#!/usr/bin/env python3 ''' Program to manipulate a GPIO pin of the Raspberry Pi 4. Should work on other 40-pin Pi models. Provides PWM output on GPIO18 (physical pin 12) and can change the duty cycle and frequency of output. Percent limit set to 100%. Frequency default set at 50 Hz with the limit set to 500 Hz as the signal has a lot of jitter above that. Oct 2019, Bonedog32. ''' import RPi.GPIO as GPIO # a Python module to control the GPIO interface. import tkinter as tk GPIO.setwarnings(False) # Turn off "pin in use" warnings GPIO.setmode(GPIO.BOARD) # use physical pin numbering GPIO.setup(12, GPIO.OUT) # Set GPIO18 to output pin. p = GPIO.PWM(12, 50) # physical pin 12 (GPIO18) at 50 Hz class MyApp: # "Constructor" def __init__(self,parent): self.myParent = parent # set title self.myParent.title("GPIO PWM") # set window title self.myParent.geometry('320x76') # set window size # Make topmost container with everything else inside self.myContainer1 = tk.Frame(parent) # topmost frame: myContainer1 self.myContainer1.grid() #------ constants for controlling layout ------ button_width = 10 button_padx = "2m" # 'm' = millimeters button_pady = "2m" # -------------- end constants ---------------- # two more containers, left one for menu buttons, right one for data, horizontal layout. # left frame inside myContainer1 self.left_frame = tk.Frame(self.myContainer1, background="tan", borderwidth=2, relief=tk.RIDGE, height=76, width=50) self.left_frame.grid(row=0) # right frame inside myContainer1 self.right_frame = tk.Frame(self.myContainer1, background="gray", borderwidth=2, relief=tk.RIDGE, height=76, width=250) self.right_frame.grid(row=0, column=1) # add buttons for menu selection to left_frame self.button1 = tk.Button(self.left_frame, text='Activate', command=self.set_percent) self.button1.configure(activebackground="green",background = "lightgreen", width=button_width, padx=button_padx, pady=button_pady) self.button4 = tk.Button(self.left_frame, text='Quit', command=self.button4Click) self.button4.configure(activebackground = "red", background = "pink", width=button_width, padx=button_padx, pady=button_pady) self.button1.grid() self.button4.grid() def button4Click(self): #p.ChangeDutyCycle(0) # set output to zero (optional) p.stop() # Stop PWM mode on Pi 4 self.myParent.destroy() # destroy entire window def NewFrame(self, color): # new 'right_frame' inside myContainer1. Use 'color' for background self.right_frame.destroy() # delete old frame before creating new one self.right_frame = tk.Frame(self.myContainer1, background=color, borderwidth=2, relief=tk.RIDGE, height=120, width=250, padx='5m') self.right_frame.grid(row=0, column=1) def set_percent(self): self.button1.configure(activebackground="green",background = "green") color = '#9f3' # color input to NewFrame() self.NewFrame(color) # call function to build new frame # zero variables self.dc = 0 p.start(self.dc) self.freq = 50 # set variable label to accept floats self.percent_label_text = tk.DoubleVar(self.right_frame) # assign to right_frame self.percent_label_text.set(self.dc) # assign duty cycle field to label self.freq_label_text = tk.DoubleVar(self.right_frame) # assign to right frame self.freq_label_text.set(self.freq) # assign frequency field to label #place label in right_frame self.percent_label = tk.Label(self.right_frame, textvariable=self.percent_label_text, bg=color) # label formats assigned to right_frame self.label = tk.Label(self.right_frame, text="Set PWM Percent/Frequency", bg=color) self.label1 = tk.Label(self.right_frame, text="Enter %:", bg=color) self.label3 = tk.Label(self.right_frame, text="Enter freq: ",bg=color) # setup entry fields # Place these widgets in desired order of 'event.widget.tk_focusNext().focus()' self.percent_entry = tk.Text(self.right_frame, width=10, height=1) # create text entry box self.percent_entry.focus_set() # place cursor in text box self.percent_entry.bind("", self.calc_percent) # execute function self.percent_entry.bind("", FocusNextWindow) # to Freq entry box self.freq_entry = tk.Text(self.right_frame, width=10, height=1) self.freq_entry.bind("", self.calc_percent) # execute function self.freq_entry.bind("", FocusNextWindow) # to Calculate button # SCREEN LAYOUT AND POSITIONING # position various widgets. 'sticky' used to expand contents to fill complete cell width. self.label.grid(row=0, columnspan=2) # Main title self.label1.grid(row=1) # Enter percent prompt self.percent_entry.grid(row=1, column=1, sticky=tk.W+tk.E) # entry box for percent value self.label3.grid(row=3) # enter freq prompt self.freq_entry.grid(row=3, column=1, sticky=tk.W+tk.E) # entry box for freq value def calc_percent(self, event=None): # 1.0 = start at first char; tk.END = all way to end; strip() = remove newline & spaces. pct_text = self.percent_entry.get(1.0, tk.END).strip() fq_text = self.freq_entry.get(1.0, tk.END).strip() if len(pct_text) > 0: # don't act if blank entry dc = float(pct_text) if dc <= 100: # limit to 100% p.ChangeDutyCycle(dc) if len(fq_text) > 0: # don't act if blank entry fq = float(fq_text) if fq <= 500: # gets unstable above 500 Hz p.ChangeFrequency(fq) self.percent_entry.delete(1.0, tk.END) # clear percent input box self.freq_entry.delete(1.0, tk.END) # clear frequency text box self.percent_entry.focus_set() # place cursor in percent text box def FocusNextWindow(event): # move cursor to next entry field event.widget.tk_focusNext().focus() return("break") def centerWindow(): # open the Tkinter window in center of screen w = 320 # width for the Tk root h = 76 # height for the Tk root # get screen width and height ws = root.winfo_screenwidth() # screen width/2 (for dual screens) hs = root.winfo_screenheight() # height of the screen # calculate x and y coordinates for the Tk root window x = ((ws/2) - (w/2)) y = (hs/2) - (h/2) # set the dimensions of the screen # and where it is placed root.geometry('%dx%d+%d+%d' % (w, h, x, y)) # main program loop ------------------------ root = tk.Tk() centerWindow() myapp = MyApp(root) root.mainloop()