Re: [uCsimm] SPI

From: Florian G. Pflug (
Date: Fri May 12 2000 - 05:17:53 EDT

On Fri, May 12, 2000 at 12:13:17PM +0930, Reynolds, Alfred wrote:
> How much skew is there in RTLinux periodic timers? Can they be within 62.5us
> of the expected time? I know interrupts on RTLinux on the uCSimm take about
> 130us to be serviced, so using the interrupt method for filling the buffer
> won't work.
> To do the CBR stream, I am going to try the easy way with the SPI and trying
> to service it quick enough. If it doesn't work then I will build some
> supporting circuitry :)
> Alfred
> This message resent by the list server

We have this running with RT-Interrupts, but what you get a at best
"neary-CBR" - you have apporixmatly 1 bit "pause" after 16 Bit Transfered.

You could get a better result if you use a periodic timer, and let it fire
after lets say 15 bits are transfered - and then poll for the transfer to

Or you connect a counter to the SPI-Clock, and by this generate you own
Interrupt after 15 (or 14) transfered bits.

Greetings, Florian Pflug
This message resent by the list server

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