Jump to content


  • Content Count

  • Joined

  • Last visited

Posts posted by veimmone

  1. Hi,


    The frequency of the internal oscillator doesn't yet determine the actual clock frequency of the CPU - the PLL gets in the mix, too.


    From your observation of a 5s interval, I bet your CPU is running at 50 MHz.


    Suggest you download TI's TivaWare, then take a look at the source of the SysCtlClockSet function and the documentation as well.

  2. Hi all,


    I created a 3D model of the Stellaris LaunchPad and thought I could share it, so here goes:



    (attaching .STEP files is not allowed, so Dropbox for now)


    I included all components I thought had some external relevance (and the chip itself for looks). All the pin positions are according to the LaunchPad manual, so they should be accurate. Other positions have been measured with a caliper, but as always - trust but verify. Dimensions of the pins themselves (apart from height) should not be trusted, they're mostly for looks.


    If you need it in another format, ask and you might receive.


  3. Hello!


    My first post here, I've been reading the forum a while but now I decided to show myself.


    The LM4F120 indeed does not have the hardware QEI modules available on the higher-end models. So you'll need a pure software solution.


    I'm currently working on a final year mechatronics project at Aalto University (in Finland), and the device I'm building has three quadrature encoders. I'm using the SLaunchPad as the controller and am now writing my own support libraries on top of StellarisWare. One such library module is a software QEI, having most of the features that the hardware API has, excluding velocity measurement.


    Just a fair warning; you can't run a very fast encoder on a software QEI, let alone multiple encoders. I have a 1000 ppr encoder which I spun at increasing speeds until the software reported an error condition (both channels having an active interrupt at the same time). I got to around 2000-3000 rpm, and the decoding was done in 4x mode, so both edges on both channels were counted. Using an idle-while loop counter, I estimated the CPU usage at that point to be around 50%.


    I'm not yet publish-confident with the library, but if you give me your email address, I'll send you the source code. The library supports counting in 1x, 2x and 4x modes, has optional support for Z channel and autoconfiguration for the pins.

  • Create New...