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Thread: PICs and PWM

  1. #1
    philo Newbie
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    Default PICs and PWM

    Any chance of some advice?
    I need to design an LED dimming circuit to be used as a speedo backlight. I will need to have two inputs corresponding to "Dimmer" and "Brighter" and use a PWM output to the LEDs.
    At university, I did a similar project using a 16F84 and the output derived from a simple count up or down. I am considering using the same for this project, but I am sure that there will be a more suitable PIC for this application. I've checked the Microchip website but the sheer number of types available is a bit daunting!


  2. #2
    Ayne Newbie
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    PIC16F877A. >>> PWM max. resolution is 10 bit
    with 8 KB flash memory 40 pins

  3. #3
    Super Moderator Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent
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    Pick one with internal PWM - the 16F628 (the 'modern' replacement for the antique 16F84) has a single PWM channel, and also an internal 4MHz oscillator. There are many others which would do the job, but that one should be familiar to you.
    PIC programmer software, and PIC Tutorials at:
    http://www.winpicprog.co.uk

  4. #4
    Super Moderator Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent
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    Quote Originally Posted by Ayne
    PIC16F877A. >>> PWM max. resolution is 10 bit
    with 8 KBflsh memory 40 pins
    Perhaps 40 pins is a bit of overkill for dimming an LED?.
    PIC programmer software, and PIC Tutorials at:
    http://www.winpicprog.co.uk

  5. #5
    philo Newbie
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    Thanks for your help, I'll give it a try

  6. #6
    justDIY Good justDIY Good
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    12F683 with one pwm channel, internall 8mhz osc and only 8 pins.
    If you don't have a planet, what good are gold bars?

    want to contact me directly? gmail gordonthree
    check out my project website: http://projects.dimension-x.net
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  7. #7
    phalanx Newbie
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    Quote Originally Posted by justDIY
    12F683 with one pwm channel, internall 8mhz osc and only 8 pins.
    The 12F683 is a great little chip. I use it in a number of compact designs. Not only does it have PWM, it also has 3 timers including a 16-bit one and one with a period register, interrupts, a comparator, A/D converter, and interrupt on change pins.

    You can get them for about $1 in quantities of 25 from Mouser.

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