Electronic Circuits and Projects Forum



3 PWM with pic16f627a?

  1. 18th March 2010 05:15 AM #1
    JeanTech JeanTech is offline

    3 PWM with pic16f627a?

    Hi there

    I would like to build a RGB led controller with a pic16f627. The problem is that it only has one PWM channel. It has 3 timers as well, Tmr0,Tmr1 and Tmr2.

    Is there a way to use PWM on 2 other channels using software? The pic must also be able to accept serial data while PWM is on.

    I'm currently programming in C.

    Thanks in advance
    JeanTech
  2. 18th March 2010 12:46 PM #2
    jimlovell777 jimlovell777 is offline
    Is there another task you'd like to perform with the microcontroller? If not you have plenty of room to implement PWM in software. What C compiler do you use?
    0
  3. 18th March 2010 02:01 PM Thread Starter #3
    JeanTech JeanTech is offline
    Hi there

    The only other task besides PWM, is to accept incoming serial data. I use mikroC compiler. How would the code look in C to use PWM in software?

    Thanks in advance
    JeanTech
    0
  4. 18th March 2010 02:45 PM #4
    Mike, K8LH Mike, K8LH is offline
    JeanTech, There are probably a few qualifiers for using software PWM.

    (1) What is the desired frequency (PWM period)?
    (2) How many duty cycle "steps" or "levels" do you require?
    (3) What is the mcu clock speed (4, 8, 12, 16 MHz)?
    (4) How many channels? Three for a single RGB LED?

    Regards, Mike
    0
  5. 18th March 2010 07:05 PM Thread Starter #5
    JeanTech JeanTech is offline
    Hi there

    1) Desired PWM frequency - 1000.
    2) Levels I require - 0 to 255 ( 1 - 100%)
    3) clock speed - 4 Mhz
    4) channels - 3 channels

    Thanks
    JeanTech
    0
  6. 18th March 2010 11:38 PM #6
    Mike, K8LH Mike, K8LH is offline
    Hi JeanTech,

    Generating 256 duty cycle steps with a 1000-Hz period translates to a step time of around 4-usecs. This can be difficult to achieve in software on a 4-MHz PIC.

    I have developed a method recently using BAM (Bit Angle Modulation) which could provide a 2-usec "step" size and a 1953-Hz (512-usec) period on a 4-MHz PIC but I haven't found an easy way to reproduce the driver in C. Sorry!

    May I ask if you are related to the JeanTech that produces computer cases?

    Regards, Mike
    0
    Last edited by Mike, K8LH; 19th March 2010 at 12:04 AM.
  7. 19th March 2010 05:16 AM Thread Starter #7
    JeanTech JeanTech is offline
    Hi Mike

    thanks for all the help. I think I can upgrade my clock speed to 12mhz, so that should work.

    No I'm not related to JeanTech who produces pc cases :-)

    thanks for the help
    0
Tags
« Pic16f877a | Assembly - Help Please »
Similar Threads
Thread Starter Forum Replies Last Post
pic16f627a USB connection JeanTech Microcontrollers 4 5th March 2010, 04:12 PM
PIC16F627A will not program? i_build_stuff Microcontrollers 8 8th June 2009, 01:22 PM
PIC16F627A Upgrade...? tlambertsen Microcontrollers 6 28th October 2008, 03:06 PM
Differences between PIC16F627 and PIC16F627A Cypher Microcontrollers 3 14th March 2007, 01:17 PM
Help with the PIC16F627A, cant get ports to act right FusionITR Microcontrollers 6 16th March 2006, 11:59 AM
Electronic Circuits  |  Learning Electronics

Join our community with over 100,000 Members! It's free, easy and when you're logged in you have many more features! Click to register.
Page Time: 0.07249 seconds      Memory: 7,427 KB      Queries: 16      Templates: 0