from typing import Optional

import numpy as np
import serial
from flojoy import OrderedPair, SerialDevice, flojoy


@flojoy(deps={"pyserial": "3.5"})
def SERIAL_SINGLE_MEASUREMENT(
    device: SerialDevice,
    default: Optional[OrderedPair] = None,
    baudrate: int = 9600,
) -> OrderedPair:
    """The SERIAL_SINGLE_MEASUREMENT node takes a single reading of data from an Arduino or a similar serial device.

    Parameters
    ----------
    baudrate : int
        Baud rate for the serial communication.
    comport : string
        Defines the communication port on which the serial device is connected.

    Returns
    -------
    OrderedPair
        the y axis contains the reading
    """

    set = serial.Serial(device.port, timeout=1, baudrate=baudrate)
    s = ""
    while s == "":
        s = set.readline().decode()

    reading = s[:-2].split(",")
    reading = np.array(reading)  # Create an array
    reading = reading.astype("float64")  # Convert the array to float
    x = np.arange(0, reading.size)  # Create a second array

    return OrderedPair(x=x, y=reading)

Example

In this example, we use the SERIAL_SINGLE_MEASUREMENT node to extract some measurements received from an Arduino microcontroller and visualize the output.

First, you need to connect the Arduino to your computer. Then, you’ll need to upload an Arduino script to your board to define its behavior (with the Arduino IDE software). When your Arduino sends data to the serial monitor of the Arduino IDE, you can start using the SERIAL_SINGLE_MEASUREMENT node. After placing the node on Flojoy, you must specify the communication port to which the Arduino is connected. This port is found in the Arduino IDE software under Tools/Port.

The SERIAL_SINGLE_MEASUREMENT node receives data through serial communication with the Arduino, and stores the measured values in a table called reading. The Arduino then prints new values on the serial console for each loop. The SERIAL_SINGLE_MEASUREMENT node extracts a measurement (which can contain single or multiple values, as seen in the output).

The TABLE node displays all values stored in the single measurement.

Remarks about the Arduino code:

This example works with the arduino_example.ino Arduino code (see Appendix).

The last line that the Arduino should return, is the data with a new line at the end (i.e. println()).

For example:

print(reading0)
print(",")
println(reading1)

The SERIAL_SINGLE_MEASUREMENT node receives data from the Arduino serial console as a string and splits it using ”,” as a separator. It then returns the values measured in a list called reading.

Update the Single Measurement with a Loop:

To update the values received from the Arduino, use the LOOP node to create a loop around the SERIAL_SINGLE_MEASUREMENT and TABLE nodes.

The loop allows the user to update measurements, but only the last measurement will be saved and displayed.

To record all the measurements for a given period, use the SERIAL_TIMESERIES node.