I have been struggling all day with two things in my program(s). This is trying
to use PWM to control a motor.
Problem 1] Incrementing the PWM% by 15% each time the button is pressed.
The error that I am getting is:
File "/home/pi/rc-car/app.py", line 76, in Up_15
PWM_value = PWM_value + PWM_increment
UnboundLocalError: local variable 'PWM_value' referenced before assignment
The code for this is:
@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_value)
where these are initialized:
PWM_Stop = 0
PWM_value = 0
PWM_increment = 15
The second thing that I am trying to do is pass the parameter PWM_Value back to
the HTML and then display it. I see an error there already in a lc 'v'. I
cannot find any help on-line for this.
The particular bit of the HTML that calls the Python is:
<div class="grid-container">
<div class="grid-item"></div>
<div class="grid-item">
<a href="/up_15/" data-toggle="tooltip" title="Forward" class="btn
btn-success">UP +15%</a>
</div>
<div class="grid-item"></div>
In this line following:
<a href="/up_15/" data-toggle="tooltip" title="Forward" class="btn
btn-success">UP +15%</a>
These bits were there in the program that I stole this stuff from:
data-toggle="tooltip" title="Forward" class="btn btn-success" so I don't know
what they do aside from nothing obvious.
Thanks for any help and advice.
Already seen one possibility: The HTML is 'up_15' and the Python it calls is
'Up_15'. But that must work or I wouldn't get the error above.
Peter M.
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