config.rst



Configuration
The configuration file config.py defines how the OhmPi system is assembled and expected to behave. It tells the software how the hardware is set up, cabled and configured.
In certain cases, it also allows you to define hardware specifications, such as the maximum voltage that a specific MUX board can handle.
For general purpose, most specifications can be left on default values.

Warning
Not to be confused with :ref:`settings`. One configuration specified in a config.py file can handle multiple combinations of acquisition settings.


Default configuration
A default version of config.py is provided in the repository.
This file should be edited to customize the configuration following the user's needs and preferences.
A series of default configuration files are available in the configs folder. A simple helper command can help you select the appropriate configuration file depending on your version of the meausurement board and type of MUX boards.
The helper will ask you a few questions and will select the right configuration for your case. It can be called in via the terminal as
.. code-block:: bash

$ python setup_config.py
Still, it is best practice to open the configuration file and check that the parameters are correctly configured.
Updating the configuration file manually is mandatory for custom systems combining different versions of the measurement and MUX boards.

Warning
One should make sure to understand the parameters before altering them. It is also recommended to keep a copy of the default configuration.


Configuration file structure
The configuration is written in a python file structured in a series of dictionaries related to:

OHMPI_CONFIG: the OhmPi instrument information (id of the instrument and default settings).


HARDWARE_CONFIG: the hardware system in which the five different modules 'ctl' (controller), 'tx' (transmitter), 'rx' (receiver), 'mux' (multiplexers), 'pwr' (power).


HARDWARE_CONFIG


Main Key
Module Key
Value


Description
Expected Value
Value description


ctl
model
Controller of the OhmPi system.
raspberry_pi
Defines a Raspberry Pi as controller.


pwr
model
Type of power unit.
pwr_batt
Defines an external battery as power unit.


pwr_dps5005
Defines an external DPS 5005 as power unit


voltage
Defines default output voltage in V.

float, e.g. 12.
Sets 12 V as default voltage.


interface_name


Interface used for communication
with controller.


none
Sets no software communication (e.g. for 'pwr_batt')


modbus
Sets a modubs connection


tx
model
Type of transmitter.
mb_2024_0_2


Load TX defined in
:func:`ohmpi.hardware_components.mb_2024_0_2`


mb_2023_0_X


Load TX defined in
:func:`ohmpi.hardware_components.mb_2023_0_X`


voltage_max
Maximum voltage supported by the TX board [V]

float, e.g. 50.
 

current_max
Maximum current supported by TX board [A]

float, e.g. 0.05
Is function of r_shunt. Can be calculated as 4.80/(50*r_shunt)


r_shunt
Value (in Ohms) of shunt resistor mounted on TX.

float, e.g. 2.
2 Ohms resistor.


interface_name


Name of interface used for communication with
controller


i2c
I2C connector 1


i2c_ext
I2C connector 2


rx
model
Type of transmitter.
mb_2024_0_2


Load RX defined in
:func:`ohmpi.hardware_components.mb_2024_0_2`


mb_2023_0_X


Load RX defined in
:func:`ohmpi.hardware_components.mb_2024_0_2`


latency


Latency in seconds in continuous mode
(related to ADS)


float, e.g. 0.01
10 ms


sampling_rate
Number of samples per second

int, e.g. 50
50 samples per seconds.


interface_name


Name of interface used for communication with
controller


i2c
I2C connector 1


i2c_ext
I2C connector 2


mux
boards


Dictionary containing all MUX boards of the
system and the associated specific
configuration.


mux_id
Dictionary (see table_mux_config)


default


Dictionary containing configuration applicable
to all MUX boards of the systems


default_dict
Dictionary (see table_mux_config)


MUX board general config in HARDWARE_CONFIG


Module Key
Value


Description
Expected Value
Value description


model
Type of Mux board.
mux_2024_0_X


Load RX defined in
:func:`ohmpi.hardware_components.mux_2024_0_X`


mux_2023_0_X


Load RX defined in
:func:`ohmpi.hardware_components.mux_2023_0_X`


electrodes
List of electrodes addressed by the MUX board


array-like,
e.g. range(1,65)


Sets electrode IDs addressed by the MUX board


roles
roles addressed by the MUX board


string, list
of 'A', 'B', 'M', 'N'


or dict, e.g.
{'A':'X','B':'Y',
'M':'XX','N':'YY'}


Sets roles addressed by the MUX board.
If string, MUX addresses only 1 role (for MUX 2023)
For MUX 2024:
* Number of roles defines if MUX set up in 2 or 4 roles mode.
* list or array order determines physical cabling
* dict values rely on annotation on MUX 2024 board

'X', 'Y', 'XX', 'YY'


voltage_max
Maximum injected voltage managed by the MUX board

float, e.g. 50.
Sets maximum voltage to 50 V.


current_max
Maximum current [in A] managed by the MUX board

float, e.g. 3.
Sets maximum current to 3 A.


i2c_ext_tca_address
I2C address of I2C extension
None (default)         |   No I2C extensions cabled.


hex integer, e.g. 0x71
Address of I2C extension


i2c_ext_tca_channel
Channel of the I2C extension

int 0 - 7
Channel used in case I2C extension configured.


MUX 2023 board specific config in HARDWARE_CONFIG


Module Key
Value


Description
Expected Value
Value description


mux_tca_address
I2C address of MUX board


hex integer
0x70 - 0x77


Address of MUX board


MUX 2024 board specific config in HARDWARE_CONFIG


Module Key
Value


Description
Expected Value
Value description


addr1
Physical position of jumper on addr1


string 'up' or 'down


This will compute I2C address of MUX board based on addr1
and addr 2 configuration.


addr2
Physical position of jumper on addr1


string 'up' or 'down


This will compute I2C address of MUX board based on addr1
and addr 2 configuration.


the logging dictionaries divided in:


the MQTT dictionaries divided in: