[Tinyos-devel] Bug in Msp430TimerControl.nc interface

[Vlado Handziski]

I have modified the interface to match the implementation. This way is
better because keeping it bool would limit the config to only capture on
rising or on falling edges, but not on both or none. This being HAL, all
options should be exported to the user.

Vlado

On Tue, May 20, 2008 at 05:55, Eric Decker <cire831 at gmail.com> wrote:

> Kevin and I implemented a hardware assisted s/w uart using Timer A2 and in
> the process of debugging I found the following problem:
> In tos/chips/msp430/timer/Msp430TimerControl.nc setControlAsCapture is
> defined as:
>
>     async command void setControlAsCapture(bool low_to_high);
>
> note the bool low_to_high.
>
> But in the actual implementation in
> tos/chips/msp430/timer/Msp430TimerCapComP.nc
>
>   async command void Control.setControlAsCapture( uint8_t cm )
>   {
>      TxCCTLx = captureControl( cm );
>   }
>
> and captureControl looks like:
>
>   uint16_t captureControl(uint8_t l_cm)
>   {
> =>  cc_t x = {
>       cm : l_cm & 0x03,    // capture on rising edge
>       ccis : 0,  // capture/compare input select
>       clld : 0,  // TBCL1 loads on write to TBCCR1
>       cap : 1,   // compare mode
>       scs : 1,   // synchronous capture mode
>       ccie : 0,  // capture compare interrupt enable
>     };
>     return CC2int(x);
>   }
>
>
> So the interface definition lies.  The compiler doesn't catch the
> definition mismatch because bool is a uint8_t.
>
> I would propose:
>
> Index: timer/Msp430TimerCapComP.nc
> ===================================================================
> RCS file:
> /cvsroot/tinyos/tinyos-2.x/tos/chips/msp430/timer/Msp430TimerCapComP.nc,v
> retrieving revision 1.3
> diff -u -r1.3 Msp430TimerCapComP.nc
> --- timer/Msp430TimerCapComP.nc 16 Feb 2008 20:03:51 -0000      1.3
> +++ timer/Msp430TimerCapComP.nc 20 May 2008 03:53:11 -0000
> @@ -58,10 +58,10 @@
>      return CC2int(x);
>    }
>
> -  uint16_t captureControl(uint8_t l_cm)
> +  uint16_t captureControl(bool low_to_high)
>    {
>      cc_t x = {
> -      cm : l_cm & 0x03,    // capture on rising edge
> +      cm : (low_to_high ? 1 : 2), // 0b01 gives rising, 0b10 gives falling
>        ccis : 0,  // capture/compare input select
>        clld : 0,  // TBCL1 loads on write to TBCCR1
>        cap : 1,   // compare mode
>
>
> who supports msp430 timers these days?
>
> --
> Eric B. Decker
> Senior (over 50 :-) Researcher
> Autonomous Systems Lab
> Jack Baskin School of Engineering
> UCSC
>
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>
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