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18F4520 PWM1CON ECCP dead band delay

 
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sunay



Joined: 04 Oct 2011
Posts: 3

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18F4520 PWM1CON ECCP dead band delay
PostPosted: Tue Oct 04, 2011 8:03 am     Reply with quote

Hello,

I've tried to design a microcontroller based half-bridge Mosfet circuit. I 'm using PIC18F4520 that has ECCP module on CCP1. I managed to create PWM signal with this CCP1 module on P1A and out of phase on P1B. Now I just want to make a delay between these PWM signals. I read this site's topics which includes PWM1CON and dead band delay. I used the code as below.

Code:

void set_deadband(int8 deadband)
   {
      #byte PWM1CON = 0x9B
     
      if(deadband > 127)
         deadband = 127;
         PWM1CON = deadband;
   }
 

on its data sheet it says that DELAY=Tosc* PWM1CON

my Tosc =10^-7 and I want 1 us delay so 10^-6/10^-7=PWM1CON

PWM1CON=10 =0x0A



But when I look from the scope with X10 I coulnt catch the delay time :(

Why didnt I see the delay time ? do you have any idea?

with best regards,

sunay
Ttelmah



Joined: 11 Mar 2010
Posts: 19499

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PostPosted: Tue Oct 04, 2011 8:10 am     Reply with quote

PWM1CON, is _not_ at address 0x9B.
That looks like the address for a 16 chip, rather than a 18 chip.

Safest, use:

#byte PWM1CON=getenv("SFR:PWM1CON")

which will automatically put the right address in for you, to avoid this. PWM1CON on your chip is at 0xFB7.....

Best Wishes
sunay



Joined: 04 Oct 2011
Posts: 3

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PostPosted: Tue Oct 04, 2011 10:15 am     Reply with quote

you are absolutely right. I already missed PWM1CON address...

your correction has solved my problem.
#byte PWM1CON=getenv("SFR:PWM1CON")

Thanks for your quick help.


with kind regards,

Sunay
haseeb younus



Joined: 10 Feb 2014
Posts: 1

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PostPosted: Mon Feb 10, 2014 1:30 pm     Reply with quote

Can you plz send me your code on my id [email protected]
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