Use phyphox to plot sensor data from your Microcontroller.
The purpose of this library is to use the phyphox app (see www.phyphox.org) to plot sensor data on your phone with the open source app phyphox. In the other direction you can also use this library to access sensor data from your phone to use in your ESP32 project with Micropython.
- ESP 32
Phyphox is an open source app that has been developed at the RWTH Aachen University. It is available on Android and iOS and primarily aims at making the phone's sensors available for physics experiments. However, the app is based on a very flexible file format that defines data sources, visualizations (i.e. values and graphs) and data analysis (from simple formulas to Fourier transforms). This file format also allows to define Bluetooth Low Energy devices to exchange data from and to.
This library generates an experiment configuration in this file format and allows phyphox to conenct to your microcontroller. It directly transfers the configuration (including graph configurations, axis labels, etc.) to phyphox and provides function to submit data to be plotted in phyphox or receive sensor data.
[TBD]
The easiest way to learn how to use this library is by looking at the examples in the examples folder. In most cases, you can simply connect to your Microcontroller running this library by scanning for Bluetooth devices via the "+"-button on the main screen of phyphox.
This is our minimal example. It submits random numbers to phyphox. All you need to do to submit a value to phyphox is including this library, starting the server (i.e. in setup()) and writing your data to the server.
import phyphoxBLE
import time
import random
def main():
p = phyphoxBLE.PhyphoxBLE()
p.start() #Start the BLE server
while True:
randomNumber = random.randint(0,100) #Generate random number in the range 0 to 100
p.write(randomNumber) #Send value to phyphox
time.sleep_ms(500) #Shortly pause before repeating
if __name__ == "__main__":
main()This example shows how you can set a title, category and description as well as how to define graphs and setting axis labels and units. You can define one or multiple views (shown as tabs in phyphox), each of which can hold one or more graphs.
For each graph you need to call setChannel(x, y) with x and y being an index of your data set. This index corresponds to the order of the values that you transfer in a call to server.write while the index 0 is special and corresponds to the timestamp at which phyphox receives the value. At the moment server.write supports up to five values.
For example, let's assume you have the float values foo and bar. You can then call server.write(foo, bar) to send a set with both values. If you call setChannel(0,1), your graph would plot foo on the y axis over time on the x axis. If you call setChannel(2,1), your graph would plot foo on the y axis and bar on the x axis.
Here are some useful methods to create your own experiment:
| Target | Method | Explanation |
|---|---|---|
| Experiment | setTitle(String) | Sets a title for the experiment |
| Experiment | setCategory(String) | Sets a category for the experiment |
| Experiment | setDescription(String) | Sets a description for the experiment |
| Experiment | addView(View) | Adds a view to the corresponding experiment |
| Experiment | addExportSet(ExportSet) | Adds an exportSet to the corresponding experiment |
| View | addElement(Element) | Adds an element to the corresponding view |
| View | setLabel(String) | Sets a label for the view |
| Graph | setLabel(String) | Sets a label for the graph |
| Graph | setUnitX(String) | Sets the unit for x (similar with y) |
| Graph | setLabelX(String) | Sets a label for x (similar with y) |
| Graph | setXPrecision(int) | Sets the amount of digits after the decimal point (similar with y) |
| Graph | setChannel(int, int) | As explained above (1-5) |
| Graph | setStyle(String) | Sets the style. For more possibilities check the wiki |
| Graph | setColor(String) | Sets the line color of the graph (use a 6 digit hexadecimal code) |
| Separator | setHeight(float) | Creates a line to separate parts of the experiment |
| Separator | setColor(String) | Sets the color of the line (use a 6 digit hexadecimal code) |
| Info | setInfo(String) | Sets the infotext |
| Info | setColor(String) | Sets the font color (use a 6 digit hexadecimal code) |
| Value | setLabel(String) | Sets a label for the displayed value |
| Value | setPrecision(int) | Sets the amount of digits after the decimal point |
| Value | setUnit(String) | Sets a unit for the displayed value |
| Value | setColor(String) | Sets the font color (use a 6 digit hexadecimal code) |
| Value | setChannel(int) | As explained above, just with one parameter (1-5) |
| Edit | setLabel(String) | Sets label for the editfield |
| Edit | setUnit(String) | Sets unit |
| Edit | setSigned(bool) | true = signed values allowed |
| Edit | setDecimal(bool) | true = decimal values allowed |
| Edit | setChannel(int) | As explained above, just with one parameter (1-5) |
| ExportSet | setLabel(String) | Sets a label for the exportSet (Used to export to Excel, etc.) |
| ExportData | setLabel(String) | Sets a label for the exportData |
| ExportData | setDatachannel(int) | Defines which channel should be exported for this dataset (1-5) |
| Everything | setXMLAttribute(String) | Custom property e.g. setXMLAttribute("lineWidth="3"") |
If for some reason the app shows you an error in form of "ERROR FOUND: ERR_X", with different values for X, this could be the reason:
- ERR_01: The input was too long
- ERR_02: The value exceeds the upper limit
- ERR_03: The input was not a 6-digit hexadecimal code
- ERR_04: The input does not match with a valid value
If the microcontroller is continiously rebooting, you maybe added too many elements.
The phyphox file format is much more powerful than what is offered by this library's interface. In the example getDataFromSmartphone.ino you can see how a phyphox-file can be used to set up a sensor on the phone and retrieve its data on the microcontroller.
As the phyphox file format is extremely complex and powerful, please refer to the phyphox wiki to learn about it and feel free to contact us if you are stuck or think that a specific aspect of the file format should be easily accessible through our Micropython library.
For now, this library is rather lightweight. Feel free to browse the files to learn about the functions that are already available.
In the future we would like to see...
- Some memory optimization
- Compression for the transfer of the phyphox experiment generated on the microcontroller
- Option to request a larger mtu size
- Addition graph settings
- Proper documentation
If you can help with this, we are happy to receive a pull request. You can contact us via [email protected] if you plan on a large addition to this library and want to make sure that it does not collide with anything we are already working on.
This library has been developed by the phyphox team at the RWTH Aachen University. It is a port of our Arduino BLE library and has been developed by Edward Leier and Marcel Hagedorn.
Contact us any time at [email protected] and learn more about phyphox on https://phyphox.org.
This library is released under the GNU Lesser General Public Licence v3.0 (or newer).
Note that it uses MicroPython and uses code from its Bluetooth examples (specifically ble_advertising.py, which are licenced under the MIT licence as listed at the end of this readme
MicroPython is licenced under the MIT licence.
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