Did you ever have the need to display data from a microcontroller on a dashboard, and spent more time developing (and fixing) your dashboard software, than actually working on your MCU project?
Well, I did, multiple times. Let me put you in context, I participate in several CanSat competition programs through KA'AN SAT, a representative team at my university. A CanSat is “a simulation of a real satellite, integrated within the volume and shape of a soft drink can” (European Space Agency, more info). One of the main tasks in these competitions is to develop software for the ground station. The ground station software (GSS) receives telemetry from the CanSat in real time through a serial device (generally a XBee), displays it and exports it to a CSV/Excel file for post-mission analysis. From the start, we developed the GSS with Qt to support multiple operating systems (in case that one of our computers experienced problems during the competition) and because Qt/QML is very convenient for developing eye-catching user interfaces. Here is a screenshot of the 2019 ground station software, and a photo of the GSS running & displaying telemetry during the CUCEI CanSat competition:
If you are interested, the source code for the 2019 GSS is available here. The software worked quite well for all its intents & purposes (we got the first place after all).
The problems came half a year later, when I found myself working on multiple projects that required some kind of data acquisition with serial devices. For example, some members of ROCH (another representative team in our university, which participates in the NASA Human Rover Exploration Challenge) wanted to integrate our GSS with their rover as a side-project during quarantine. The result was disastrous; I got a call late at night and we ended up pulling an all-nighter to come up with a way to adapt the GSS with the telemetry that they were receiving. Finally, the software worked, but the UI integration was horrible & data export was not really functional (see the screenshot below to get an idea):
Both projects (the CanSat and the rover) had a similar telemetry format (sensor readings & OBC status data separated with commas). However, the information itself had a different order.
After that experience, I decided that I had enough of writing separate dashboard software for every project that I got involved with. I needed to come up with a way to have the same dashboard/GSS software to work with all projects, without the need of modifying the GSS code at the last minute. The initial solution that I came up with was to create a JSON-based communication protocol between the GSS and the microcontroller, and thus Serial Studio was born (its initial name was SigLAB, but I changed my mind later). Basically, the microcontroller sends the following information through the serial port:
All this information can be easily represented in a JSON document, for example: { "t":"KAANSATQRO", "g":[ { "t":"Mission Status", "d":[ { "t":"Runtime", "v":"%value%", "u":"ms" }, { "t":"Packet count", "v":"%value%" }, { "t":"Battery voltage", "v":"%value%", "g":true, "u":"V" } ] }, { "t":"Sensor Readings", "d":[ { "t":"Temperature", "v":"%value%", "g":true, "u":"°C" }, { "t":"Altitude", "v":"%value%", "u":"m" }, { "t":"Pressure", "v":"%value%", "u":"KPa", "g":true }, { "t":"External Temperature", "v":"%value%", "g":true, "u":"°C" }, { "t":"Humidity", "v":"%9", "g":true, "u":"%value%" } ] } ] }
As you can see, we have the following structure:
A group consists of values that are closely related to each other, for example:
On the other hand, datasets represent what each individual value means, and what we should do with it. On Serial Studio, this information is displayed in the following manner:
As you can probably deduce, each “window” corresponds to a group in our JSON document (I hid the graphs in the screenshot to avoid confusion).
This approach works beautifully for small projects. However, for more complex projects, creating and sending a large JSON document through serial (or through radio signals, and then through a serial port) becomes quite problematic. The solution? Load the same JSON document from your computer, instruct the microcontroller to send ONLY the sensor/data readings & let Serial Studio figure out the rest by using the indices of each received value in a comma-separated data frame. Doing so lets you have the best from both worlds:
A JSON “map” document looks like this: { "t":"%1", "g":[ { "t":"Mission Status", "d":[ { "t":"Runtime", "v":"%2", "u":"ms" }, { "t":"Packet count", "v":"%3" }, { "t":"Battery voltage", "v":"%4", "g":true, "u":"V", "w":"bar", "min":3.6, "max":4.3 } ] }, { "t":"Sensor Readings", "d":[ { "t":"Temperature", "v":"%5", "g":true, "u":"°C", "w":"bar", "min":0, "max":80 }, { "t":"Altitude", "v":"%6", "u":"m", "w":"bar", "min":0, "max":3000 }, { "t":"Pressure", "v":"%7", "u":"KPa", "g":true, "w":"bar", "min":54, "max":102 }, { "t":"External Temperature", "v":"%8", "g":true, "u":"°C", "w":"bar", "min":0, "max":80 }, { "t":"Humidity", "v":"%9", "g":true, "u":"%", "w":"bar", "min":0, "max":100 } ] }, { "t":"GPS", "w":"map", "d":[ { "t":"GPS Time", "v":"%10" }, { "t":"Longitude", "v":"%11", "u":"°E", "w":"lon" }, { "t":"Latitude", "v":"%12", "u":"°N", "w":"lat" }, { "t":"Altitude", "v":"%13", "u":"m" }, { "t":"No. Sats", "v":"%14" } ] }, { "t":"Accelerometer", "w":"accelerometer", "d":[ { "t":"X", "v":"%15", "u":"m/s^2", "g":true, "w":"x" }, { "t":"Y", "v":"%16", "u":"m/s^2", "g":true, "w":"y" }, { "t":"Z", "v":"%17", "u":"m/s^2", "g":true, "w":"z" } ] }, { "t":"Gyroscope", "w":"gyro", "d":[ { "t":"X", "v":"%18", "u":"°", "g":true, "w":"yaw" }, { "t":"Y", "v":"%19", "u":"°", "g":true, "w":"roll" }, { "t":"Z", "v":"%20", "u":"°", "g":true, "w":"pitch" } ] } ] } As you can guess, Serial Studio will replace the %1,%2,%3,...,%20 values with the values at the corresponding index in a comma-separated data frame. The corresponding sprintf() format sent by the microcontroller for the given JSON map is: /*KAANSATQRO,%s,%s,%s,%s,%s,%s,%,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s,%s*/ You may have noticed some "w" keys in some places, these are used to build widgets (which are explained here). Finally, here is the obligatory GIF showing the usage of Serial Studio:
Pretty cool, right? If you are interested in using Serial Studio for your projects, here are the relevant links:
The prebuilt binaries/installers for Windows, macOS & GNU/Linux are available through GitHub releases: https://github.com/Serial-Studio/Serial-Studio/releases/ Minimal example (with Arduino)
Suppose that we want to graph the an ADC reading with an Arduino & export the data to a CSV table. Here is the Arduino code:
#define ADC_PIN A0 void setup() { // Initialize Serial port at 9600 bauds Serial.begin(9600); // Configure analog input pinMode(ADC_PIN, INPUT); } void loop() { // Read voltage @ ADC_PIN int adc_value = analogRead(ADC_PIN); float voltage = adc_value * (5.0 / 1023.0); // Send current ms & reading through serial Serial.print("/*"); // Frame start sequence [/*] Serial.print(millis()); // Add MCU runtime [ms] Serial.print(","); // Separator character [,] Serial.print(voltage); // Add voltage [V] Serial.print("*/"); // Frame finish sequence [*/] // Wait 50 ms delay(50); } Deploy this code to your Arduino and create a JSON file with the following contents: { "t":"Minimal Example", "g":[ { "t":"MCU Status", "d":[ { "t":"Runtime", "v":"%1", "u":"ms" }, { "t":"ADC reading", "v":"%2", "g":true, "u":"V", "w":"bar", "min":0, "max":5 } ] } ] } Open Serial Studio & import the JSON file into Serial Studio by selecting the "manual" radio button in the top-left corner of the app & clicking on the "Change map file" button. Finally, select the appropriate COM port. If everything goes well, you should see a screen similar to this one:
If you click on the "Open current CSV" button, you will be able to see all the received information in an Excel/Calc table:
If you have any doubts, ideas or bug reports, feel free to add a comment, contact me or open up an issue at GitHub. Hopefully some random person on the internet will find this useful :)
19 Comments
adrian
1/13/2021 03:10:40 pm
I should probably use it before suggesting changes, but having been tempted to do something like this to enhance the display of arduino plotter output (but lacking the skill to do the PC part) I'd consider :
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adrian
1/13/2021 03:22:08 pm
in fact, I think you already have (4) as the 'auto' mode - I had thought the data was embedded in the json
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Alex Spataru
1/13/2021 08:40:16 pm
Hi, some of the features you mentioned are already supported (sort of):
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Eduardo
1/18/2021 01:20:05 pm
As a suggestion, a clear button would be nice, because right now I'm using this solution only for monitor Serial response, because I think the serial monitor from arduino and esp32 a bit ugly.
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Alex Spataru
1/20/2021 07:50:05 am
I've just added a clear console button with the latest commit. The feature will be available in the next release (v1.0.11), thanks for the suggestion!
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Eduardo
1/25/2021 01:32:57 pm
Thanks for taking this suggestion. As I said before, this solution is really good looking and well designed and I hope that the community use it as primary Serial Monitor, because Arduino IDE and VS CODE serial monitor are not that appealing.
César
1/30/2021 09:21:49 am
Hola Alex: antes de nada enhorabuena por este maravilloso proyecto. Es genial. Mis futuros equipos que participen en Cansat España seguro que lo usarán y sacarán buen provecho de ello. La verdad es que es muy rápido y fácil generar la interface para el cansat.
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César
2/1/2021 02:46:27 am
Hi Alex: first of all, congratulations on this wonderful project. He is great. My future teams that participate in Cansat Spain will surely use it and take advantage of it. The truth is that it is very fast and easy to generate the interface for the cansat.
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Alex Spataru
2/1/2021 11:38:36 am
Hola César, muchas gracias por el agradecimiento. En cuanto al mapa, Serial Studio requiere la instalación de OpenSSL para mostrar los datos del mapa. El instalador de Windows debería de venir una distribución de las bibliotecas de OpenSSL. Sin embargo no he tenido chance de hacer pruebas extensivas debido a que en general uso macOS o Linux por cuestiones de trabajo.
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Alex Spataru
2/2/2021 12:49:02 pm
Hola de nuevo, la última versión del software soluciona tus problemas con los mapas. El bug report de este problema se encuentra en: https://github.com/Serial-Studio/Serial-Studio/issues/19
César
2/2/2021 01:13:58 pm
Gracias de nuevo Alex. Quedó resuelto el problema con los mapas en la última versión (1.0.13). En los próximos días testearé el giroscopio y acelerómetro y si todo va bien, es la aplicación perfecta para los cansats.
Erkko
1/31/2021 11:52:05 pm
Is it possible to send data in fixed width "chunks" with each frame?
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Erkko
2/1/2021 12:23:24 am
Or, many times when you're dealing with IoT stuff, the amount of data you can send is rather limited, or you're trying to minimize transmission time to shut everything down quickly, so you don't want extra stuff in the frame. Every second the transmitter is on eats up your battery.
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Erkko
2/1/2021 12:47:10 am
One use case for the fast data dump is when you have some sensor, like a microphone next to a running motor, and you want to build a system that takes 1 seconds of sound at a reasonable sample rate from the mic every few minutes and collects it for analysis - so you can listen if the bearings are going out or the fan is blocked etc.
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adrian
2/1/2021 01:38:44 am
One way to do this is by escaping, or byte stuffing the stream.You put a framing character in, and if that's ever required as part of the stream data you 'escape' it by sending a 2-byte sequence of some other special character followed by a modified version of the framing character (eg the top bit flipped). Of course, you have to escape the escape character too.
Erkko
2/1/2021 06:11:38 am
Well, in my case it can be that the top byte can never reach 0xFF so there can never be 0xFFFF in the stream. This is because the ADC is actually 12 bits unsigned, so it will never produce that value. If it was signed int, then that would be -1 and that wouldn't work.
Steve Hageman
2/1/2021 08:09:19 am
Wow! You are my hero! :-)
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Mark
2/2/2021 11:32:50 am
Really nicely done! The overall UI design is just beautiful and well thought out.
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Yohan H
2/23/2021 11:33:04 pm
Hi Alex!
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