frontEnd.py File Reference

PC Script for Lab 0x0FF. More...

Functions
def	frontEnd.kb_cb (key)
	Callback method based on keyboard inputs. More...
def	frontEnd.sendChar (lastKey)
	Method for sending characters via serial to Nucleo. More...
def	frontEnd.clearFiles (fileNames)
	Method for deleting files. More...
def	frontEnd.writeCSV (fromNucleo, csvFileName)
	Method for writing a .csv file. More...
def	frontEnd.createPlot (csvFileName, pngFileName, figureCaption, posCol, speedCol, tRef, speedRef, posRef, Kp, Ki, J)
	Method for creating a plot. More...
def	frontEnd.sampleCSV (referenceCSV, modified, controllerPeriod)
	Method for resampling reference data at lower resolution. More...

Variables
list	frontEnd.t = []
	Reference time list.
list	frontEnd.omega = []
	Reference speed list.
list	frontEnd.theta = []
	Reference position list.
	frontEnd.ser = serial.Serial(port='COM5',baudrate=115273,timeout=1)
	Serial port definition. More...
list	frontEnd.callbackKeys = ["s","g","z","p","d","v","x","o","f","w","r"]
	Define callback keys. More...
	frontEnd.callback
	callback for keys
	frontEnd.lastKey = None
	Initial value of last key released. More...
bool	frontEnd.userPrompt = True
	Boolean variable for displaying UI options. More...
bool	frontEnd.debugFlag = False
	Debugging flag for print statements in Spyder.
int	frontEnd.Kp = 0
	Kp value sent from UI.
int	frontEnd.Ki = 0
	Ki value sent from UI.
int	frontEnd.J1 = 0
	J value for encoder 1 sent from UI.
int	frontEnd.J2 = 0
	J value for encoder 2 sent from UI.
	frontEnd.fromNucleo = ser.readline().decode('ascii')
	Most recent line read from serial communciation between the PC and the Nucleo.
	frontEnd.currentFromNucleo = fromNucleo
	Non empty line from Nucleo serial communication.
	frontEnd.metrics = currentFromNucleo[1:]
	CSV of Kp, Ki, and J values.

Detailed Description

PC Script for Lab 0x0FF.

This file serves to run the PC (or front end) side of operations for our lab. From this script, keystroke commands are sent to the Nucleo, data is processed into a .csv file, and data is plotted to produce a .png file

See source code here: https://bitbucket.org/ryanmclaug/me_305/src/master/Lab0xFF/frontEnd.py

Example output .csv file here: https://bitbucket.org/ryanmclaug/me_305/src/master/Lab0xFF/outputDataExample.csv

Shown above is an example output plot from frontEnd.py

Author

Ryan McLaughlin

Date

Originally created on 02/18/21
Last modified on 03/17/21

Function Documentation

clearFiles()

def frontEnd.clearFiles

(

fileNames

)

Method for deleting files.

Since the csv writer is set to append to a certain file, the file to be written to must be removed each time the PC collects new data. If it was desired, this could be replaced by a method to rename the next file to write to a new file each time. For this, the os module is used.

Parameters

fileNames

is a list of strings containing the various files written each time the frontEnd is run

createPlot()

def frontEnd.createPlot	(		csvFileName,
			pngFileName,
			figureCaption,
			posCol,
			speedCol,
			tRef,
			speedRef,
			posRef,
			Kp,
			Ki,
			J
	)

Method for creating a plot.

This method utilizes the matplotlib module to plot data from a .csv file created earlier. The .csv file is used for plotting in conjunction with the numpy module, and then the plot is saved to a .png file in the working directory.

Parameters

csvFileName	is the specified file name of the output .csv file
pngFileName	is the specified file name of the output .png file
figureCaption	The desired caption for the plot
posCol	Column in output csv file containing speed data for the appropriate encoder
speedCol	Column in output csv file containing position data for the appropriate encoder
tRef	Refrence time data
speedRef	Reference speed data
posRef	Reference position data
Kp	Gain value for speed feedback
Ki	Gain value for position feedback
J	Performance metric

kb_cb()

def frontEnd.kb_cb

(

key

)

Callback method based on keyboard inputs.

In order to use the keyboard to set certain tasks into motion, a callback is used, along with the keyboard module for python. Only an "s" or "g" will be able to trigger the callback.

Parameters

key	is the key released by the user

sampleCSV()

def frontEnd.sampleCSV	(		referenceCSV,
			modified,
			controllerPeriod
	)

Method for resampling reference data at lower resolution.

This method uses the numpy library to resample a refrence data set for reference tracking. Instead of loading in every line of a given csv file, an increasing number of rows are skipped over, and a single line is read each time through the loop, creating a lower resolution data set (so that memory issues do not occur on the Nucleo).

Parameters

referenceCSV	Original file name
modified	Modified file name
controllerPeriod	Needed to determine at what rate to resample

Returns

Lists for time, speed, and position that can be used for plotting

sendChar()

def frontEnd.sendChar

(

lastKey

)

Method for sending characters via serial to Nucleo.

sendChar writes characters from the PC to the Nucleo by encoding as ascii characters, then decoding

Parameters

lastKey

is the last key released on the keyboard.

writeCSV()

def frontEnd.writeCSV	(		fromNucleo,
			csvFileName
	)

Method for writing a .csv file.

As data is being transferred from the Nucleo to the PC, we want to append this data to a .csv file for later use/analyis. Initially, the string is already in a csv type format, but to write it to a csv file, we need to strip the string of line endings, split it on commas, convert to type float, then append a new row to the .csv file.

Parameters

fromNucleo	is the string read from uart for a given iteration
csvFileName	is the specified file name of the output .csv file

Variable Documentation

callbackKeys

list frontEnd.callbackKeys = ["s","g","z","p","d","v","x","o","f","w","r"]

Define callback keys.

Using keyboard.on_release_key with "s" and "g" to implement callbacks from key presses

lastKey

frontEnd.lastKey = None

Initial value of last key released.

Setup such that key press callback is only checked if lastKey is not None.

ser

frontEnd.ser = serial.Serial(port='COM5',baudrate=115273,timeout=1)

Serial port definition.

Need to specify the port to use for serial communication, as well as a baud rate

userPrompt

bool frontEnd.userPrompt = True

Boolean variable for displaying UI options.

Intitially set to True, the user prompt message is displayed following any key press to inform the user of possible options