in Amps

inject(polarity=1, injection_duration=None, switch_pwr=False)

Abstract method to define injection.

Parameters:

polarity: int, default 1: Injection polarity, can be eiter 1, 0 or -1.
injection_duration: float, default None: Injection duration in seconds.
switch_pwr: bool: Switch on and off tx.pwr.

voltage_pulse(voltage=None, length=None, polarity=1)

Generates a square voltage pulse

Parameters:

voltage: float, optional: Voltage to apply in volts, tx_v_def is applied if omitted.
length: float, optional: Length of the pulse in seconds
polarity: 1,0,-1: Polarity of the pulse

class ohmpi.hardware_components.mb_2024_0_2.Rx(**kwargs)

RX Class

Attributes:

bias: Gets the RX bias
gain
latency: Gets the Rx latency
sampling_rate
voltage: Gets the voltage VMN in Volts

Methods

gain_auto
reset_gain

property voltage: Gets the voltage VMN in Volts

class ohmpi.hardware_components.mb_2024_0_2.Tx(**kwargs)

TX Class

Attributes:

current: Gets the current IAB in Amps
gain
injection_duration
latency: Gets the Tx latency
measuring
polarity
pwr_state
tx_bat
voltage: Gets the voltage VAB in Volts

Methods

`inject`([polarity, injection_duration])	Abstract method to define injection.
`voltage_pulse`([voltage, length, polarity])	Generates a square voltage pulse

current_pulse
gain_auto
reset_gain

inject(polarity=1, injection_duration=None)

Abstract method to define injection.

Parameters:

polarity: int, default 1: Injection polarity, can be eiter 1, 0 or -1.
injection_duration: float, default None: Injection duration in seconds.
switch_pwr: bool: Switch on and off tx.pwr.

class ohmpi.hardware_components.mux_2023_0_X.Mux(**kwargs)

Attributes:

barrier

Methods

`switch`([elec_dict, state, bypass_check])	Switch a given list of electrodes with different roles.
`switch_one`([elec, role, state])	Switches one single relay.
`test`(elec_dict[, activation_time])	Method to test the multiplexer.

reset

switch_one(elec=None, role=None, state=None)

Switches one single relay.

Parameters:

elec
role
statestr, optional: Either ‘on’ or ‘off’.

class ohmpi.hardware_components.mux_2024_0_X.Mux(**kwargs)

Attributes:

barrier

Methods

`switch`([elec_dict, state, bypass_check])	Switch a given list of electrodes with different roles.
`switch_one`([elec, role, state])	Switches one single relay.
`test`(elec_dict[, activation_time])	Method to test the multiplexer.

reset

switch_one(elec=None, role=None, state=None)

Switches one single relay.

Parameters:

elec
role
statestr, optional: Either ‘on’ or ‘off’.

class ohmpi.hardware_components.pwr_batt.Pwr(**kwargs)

Attributes:

current
pwr_state
voltage

Methods

battery_voltage
reload_settings
reset_voltage

class ohmpi.hardware_components.pwr_dps5005.Pwr(**kwargs)

Attributes:

current
pwr_state
voltage

Methods

battery_voltage
current_max
reload_settings
reset_voltage

class ohmpi.hardware_components.raspberry_pi.Ctl(**kwargs)

Attributes:

cpu_temperature