LPC2148 Reset Problem

Discussion in 'Embedded Systems and Microcontrollers' started by praveen130789, Mar 11, 2014.

  1. praveen130789

    Thread Starter New Member

    Mar 11, 2014
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    Hi, i had built a circuit of LPC2148 Development Board, which uses FT232RL to download the program through USB, I am unable to find out whats the problem is all about, everything is going fine including downloading the hex file to the controller, but after the hex file is downloaded, the program is not getting executed automatically, also when i press the reset button also the program is not executing, however if i switch off and switch on the board twice or thrice, the programs runs. what may be the problem ???

    I have attached the circuit below, all the grounds are made common in the circuit.
     
  2. pwdixon

    Member

    Oct 11, 2012
    488
    56
    Is this a professional pcb or a prototype you have assembled yourself?
    What are the physical distances between the crystal/caps/processor?
     
  3. pwdixon

    Member

    Oct 11, 2012
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    I don't see much in the way of decoupling on the processor power supply pins.
     
  4. praveen130789

    Thread Starter New Member

    Mar 11, 2014
    3
    0
    Its just a prototyping PCB i have done, Physical distance between processor and crystal is ~ 0.7 cms.

    Voltages on controller power pins is almost 3.6V, will the decoupling on controller power pins solve the issue of reset ??

    Initially Reset pin is High when pressed the reset switch, voltage on reset pin goes to exact zero i have checked it in oscilloscope
     
  5. pwdixon

    Member

    Oct 11, 2012
    488
    56
    Processors usually want the crystal and caps close so 0.7cm is pretty good.

    Decoupling can't make things worse and could well sort the problem it's worth a try.
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Adding decoupling caps will solve a myriad of weirdnesses.
     
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