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PWM control 2 DC Motor

 
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HOHOHAHA



Joined: 13 Apr 2007
Posts: 24

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PWM control 2 DC Motor
PostPosted: Mon Oct 01, 2007 1:50 am     Reply with quote
hi I am trying to implement PWm on my 2 motors ..... motors are connected to a motor driving IC L298, this IC provides 2 different pis to enable 2 motors... I want 2 use CCP1 and CCP2 to control them by just changing the duty cycle ....
Code:

  setup_timer_2(T2_DIV_BY_1, 127, 1);
   setup_ccp1(CCP_PWM);
   set_pwm1_duty(255);
   setup_ccp2(CCP_PWM);
   set_pwm2_duty(255);


later I will use 2 functions to change the duty cycle as required.... will my this piece of code enable CCP1 and CCP2 to run at same frequency ??

I use PIC16f877A and 4.049 ... another thing ... the resolution of PWM is 10 bit .... so it will provide a 5V(0n average ... long span of time) if I set it to 1023.. ? As I need to change the fuse bits of ADC=10 from 8(as default) in case of fuse bit ... do we need to do anything like that here ?

Thanks in advance ...
Ttelmah
Guest
PostPosted: Mon Oct 01, 2007 2:19 am     Reply with quote
You need to do one thing.
Add an 'L' to the '255' values.
The way the set pwm duty function works, is that if it receives a value defines as an 8bit number, it assumes the PWM generator is not using the extra two bits. If it receives a value defined as a 16bit number, it assumes the extra two bits are in use. Adding 'L' to a value below 256, tells the compiler to treat this as a 16bit value, and hand this to the function. Without the 'L', values of 255 and below, will otherwise be assumed to be 8bit, and as shown, the output will simply be permanently 'on'.

Best Wishes
HOHOHAHA



Joined: 13 Apr 2007
Posts: 24

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grt
PostPosted: Mon Oct 01, 2007 3:12 am     Reply with quote
Bro you are great ...thanks a lot !

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