Peter,
Are you cleaning your spin pulse electronically? That is, make sure that
you are using a Shotsky filter on your key phasor output, otherwise you
will generate false triggers of the sort that you are describing.
I don't see anything wrong with your ISR, so I am suspecting that the
cause of all of your ills is a dirty keyphasor pulse, ESPECIALLY if it
is a Keyphasor pulse on an AMB system.
-Edgar
Peter Wurmsdobler wrote:
> Stuart,
>
> Thanks, I just read the code and it looks nice. Unfortunately,
> I still cannot find he bug in my rt isr, why the isr is called
> twice. Now I tested with debug off and I put the dT in a fifo
> within the real time isr:
>
> hrtime_t spp_now;
> hrtime_t spp_past;
> int spp_dT;
> int spp_dT_past;
> int spp_irqs;
> unsigned int spp_isr( unsigned int irq_number, struct pt_regs *p )
> {
> spp_now = gethrtime();
> spp_dT = (int)(spp_now - spp_past);
> spp_past = spp_now;
> if ( spp_dT < 0 )
> spp_dT = spp_dT_past;
> else
> spp_dT_past = spp_dT;
>
> rtf_put( RSPEED_FIFO, &spp_dT, sizeof(spp_dT) );
>
> rtl_hard_enable_irq( RT_MCM_SPP_IRQ );
>
> return 0;
> }
>
> and in a user space appl I pick them up
>
> int value;
> while ( read( rspeed_fd, &value, sizeof(vlaue) ) > 0 )
> printf("time = %d ns\n", value );
>
> Then I get for 1Hz excitation frequency periodically:
>
> Entering event_fifo_handler
> time = 999894432 ns
> time = 9280 ns
> time = 5952 ns
> time = 6464 ns
> time = 5792 ns
> Leaving event_fifo_handler
>
> What is going on? Do you have an idea?
> peterw
> --
> Dr. Peter Wurmsdobler
>
> CTM - Centre de Transfert des Microtechniques
> 39, av. de l'Observatoire, BP-1445, 25007 Besancon CEDEX 3
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