FPGA Central

Ok what I am doing is measuring the width on a scope between the toggles o
the pin. So say I measure 100us I divide that by the value in my prese
value which gives me the update rate of the timer. Now since I dont hav
any prescalers set I would assume that this value should be the main cloc
value of the DSP i.e. 150MHz = about 6.6ns, but I dont get this I get twic
this i.e. about 13.4ns. So I can only think that there is something I hav
overlooked. As far as I can see there is only a prescaler on the timer an
one on the clock HSPCLK to the timer and both prescalers are set to 1. So
would imagine that the timer should be updated at 150MHz

Jo

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maxascent wrote:
> Ok what I am doing is measuring the width on a scope between the toggles of
> the pin. So say I measure 100us I divide that by the value in my preset
> value which gives me the update rate of the timer. Now since I dont have
> any prescalers set I would assume that this value should be the main clock
> value of the DSP i.e. 150MHz = about 6.6ns, but I dont get this I get twice
> this i.e. about 13.4ns. So I can only think that there is something I have
> overlooked. As far as I can see there is only a prescaler on the timer and
> one on the clock HSPCLK to the timer and both prescalers are set to 1. So I
> would imagine that the timer should be updated at 150MHz

One last dumb question from me, and then I have to give up because I
don't know the processor or have the manual.

What you see on the scope is a square wave. The time between toggles is
the time of a top or a bottom. You aren't measuring the complete period,
are you? That would account for the timings you see.

Jerry
--
Engineering is the art of making what you want from things you can get.
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