RC car improvements up to June 2019 - and a future possibility?

Car number 2 works with the software on SD card #3, but the problem is that it takes off too fast and needs a lot more room than I have to fully test it. It also doesn't respond very quickly to the tablet.

I'll give it a go with SD card #7, which has the AP built in and see if that is any better.

- 2019-06-13 Car number 2 with R-Pi3W and Card#7 out on the road, it works aside from the fact that left and right are wrong way around, just not very fast to respond. Is it worth doing a video showing it?
- How can I improve response times?


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Because of the things that I have found out about pwm for driving the RC airplane servo's I might try and make the forward/back work using pwm with every press of the 'forward' button adding 5% to the pwm pulsewidth.

At the moment struggling to get basic pwm operation working in the program instead of go/stop.

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9/9/2019
I did get this working.  One of the things about PWM is that driving Remote Control Servos
uses PWM of about 1.5% to 2.5% ( these are just approx figures from my mind, check elsewhere for actual limits) To drive the car motors I noticed that it didn't do anything at 5% PWM, so I made it increase in steps of 15% and this worked fine. Another challenge was getting the feedback to display in the HTML the figure of the PWM value.

Here is the python code for the car: [some comments removed]

from flask import Flask, render_template

# This gives us control of the Raspberry Pi's pins.
import RPi.GPIO as GPIO
import time

# Tell it which pin number we'll  be using to refer to the GPIO pins.
# We will use the physical pin ordering. Set initial state of pins
GPIO.setmode(GPIO.BOARD)

MotorFwd = 12
MotorBack = 16
MotorLeft = 19
MotorRight = 23
GPIO.setup(MotorFwd, GPIO.OUT)
GPIO.setup(MotorBack, GPIO.OUT)
GPIO.setup(MotorLeft, GPIO.OUT)
GPIO.setup(MotorRight, GPIO.OUT)

# PWM pin
u_d_pin_no = 18
GPIO.setup(u_d_pin_no, GPIO.OUT)


frequency_hertz = 50
pwm = GPIO.PWM(u_d_pin_no, frequency_hertz)

PWM_Stop = 0
PWM_value = 0
PWM_increment = 3
# becomes 15 after calculations

# total number of milliseconds in a a cycle.  Given this, we will then
# know both how long we want to pulse in this cycle and how long tghe
# cycle itself is.  That is all we need to calculate a duty cycle as
# a percentage.
ms_per_cycle = 1000 / frequency_hertz

# now lets get into Flask

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/motor-stop/')
def on():
    # motor.stop()
    PWM_value = 0
    duty_cycle_percentage = PWM_value
#    print("Duty Cycle[S]: " + str(duty_cycle_percentage))
    pwm.start(duty_cycle_percentage)
    return render_template('index.html')


@app.route('/up_15/')
def up_15():
    global PWM_value
    PWM_value = PWM_value + PWM_increment
    duty_cycle_percentage = PWM_value * 100 / ms_per_cycle
#    print("Duty Cycle[F]: " + str(duty_cycle_percentage))
    pwm.start(duty_cycle_percentage)
#    time.sleep(.5)
#    pwm.ChangeDutyCycle(0)
    return render_template('index.html', PWM_PC = duty_cycle_percentage)

@app.route('/down_15/')
def down_15():
    global PWM_value
    if (PWM_value > 0) :
        PWM_value = PWM_value - PWM_increment
        duty_cycle_percentage = PWM_value * 100 / ms_per_cycle
#        print("Duty Cycle[F]: " + str(duty_cycle_percentage))
        pwm.start(duty_cycle_percentage)
#        time.sleep(.5)
#        pwm.ChangeDutyCycle(0)
#    endif
    return render_template('index.html')

@app.route('/motor-left/')
def motorleft():
    GPIO.output(MotorLeft,GPIO.HIGH)
    GPIO.output(MotorRight, GPIO.LOW)
    time.sleep(1)
    GPIO.output(MotorLeft, GPIO.LOW)
    return render_template('index.html')

@app.route('/motor-right/')
def motorright():
    GPIO.output(MotorLeft, GPIO.LOW)
    GPIO.output(MotorRight, GPIO.HIGH)
    time.sleep(1)
    GPIO.output(MotorRight, GPIO.LOW)
    return render_template('index.html')


if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')
# We have shut all our stuff down but we should do a complete
# close on all GPIO stuff.  There's only one copy of real hardware.
# We need to be polite and put it back the way we found it.
    pwm.stop()
    GPIO.cleanup()

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Having done all this I decided to do an R/C boat as it would combine the motor drive and the servo drive. I have given up on this idea because 1] I don't have a boat  2] the little motor that I was going to use didn't work with PWM and 3] I don't have a propellor.