Project for "take-home" Arduino-based scope. Binaries for Windows, Mac, Linux, & Arm are available in the "Released versions", get the lastest one here https://github.com/gwiederhecker/arduino_scope/releases!
Disclaimer: This project was entirely based on the Instructable post by RGCO user: https://www.instructables.com/id/Another-Arduino-Oscilloscope/
- Across all the Arduino-based oscilloscopes available online (and there are many out there!), I came across the project by RGCO which has two great advantages:
- The Arduino ADC settings (most important the prescaler factor) are tweaked to run the ADC at maximum speed.
- User interface written in Processing language, which is Java-based and can be easily compiled for various platforms (Windows, Mac, Linux, Arm, Android,...)
- The purpose of this project is to adapdt RGCO original code to be used as an amateur multi-channel oscilloscope for undergraduate students introductory experimental course on alternate-currents. Specifically F429 tought at Unicamp for many STEM majors.
I reproduce here the original features quoted at Instructables.com:
- No extra hardware beyond an Arduino connected to a PC
- Sample rate of up to 77ks/s
- Up to six input channels
- 10-bit precision
- Two vertical ranges (0-5V or 0-1.1V)
- Trigger on rising or falling edge
- Free running or one-shot operation
- Integrated pulse generator
- Display on computer screen using open-source ‘processing’ sketch
On top of these, I would add that this is an extremely cheap scope, even when compared to projects like EspoTek Labrador. Of course it should not perform as well, given the complete lack of an analog front-end.
- For a "take-home" deployment, a couple of features were missing in the original implementation
- Selection of the proper USB port that is connected to the Arduino
- Hability to save the data to a file.
- Compiled versions so students could plug and play to get their analysis going.
- These three items are the major contributions of the this project, when compared to the original post by RGCO.
├── Arduino_Scope_Desktop
│ ├── Arduino_Scope_desktop.pde
│ └── binaries
├── Arduino_code
│ └── Arduino_code.ino
├── Arduino_schematic
│ ├── QUCS_schematic
│ └── protoboard
├── Examples
│ ├── canais_2020-08-18T14:37:13.csv
│ └── load_data.ipynb
├── License.md
├── README.md
└── Screenshots
├── capacitor_loaded_trace.png
├── cursors_example.png
├── save_folder_selection.png
└── serial_port_selection.png- V0.0-alpha : Initial version
- V0.0-beta : Current version - Added cursors and save screenshot feature with TAB key.
- V0.1 : Adapt code to work with Android phones
The lack of an appropriate analog front-end for the ADC poses several issues that must be taken into account when using this as a multi-channel oscilloscope at tens of KHz. A few things that deserve some attention:
- Output impedance of internal signal generator (using arduino PWM)
- ADC settling time that create ghosting effect between channels.
- Using common DC offset to enable positive/negative measurements
- Over the next coupled of months (Oct-Nov 2020), we should post some extensive comparison with commercial oscilloscope in various loading conditions.