Pic18f - Pwm - Electronic Circuits Projects Diagrams Free

erosennin · 23rd May 2008, 04:17 AM

Hi Everyone,

I've been reading Nigel's tutorial and I now understand how to operate the hardware PWM in the PIC that I wish to use (18F2431).

My question is, once I set all the required registers for hardware PWM, does that continue to use processor cycles like a software pwm? ... I'm not sure I'm being very clear, but what I mean is, if I am reading a keypad and displaying to an LCD as well, will this disrupt the operation of the pwm?

I have a couple of days off before I start my university exam revision for the semester so I thought I'd "restart" the project again... As a result, I'm sure I'll have a few more questions, it might be relatively obvious but I've never used a PIC before... I don't know whether this was a good project to start with, I thought the hardware PWM would simplify my life, but it seems to have complicated it for the moment...

Thank you,
EroSennin.

**3v0** · 23rd May 2008, 07:01 AM

Quote:

does that continue to use processor cycles like a software pwm?

The PWM uses dedicated hardware, you only need the processor to set it up. Once it is setup and running it does not use processor cycles because it is not executing code.

erosennin · 23rd May 2008, 07:31 AM

Excellent, that's what I meant! Thanks.

Now it's time to start meshing together the various aspects...

gramo · 24th May 2008, 02:11 AM

One thing I use extensivly with PWM, is the ability to change the PWM and duty cycle on the fly

The developer of Swordfish released a module called PWM.bas and allows the user to change PWM settings like so;

Code:

 // import PWM module...
Include "PWM.bas"

// local duty variable...
Dim Duty As Byte

// main program...
SetFreq(5000)
While true
   Duty = 0
   Repeat
      SetDutyPercent(Duty)
      Inc(Duty)
      DelayMS(10)
   Until Duty > 100
Wend

Handy! I've used it for control of motor speeds, LED brightness and simple DAC

erosennin · 25th May 2008, 01:24 PM

Hi Gramo,

I saw you reply to a post I had made about Colour Sensing, and clicked around the site you have in your signature.

It looks pretty nice, so I've joined it... I'm about to write a post haha, this doesn't mean ETO that I will ditch you... I promise.

Well basically, for what I want to do, there are 3 PWMs and the user will enter the required duty from 0 to 255, and each controls the brightness of a series of RGB leds...

Thank you for your advice.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Latest
PI controller using PIC18F	elec123	Micro Controllers	17	3rd August 2008 09:45 AM
Error on AN0 PIC18F	mikesmixes777	Micro Controllers	10	8th February 2008 06:28 AM
PIC18F & C Programming	mikesmixes777	Micro Controllers	2	22nd November 2007 09:00 AM
PIC18F & Microchip C18	yngndrw	Micro Controllers	7	24th August 2007 03:25 AM
PIC18F and GOTO $-6	yngndrw	Micro Controllers	12	3rd August 2007 01:09 AM

23rd May 2008, 04:17 AM	(permalink)
erosennin	Pic18f - Pwm Hi Everyone, I've been reading Nigel's tutorial and I now understand how to operate the hardware PWM in the PIC that I wish to use (18F2431). My question is, once I set all the required registers for hardware PWM, does that continue to use processor cycles like a software pwm? ... I'm not sure I'm being very clear, but what I mean is, if I am reading a keypad and displaying to an LCD as well, will this disrupt the operation of the pwm? I have a couple of days off before I start my university exam revision for the semester so I thought I'd "restart" the project again... As a result, I'm sure I'll have a few more questions, it might be relatively obvious but I've never used a PIC before... I don't know whether this was a good project to start with, I thought the hardware PWM would simplify my life, but it seems to have complicated it for the moment... Thank you, EroSennin. __________________ What is a joule per second?

23rd May 2008, 07:31 AM	(permalink)
erosennin	Excellent, that's what I meant! Thanks. Now it's time to start meshing together the various aspects... __________________ What is a joule per second?

24th May 2008, 02:11 AM	(permalink)
gramo	One thing I use extensivly with PWM, is the ability to change the PWM and duty cycle on the fly The developer of Swordfish released a module called PWM.bas and allows the user to change PWM settings like so; Code: // import PWM module... Include "PWM.bas" // local duty variable... Dim Duty As Byte // main program... SetFreq(5000) While true Duty = 0 Repeat SetDutyPercent(Duty) Inc(Duty) DelayMS(10) Until Duty > 100 Wend Handy! I've used it for control of motor speeds, LED brightness and simple DAC __________________ Spency. PIC Micro's - Your mind is the limit PIC's and interfacing with other devices - a PIC Basic Guide @ digital-diy.net

25th May 2008, 01:24 PM	(permalink)
erosennin	Hi Gramo, I saw you reply to a post I had made about Colour Sensing, and clicked around the site you have in your signature. It looks pretty nice, so I've joined it... I'm about to write a post haha, this doesn't mean ETO that I will ditch you... I promise. Well basically, for what I want to do, there are 3 PWMs and the user will enter the required duty from 0 to 255, and each controls the brightness of a series of RGB leds... Thank you for your advice. __________________ What is a joule per second?