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Best PIC for Project?

Discussion in 'Microcontrollers' started by PJ Adams, May 7, 2007.

  1. PJ Adams

    PJ Adams New Member

    Joined:
    Jan 15, 2004
    Messages:
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    Hello Paco - it is a small world - remember me?

    I was on the DataQ forum as well - was spoke on the forum about a dyno, (PJAdams user)

    I also got a DataQ 148U - but also came to the conclusion it was not what was best. Also - I found mine to be somewhat unreliable. It kept 'freezing' and needed resetting.

    I used the soundcard on the PC to sample inputs - and it worked (very well actually) - however - it was not accurate enough & PC timing 'wobbles'.

    I found a simple Parallel data logger on the net (build it yourself) that samples up to 1Mhz - digital inputs only. That would of worked - but again - it is based on PC timing - which can 'wobble'.

    I decided that timing is a critical element to correct work out (accurately) torque - and therefore it had to be an outside hardware timer - hence the PIC route.

    I'm not an electronics guy & I'm struggling - but I'm going to order the PICKit2 & see where it leads me.


    Regards

    Paul (PJ Adams)
     
  2. pacoraap

    pacoraap New Member

    Joined:
    May 10, 2007
    Messages:
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    Hi Paul,

    Yes small world.
    But in the end we meet again.

    Some one else building a modelcar dyno has chimed in on my project.
    He already said that the DATAQ will not perform the job.
    He also tried Serial but is now measuring torque by strain gauge and parallel port.
    For your inertia drum this is not usable.
    I like to use the inertia disk to keep all simple to rebuild.
    The dataq 148 can still be used to measure all analog signals as this is what I intend to do.

    I was told the pc clock would be sufficient to produce data.
    Cant you measure the wobble of the pc clock and take that in the freq calc?

    I was advised to measure 20 to 30 revs measure start and end time and use the average as RPS. With high speed clock this would be the best possible and still have reasonble accuracy for RPM collection.

    QueryPerformanceCounter Lib "kernel32" (x As Currency) As Boolean
    QueryPerformanceFrequency Lib "kernel32" (x As Currency) As Boolean
    These API's can be use to determine timestamps and frequencies.
    You can also calcualte the differences due to the API calls according the MSDN page http://support.microsoft.com/kb/172338

    I am struggling to program in VB although I get some help.
    The mechanics are no problem and also the sensors are working 100%
    Quited to use the cheap F/V conveter by LM2417.

    Keep in touch,

    Paco
     

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