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azhar_multan
Joined: 24 Aug 2012 Posts: 1 Location: Lahore
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Help! Inverted PWM in 16F73 |
Posted: Sat Mar 08, 2014 8:53 pm |
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Hello,
Is it possible to get inverted PWM in 16F73 ? Actually I need both inverted and non inverted outputs. So ideal solution for me is to have one module operating in normal mode and the second one in inverted mode.
Regards |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19368
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Posted: Sun Mar 09, 2014 1:07 am |
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Read the data sheet.
No.
To have inverted outputs available requires a chip with a more sophisticated module like the ECCP. Why on earth use such an old chip though?. It is not flagged as obsolete yet, but cannot be far from being so. In general newer chips offer extra features like the ECCP, and are cheaper as well. |
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temtronic
Joined: 01 Jul 2010 Posts: 9174 Location: Greensville,Ontario
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Posted: Sun Mar 09, 2014 5:47 am |
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As MR. T points old, 'ancient' PIC.....however if you're stuck using it, simply add an inverter to the PWM output pin.
Depending on the overall speed of the project, you probably will not notice any effect of the small propagation delay of the inverter.
Another option, again if a small delay is OK, is to select another I/O pin and invert it's output based upon the PWM signal.This also could work for you , though there will be a greater delay due to the program reading,deciding, setting I/O bits.
For low frequency PWM(<20KHz) or non critical loads( lights,audio) either method will work.
I do suggest that you use a new PIC though as Mr. T. says, if possible!
hth
jay |
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asmboy
Joined: 20 Nov 2007 Posts: 2128 Location: albany ny
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Posted: Sun Mar 09, 2014 4:18 pm |
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Quote: |
both inverted and non inverted outputs
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but be aware that if you stick with antique parts
that the inverter approach suggested,
can make "shoot-through" trouble at higher frequencies,
especially if you are using the two signals to drive a synchronous
buck converter or similar totem-pole mosfet pair,
due to asymmetric switch time delays,
quite possible in the LOAD side of your circuit.
Not knowing the frequency or your circuit- i
can't comment further.
using a more suitable PIC is the real answer here. |
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