TIMER1 Newbie Question

Hi,

Although I have Googled TIMER1 info. on MicroChip devices, as a novice,
I am somewhat confused and would appreciate a little help.

I have a project I am developing where I wish to count the number of
pulses from a 1 MHz square wave source.  (I am measuring the time a
light beam has been broken)

Now, the 16 bits of Timer1 will allow me to count up to 65535 pulses,
which at 1 MHz should give me a window of around a 1/15th of a second.
That is good enough for me, as the light beam will be broken by a
small, quite a fast moving object - around 5 metres per sec and the
object is only 40 mm long - I figure around 1/125th of a second to pass
through the beam.

HOWEVER, I cannot for the life of me figure out what I am supposed to
be doing with Timer1 and which pin I connect the external pulse to.

Any pointers, tips regarding Timer1 and/or code for
initialising/reading it will be great?  I have a feeling I should be
using Timer1 in Asynchronous Counter Mode - is that correct?

Cap'n Ahab

Cap'n Ahab wrote:
> Hi,
>
> Although I have Googled TIMER1 info. on MicroChip devices, as a novice,
> I am somewhat confused and would appreciate a little help.
>
> I have a project I am developing where I wish to count the number of
> pulses from a 1 MHz square wave source.  (I am measuring the time a
> light beam has been broken)
>
> Now, the 16 bits of Timer1 will allow me to count up to 65535 pulses,
> which at 1 MHz should give me a window of around a 1/15th of a second.
> That is good enough for me, as the light beam will be broken by a
> small, quite a fast moving object - around 5 metres per sec and the
> object is only 40 mm long - I figure around 1/125th of a second to pass
> through the beam.
>
> HOWEVER, I cannot for the life of me figure out what I am supposed to
> be doing with Timer1 and which pin I connect the external pulse to.

T1CKI see pinout for the device your using

>
> Any pointers, tips regarding Timer1 and/or code for
> initialising/reading it will be great?

see reference manual DS33023 Example 12-2 and 12-3.

 I have a feeling I should be
> using Timer1 in Asynchronous Counter Mode - is that correct?

Correct
> 
> Cap'n Ahab