LPC24xx Toggling between Timer and Capture Functionality

Hi all,

I am working with LPC 2468 in an embeddedartists board.

In my design I am interfacing to 8 PWM capture based sensors(PT100 using
UTI and Max sensor).
To achieve it I used the 2 PWM captures and 6 timer (T1 T2 T3 CAP 0&1)
captures. (all are hard wired )

But now I face a design complexity where I have no free timers to be used
for adding delay in the main code. T0 is being used for Ethernet uip
code.

I had an idea to toggle between timer and capture functionality in
software. All the capture signals are hardwired on the board. But this is
not working. When I turn on the timer functionality and turn it off later
it messes up with the counter in the sensor.

Is there a way to do it where one can switch in software between timer and
capture functionality. My sensor capture code does not use the timer from
the same line.

For eg:: My idea was to use Timer 1 while using cap functionality of Timer
2 and to use Timer 2 while using the capture functionality of Timer 1.

I set PCONP_bit.PCTIM1 ,2,3 = 0 at the end of the capture code. I also
reset the PINSEL = 0 after the capture code is finished.

Am I missing something here??

Cheers
---------------------------------------
Posted through http://www.EmbeddedRelated.com

On Thu, 07 Jan 2016 09:49:48 -0600, sns22 wrote:

> Hi all,
> 
> I am working with LPC 2468 in an embeddedartists board.
> 
> In my design I am interfacing to 8 PWM capture based sensors(PT100 using
> UTI and Max sensor).
> To achieve it I used the 2 PWM captures and 6 timer (T1 T2 T3 CAP 0&1)
> captures. (all are hard wired )
> 
> But now I face a design complexity where I have no free timers to be
> used for adding delay in the main code. T0 is being used for Ethernet
> uip code.
> 
> I had an idea to toggle between timer and capture functionality in
> software. All the capture signals are hardwired on the board. But this
> is not working. When I turn on the timer functionality and turn it off
> later it messes up with the counter in the sensor.
> 
> Is there a way to do it where one can switch in software between timer
> and capture functionality. My sensor capture code does not use the timer
> from the same line.
> 
> For eg:: My idea was to use Timer 1 while using cap functionality of
> Timer 2 and to use Timer 2 while using the capture functionality of
> Timer 1.
> 
> I set PCONP_bit.PCTIM1 ,2,3 = 0 at the end of the capture code. I also
> reset the PINSEL = 0 after the capture code is finished.
> 
> Am I missing something here??
> 
> Cheers ---------------------------------------
> Posted through http://www.EmbeddedRelated.com

I think you may have just gone and selected hardware that doesn't have 
enough timers.

HOWEVER: some of chips that I've used that have capture-compare 
functionality allow you to set the timer to free-run, and interrupt you 
on a roll-over.  Then the capture function just snags the timer count on 
an external event.

If you just need a heartbeat, then you could use the roll-over as your 
heartbeat, and use the capture-compare functionality separately.

Alternately, the part number sounds ARM-ish -- can you use the core timer 
for Ethernet, and the hardware timers for whatever it is you're doing?

-- 
www.wescottdesign.com