On Mon, 14 Feb 2005 23:21:48 +0100, "Ulf Samuelsson" <ulf@a-t-m-e-l.com> wrote:
>Never tried, but I think you can chain two 16 bit timers on the AT91.
>If you dont want to waste timers:
>
>If you run at 50 Mhz, and have a top value of 50000, you also get a
>free clock tick for an operating system.
>
>The clock tick will update the upper 16 bits for the 32 bit timer,
>and the capture interrupt will read from the SRAM location.
>Is this to reduce power consumption or to reduce interrupt rates?.
I was thinking of trying to connect timer2 to timer1 to see if I can get a 32 bit capture to work. I
wasn't sure if that would work. I'm using tioa2 to get a 16 bit capture. I'll give that a try.
I may need to read some very low rpm's, so 16 bits might not be enough.
I'm running timer0 as the system timer.
David
Reply by Ulf Samuelsson●February 14, 20052005-02-14
Never tried, but I think you can chain two 16 bit timers on the AT91.
If you dont want to waste timers:
If you run at 50 Mhz, and have a top value of 50000, you also get a
free clock tick for an operating system.
The clock tick will update the upper 16 bits for the 32 bit timer,
and the capture interrupt will read from the SRAM location.
Is this to reduce power consumption or to reduce interrupt rates?.
--
Best Regards,
Ulf Samuelsson
ulf@a-t-m-e-l.com
This message is intended to be my own personal view and it
may or may not be shared by my employer Atmel Nordic AB
"David Lawson" <david_lawson@xdevnullx.com> skrev i meddelandet
news:l7r111h8hktk8em5hkq3n22t5mhn4ctmft@4ax.com...
> I'm trying to find an ARM chip that has a 32 bit capture timer. I can't
find any from Atmel.
> Does anyone else make such a thing?
>
>
Reply by Nicholas O. Lindan●February 14, 20052005-02-14
"David Lawson" <david_lawson@xdevnullx.com> wrote in message
> I'm trying to find an ARM chip that has a 32 bit capture timer. I can't find
any from Atmel.
> Does anyone else make such a thing?
Yes, but in software. With a 65MHz input to the timer the overflow rate is
1 KHz and easily handled by a 6-instruction software interrupt routine.
At ~1-2 MHz the rate is 30 - 60Hz. By reading the software counter before and
after reading the hardware timer it is possible to get 100% reliable on-the-fly
counts.
--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
Reply by Richard Tuffin●February 14, 20052005-02-14
"David Lawson" wrote I'm trying to find an ARM chip that has a 32 bit
capture timer. I can't find any from Atmel.