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Usage.md

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Usage

Settings

The default settings are defined in Settings.hpp. They can be modified to change the startup behaviour of the software. Please refer to the file for more details.

WebUI

The software can be controlled with a browser supporting Bluetooth Web API.

After starting the device will activate its Bluetooth connection, and start accepting connections. Note that the Bluetooth interface will deactivate after 5mins of inactivity.

Open f2heal_webui.html found in WebUI folder in a browser to use this feature. A recent version can be on WebUI F2Heal.

Use the connect button to connect to a device.

Untitled

Browsers

Chrome

Successfully tested with Chrome. It might be necessary to enable experimental features by setting the 'enable-experimental-web-platform-features' flag to enabled.

Change this in your browser by going to:

 chrome://flags/#enable-experimental-web-platform-features

BlueFy

On Apple devices the BlueFy Web Browser can also be used

TTL Trigger

In the current setup a TTL trigger can be used to start and stop the device. This can be used for EEG measurement or an extra on-off switch.

Qwiic connector

The onboard Qwiic connector is used to control the TTL Trigger. In the image below, the Qwiic connector is connected with the black-blue-yellow-red cable:

image

The pins used are defined in BoardDefs.hpp. Refer to this image to translate between the nRF and Arduino pins.

Test with Digital Coupler

In the setup below, the TTL is triggered with a parallel port that is connected to a digital coupler. The TTL can be triggered with a digital input from the coupler. The coupler is connected with the VHP board via the Qwiic connector.

image

In the setup above:

  • The LPT Port has 25 pins
  • Pin 18 is used as ground connected with a black wire.
  • Pin 9, being Digital output 7 is made permanently high at 5V as power supply for the digital coupler. Being the red wire.
  • Pin 2, being Digital output 0 is used as stop Signal. Switching it from logical 0 to logical one generates a rising edge, being the stop Signal.
  • Pin 3, being Digital output 1 is used as start Signal. Switching it from logical 0 to logical one generates a rising edge, being the start Signal.

image

Internals

The software will produce a waveform in a random sequence on the different channels according to the settings passed to SStream.

These parameters are defined and documented in SStream.hpp and illustrated below.

image

image

The default settings in Settings.hpp provide with a balanced default:

  • 8 channels

  • Samplerate 46875Hz, long story, tied to SetUpsamplingFactor(1), only touch it if you know what you're doing ;-)

  • Stimulation frequency 250Hz

    • This means that one stimulation sine cycle takes 46875Hz / 250Hz = 187.5 samples

  • Stimulation duration 100ms

    • This means that one stimulation period takes 4687.5 samples

  • Cycle period 1332ms. This leaves 1332ms / 8 = 166.5ms as a maximum for stimulation duration. With a stimulation duration of 100ms this leaves 166.5 - 100 = 66.5ms of silence before the next channel starts

  • Pauze-cyle period 5 & Pauzed cycles 2 : For every 5 cycles 2 will be pauzed, total silence on all channels. So on 5 * 1332ms = 6660ms there will 2 * 1332ms = 2664ms of silence

  • Jitter 23.5% : This is 23.5% of 1332ms / 8 or 39.1ms, so well below the 66.5ms of silence calculated above

Warning: Not all settings make sense. The settings2.ods spreadsheet can be used to verify your settings.

Current used settings preset :

image