Arduino Driver guide

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Revision as of 20:56, 24 May 2022 by Afischer (talk | contribs) (Afischer moved page Arduino Device Class guide to Arduino Driver guide: renaming)
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Using existing Device Classes

Already existing Arduino Device Classes, e.g. implemented as Logger or Switch, can be used after configuring the Arduino.

  1. Install the ArduinoIDE
  2. For every Device Class, there exists one ".ino" file which can be found in the corresponding Device Class folder
  3. Double-click the ".ino" file and the ArduinoIDE will open
  4. Configure your ArduinoIDE by setting the Arduino type (e.g. nano, uno, or mega) and the COM port
  5. Upload the ".ino" file to the Arduino
  6. Now your Arduino knows how to handle the commands send by the SweepMe! Device Class

Creating an own Device Class for Arduino

Arduino can easily be combined with SweepMe! However, there are some guidelines which make the implementation much easier:

  1. Try to sends a text during the setup() routine of the Arduino, so that SweepMe! knows that sending commands can be done from now on.
  2. The Arduino can send text via its function println() which uses a LineFeed character as terminator ("\n"). Thus, the Arduino should also expect to receive messages ending with a LineFeed ("\n") so that the write and read terminators are identical. The standard terminator of SweepMe! is a LineFeed ("\n") so that you do not have to set it.
  3. If the Arduino sends a message back after receiving a command, do not send more than one line. Otherwise, one has to read out the COM port multiple times in the SweepMe! Device Class
  4. Try to have a constant length or format of the return message, so that reading out the string is less errorneous
  5. Try to make every parameter adjustable by a single command, e.g. "Pixel = 03", "Voltage = 0.05", or "Frequency = 400". That way, multiple items of the sequencer can communicate with the Arduino and multiple parameters can be swept.
  6. Use the standard baudrate of 9600 so that other Arduino Device Classes can easily be copied and modified.
  7. After finishing your Device Class, put your ino file as uploaded to the Arduino into the folder of the Device Class. Give the ino file exactly the same name as used for the folder to allow for easy manipulation using the Arduino IDE.

Example Device Class

Arduinos are typically implemented as Switch if you rather set some values or as Logger if your rather read some value. The following code shows a Device Class which can set and read a value.

from EmptyDeviceClass import EmptyDevice  # Loading the EmptyDevice Class

class Device(EmptyDevice):            # Creating a new Device Class by inheriting from EmptyDevice
    def __init__(self):               # The python class object need to be initialized
        EmptyDevice.__init__(self)     # Finally, the initialization of EmptyDevice has to be done

        self.variables = ["A variable to read out"]
        self.units = ["The unit of the variable"]
        self.plottype = [True]     # set to False if the variable is a string and cannot be plotted
        self.savetype = [True]     # set to False if there is no need to save the variable to the data file

        self.port_manager = True            # using the port manager works seamlessly
        self.port_types = ["COM"]           # Arduinos are always listed as COM ports = {
                                "timeout" : 2, # set timeout of the COM port to 2 seconds, which is necessary to prevent timeout error during initialization

    def initialize(self):              # readout the COM port to know that the Arduino is ready to receive commands
        # It will read out the "Arduino initialized" that the Arduino sends in the .ino file below

    def apply(self):
        print self.value              # self.value is always the actual value to be set, print to see exact format

        self.port.write("Voltage=" + str(self.value)) # here we send the new command to the Arduino
    def reach(self):              # read out the COM port to know that the Arduino has finished setting the parameter. Only use it if the Arduino sends a response.

    def measure(self):
        self.port.write("Read?")         # send some command to request a reading of parameters, for example "Read?" or any other command. Only use it if the Arduino can read parameters

    def call(self)
        self.answer =              # read out the COM port
        return [float(self.answer)]                 # return the answer to SweepMe!. Do not forget to transform the string to any format as needed e.g. float or integer

Example Arduino .ino file

The following code shows you an example how to implement the above guidelines into an Arduino ino file. It has to be adapted to your needs.

// define some variables
unsigned int variable1; 
String command; // the variable command 

// define functions which you need later
void myFunction() 

void setup()
   // configure your pins here   

   Serial.begin(9600);  // set Arduino to baudrate 9600
   // Serial.setTimeout(1000); // change timeout if necessary, default is 1000 ms
   Serial.println("Arduino initialized"); // send some text to let SweepMe! know that the Arduino has finished the setup() function

void loop ()

  // check whether some command has been received at the COM port
  if (Serial.available()) {
    command = Serial.readStringUntil('\n'); // make sure you have '\n', "\n" does not work

    if (command == "Read?") {

        // sending back the answer.
        Serial.print("some text");
        Serial.print("some further text");
        Serial.println(""); // you can send multiple times using print, but only send println to reply with a single message after each command

    // if the command starts with some special text you can 
    else if (command == "Voltage?") {

       // use some functions to get the parameter 'voltage' and return it
       voltage = some_function_to_retrieve_the_voltage_value();
       Serial.println(voltage); // here we send the value, the command 'println' adds a Line Feed character ('\n') to each message automatically 

    // if the command starts with some special text you can 
    else if (command.startsWith("Voltage=")) {

       // split the value from the command here and change the parameter accordingly
       float set_voltage = command.substring(command.indexOf('=')+1).toFloat();
       my_voltage_function(set_voltage); // here you need to run any function that changes the voltage 
       Serial.println("Voltage=..."); // reply to let SweepMe! know that the parameter is changed.

    else if (command == "Frequency?") {
       // split the value from the command here and change the parameter accordingly
       frequency = some_function_to_retrieve_the_frequency_value();
       Serial.println(frequency); // reply to let SweepMe! know that the parameter is changed

    else if (command.startsWith("Frequency=")) {
       // split the value from the command here and change the parameter accordingly
       int set_frequency = command.substring(command.indexOf('=')+1).toInt();
       my_frequency_function(set_frequency); // here you need to run any function that changes the voltage 
       Serial.println("Frequency=..."); // reply to let SweepMe! know that the parameter is changed