+ Post New Thread
Results 1 to 4 of 4
  1. #1
    Member level 1
    Points: 2,917, Level: 12

    Join Date
    Aug 2004
    Location
    Grenoble,France
    Posts
    40
    Helped
    8 / 8
    Points
    2,917
    Level
    12

    Use of CPLD/FPGA for a newbie's laser project

    Hello

    I have to design a project , a laser controller. The controller will have a trigger mode to pulse the laser about 100kHz. At first, I thought to use the pwm peripheric of a microcontroller. The problem is the dutyy cycle which has to be adjust with a photodiode. ( the diode current will be stop as soon as the laser pulse is emitted).
    So maybe that le logic circuit driving the current amplifier could be made with a cpld/fpga. The issue is I'm a newbie foor this technology.
    so I have a few questions :
    - CPLD or FPGA?
    - How evaluate the size (number of cells ) needed for a project ?
    - Do you know a free or low cost developpment sytem ( software and hardare ) ? this can be a constraint to chose the maker.
    - I don't need a lot of IO, and I prefer a hand soldering chip.


    thanks

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 260,279, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    45,460
    Helped
    13829 / 13829
    Points
    260,279
    Level
    100

    Re: Use of CPLD/FPGA for a newbie's laser project

    You need to specify the intended controller function (e.g. processing purely digital or digitized analog input signals) to decide about a suitable programmable logic platform.

    However, these days small flashed based FPGA are successively replacing simple CPLD (or even marketed as "CPLD"). Altera/Intel MAX10 series is one example. Chips and development boards are cheap, basic software is free.

    Technically I don't understand your concept of controlling the laser pulse width. A pulsed laser is usually operated with nanosecond pulse width, there's little chance to modify the pulse in instantaneous feedback. Controlling the pulse width or current of the next pulse based on an averaged power measurement makes more sense.



    •   AltAdvertisement

        
       

  3. #3
    Member level 1
    Points: 2,917, Level: 12

    Join Date
    Aug 2004
    Location
    Grenoble,France
    Posts
    40
    Helped
    8 / 8
    Points
    2,917
    Level
    12

    Re: Use of CPLD/FPGA for a newbie's laser project

    It's not the pulse width that I want to adjust. The pulse is emitted when the laser has enought energy to be emitted, and this energy is bring via the current. So I want to stop the current in the laser diode when the pulse is emitted for going to another pulse.
    The CPLD/FPGA will only drive control logic of the current driver, and there is a micro controller (pic ) fior the GUI, the laser security, and temperature controller.



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 260,279, Level: 100
    Awards:
    1st Helpful Member

    Join Date
    Jan 2008
    Location
    Bochum, Germany
    Posts
    45,460
    Helped
    13829 / 13829
    Points
    260,279
    Level
    100

    Re: Use of CPLD/FPGA for a newbie's laser project

    t's not the pulse width that I want to adjust. The pulse is emitted when the laser has enought energy to be emitted, and this energy is bring via the current. So I want to stop the current in the laser diode when the pulse is emitted for going to another pulse.
    Makes no sense referring to post #1
    The problem is the dutyy cycle which has to be adjust with a photodiode. ( the diode current will be stop as soon as the laser pulse is emitted).
    Anyway, you'll hopefully know what you want to achieve. No doubt that it's possible with a FPGA.



--[[ ]]--