Software PWM loop challenge

[simplesi]

I've got this running in a loop

Code: Select all

if (motor != 0):
            GPIO.output(13, 1)
            print "on",motor
            time.sleep(motor/1000.0)
            GPIO.output(13, 0)
            print "off"
            time.sleep((100.0-motor)/1000.0)

which is controlling a little motor fine but I need to extend it to handle 6 outputs instead of just the 1
so I've changed motor to motor[0,0,0,0,0,0] and I've another list that indexes the pins - pinarray[11,12,13,15,16,18]

I'm looking for clever code to convert the single instance above to handle the 6 values in motor[]

Obviously it needs to switch each pin on for the correct amount of time and each one off for (near enough) the correct amount of time

Anyone got a super algorithim ?
regards
Simon
PS its for my Scratch GPIO Handler

[Grumpy Mike]

Look here:-
https://projects.drogon.net/software-pw ... pberry-pi/

[simplesi]

@grump mike - Thanks very much - it'd mean I'd have to switch from @croston's GPIO lib but looks like the code for the job.

Simon

[simplesi]

Since I can't get wiringpi to work in python I've come up with this little bit of code to handle 2 pwm outputs (which is all I need to control 2 dc motors)

Code: Select all

motorA = 0;
motorB = 0;
motor_timing = array('i',[0,0,100])
motor_order = array('i',[0,1])
while True:
#
#other code to get integer values for motorA and motorB
#
        if ((motorA > 0) or (motorB > 0)):
            if (motorA > motorB):
                motor_order[0]=0
                motor_order[1]=1
                #time before motorB goes off
                motor_timing[0]=motorB
                motor_timing[1]=motorA-motorB
                motor_timing[2]=100-motorA
            else:
                motor_order[0]=1
                motor_order[1]=0
                #time before motorA goes off
                motor_timing[0]=motorA
                motor_timing[1]=motorB-motorA
                motor_timing[2]=100-motorB


            #print 't0 t1 t2', motor_timing[0], motor_timing[1] , motor_timing[2]                
            #print 'pin: ' , GPIO_PINS[0]
            GPIO.output(GPIO_PINS[motor_order[0]], 1)
            if (motor_timing[0] > 0 ):
                GPIO.output(GPIO_PINS[motor_order[1]], 1)
            time.sleep(motor_timing[0]/10000.0)
            GPIO.output(GPIO_PIN_OUTPUT[motor_order[1]], 0)
            time.sleep(motor_timing[1]/10000.0)
            GPIO.output(GPIO_PIN_OUTPUT[motor_order[0]], 0)
            time.sleep(motor_timing[2]/10000.0)      

The code might be of use to others
(And of course it could always be improved)

Simon

[texy]

Whats the problem with installing wiringpi? Using the 'pip' method worked for me on a fresh raspbian install recently.

Texy

[simplesi]

Whats the problem with installing wiringpi?

No problem in installing wiringpi

Great problem in getting it to ackle in Python
(Gordon doesn't supply/support wiringpi in Python )

What's "pip" ?

Simon

[alexeames]

I did it on a fresh raspbian yesterday...

Code: Select all

sudo apt-get update

sudo apt-get install python-dev python-pip
sudo pip install wiringpi

pip handles the compile and install for you, python-dev is a required library.

I haven't tried to use wiringpi for python yet mind, but it installed ok.

[texy]

Wiringpi works fine for me - as I,m sure i,ve said before, it seems to be the only python compatible method of using hardware pwm, so is driving my
Nokia Pi LCD's backlight correctly.

Texy

[simplesi]

I haven't tried to use wiringpi for python yet mind, but it installed ok

Mine installed Ok as well (different method mind) - just doesn't work

I'm not going to spend anymore time on trying to get wiringpi to work as with my simple PWM method here - I've got the outcome I need to control 2 motors

Simon