I asked Sebi to provide some option to visualise forces read by those cells and gave him a brief idea what I had on my mind thinking that it will entertain him for some time. Meanwhile I took on my the Monkey-business job of the cable crimping.
before 
after
Not too shabby, huh? 🙂
Anyway, before I’ve been able to finish my crimping task – Sebi reported his part done!
What you see on the picture above is simplified graphical interpretation of our testing rig with forces pulling in a corner. I’ve asked Sebi to tell you what’s going on in his words.
I took a picture of whole setup.
And asked Sebi to give away his Python and Arduino code (Python first).
import pygame
import math
from pygame.time import Clock
import serial
def map(value = float, fromStart = float, fromEnd = float, toStart = float, toEnd = float):
return toStart + (toEnd - toStart) * ((value - fromStart) / (fromEnd - fromStart))
# specifications
ARROW_HEAD_SCALE = 1
ARROW_LINE_SCALE = 1
TEXT_SCALE = 1
OUTPUT_DECIMALS = 4
BACKGROUND_COLOUR = (255, 255, 255)
ARROW_HEAD_COLOUR = (0,0,0)
ARROW_LINE_COLOUR = (0,0,0)
BODY_COLOUR = (0,0,0)
TEXT_COLOUR = (0,0,0)
TEXT_FONT = "arial"
pygame.init()
# of specific dimension..e(X, Y).
MainWindow = pygame.display.set_mode((0, 0),
pygame.RESIZABLE, pygame.FULLSCREEN)
pygame.font.init() # you have to call this at the start,
# if you want to use this module.
# set the pygame window name
pygame.display.set_caption('BPI')
def arrow(screen, lcolour, tricolour, start, end, trirad, thickness=2):
rad = math.pi/180
pygame.draw.line(screen, lcolour, start, end, thickness)
rotation = (math.atan2(start[1] - end[1], end[0] - start[0])) + math.pi/2
pygame.draw.polygon(screen, tricolour, ((end[0] + trirad * math.sin(rotation),
end[1] + trirad * math.cos(rotation)),
(end[0] + trirad * math.sin(rotation - 120*rad),
end[1] + trirad * math.cos(rotation - 120*rad)),
(end[0] + trirad * math.sin(rotation + 120*rad),
end[1] + trirad * math.cos(rotation + 120*rad))))
setattr(pygame.draw, 'arrow', arrow)
sensorOutput = 8 * [0.5]
serialPort = serial.Serial(port = "/dev/ttyACM0", baudrate=9600,
bytesize=8, timeout=2, stopbits=serial.STOPBITS_ONE)
serialString = "" # Used to hold data coming over UART
# infinite loop
while True:
if(serialPort.in_waiting > 0):
# Read data out of the buffer until a carraige return / new line is found
serialString = serialPort.readline()
# Print the contents of the serial data
serialString = serialString[:-2].decode('Ascii')
rawOutput = serialString.split(",")
print(rawOutput)
if len(rawOutput) == 2: # and isinstance(rawOutput[0], float) and isinstance(rawOutput[1],float)
sensorOutput[1] = map(float(rawOutput[0]), 0, 2000, 0, 1)
sensorOutput[2] = map(float(rawOutput[1]), 0, 2000, 0, 1)
windowWidth, windowHeight = pygame.display.get_surface().get_size()
MainWindow.fill(BACKGROUND_COLOUR)
pygame.draw.rect(MainWindow, BODY_COLOUR, (windowWidth/3, windowHeight/3, windowWidth/3, windowHeight/3))
# top left
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/3, windowHeight/2.4), (windowWidth/3-windowWidth/3*sensorOutput[0], windowHeight/2.4), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# top left centre
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/2.4, windowHeight/3), (windowWidth/2.4, windowHeight/3-windowHeight/3*sensorOutput[1]), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# top right centre
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/12*7, windowHeight/3), (windowWidth/12*7, windowHeight/3-windowHeight/3*sensorOutput[2]), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# top right
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/1.5-1, windowHeight/2.4), (windowWidth/1.5+windowWidth/3*sensorOutput[6], windowHeight/2.4), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# bottom left
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/3, windowHeight/12*7), (windowWidth/3-windowWidth/3*sensorOutput[4], windowHeight/12*7), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# bottom left centre
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/2.4, windowHeight/1.5-1), (windowWidth/2.4, windowHeight/1.5+windowHeight/3*sensorOutput[5]), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# bottom right centre
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/12*7, windowHeight/1.5-1), (windowWidth/12*7, windowHeight/1.5+windowHeight/3*sensorOutput[3]), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
# bottom right
pygame.draw.arrow(MainWindow, ARROW_LINE_COLOUR, ARROW_HEAD_COLOUR, (windowWidth/1.5-1, windowHeight/12*7), (windowWidth/1.5+windowWidth/3*sensorOutput[7], windowHeight/12*7), round(windowWidth/24)*ARROW_HEAD_SCALE, round(windowWidth/24)*ARROW_LINE_SCALE)
textFont = pygame.font.SysFont(TEXT_FONT, round((windowWidth/26)+(windowHeight/26)/2*TEXT_SCALE))
topLeft = textFont.render(str(round(sensorOutput[0],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
topLeftCentre = textFont.render(str(round(sensorOutput[1],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
topRightCentre = textFont.render(str(round(sensorOutput[2],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
topRight = textFont.render(str(round(sensorOutput[3],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
bottomLeft = textFont.render(str(round(sensorOutput[4],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
bottomLeftCentre = textFont.render(str(round(sensorOutput[5],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
bottomRightCentre = textFont.render(str(round(sensorOutput[6],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
bottomRight = textFont.render(str(round(sensorOutput[7],OUTPUT_DECIMALS)), True, TEXT_COLOUR)
MainWindow.blit(topLeft, dest=(0, windowHeight/3-topLeft.get_height()))
MainWindow.blit(topLeftCentre, dest = (windowWidth/3-topLeftCentre.get_width(), 0))
MainWindow.blit(topRightCentre, dest = (windowWidth/1.5, 0))
MainWindow.blit(topRight, dest=(windowWidth-topRight.get_width(), windowHeight/3-topRight.get_height()))
MainWindow.blit(bottomLeft, dest=(0, windowHeight/1.5))
MainWindow.blit(bottomLeftCentre, dest=(windowWidth/3-bottomLeftCentre.get_width(), windowHeight-bottomLeftCentre.get_height()))
MainWindow.blit(bottomRightCentre, dest=(windowWidth/1.5, windowHeight-bottomRightCentre.get_height()))
MainWindow.blit(bottomRight, dest=(windowWidth-bottomRight.get_width(), windowHeight/1.5))
pygame.display.update()
Clock().tick_busy_loop(20)
Now Arduino
#include "HX711.h"
#define calibration_factor -21600 //This value is obtained using the SparkFun_HX711_Calibration sketch
#define LOADCELL_DOUT_PIN 3
#define LOADCELL_SCK_PIN 2
HX711 scale1;
HX711 scale2;
void setup() {
Serial.begin(9600);
Serial.println("HX711 scale demo");
scale1.begin(3, 2);
scale1.set_scale(calibration_factor); //This value is obtained by using the SparkFun_HX711_Calibration sketch
scale1.tare(); //Assuming there is no weight on the scale at start up, reset the scale to 0
scale2.begin(5, 4);
scale2.set_scale(calibration_factor); //This value is obtained by using the SparkFun_HX711_Calibration sketch
scale2.tare(); //Assuming there is no weight on the scale at start up, reset the scale to 0
Serial.println("Readings:");
}
void loop() {
String full = String(scale1.get_units()*10)+", "+String(scale2.get_units()*10);
Serial.println(full);
delay(100);
}
Pretty nice, isn’t it? As always, let us know what you think about it 😉
I feel like I’m looking at a piece of modern art and a musical score. Go, team BBBlimp!
Sent from iPhone by “either” Robin or Serge
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