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??


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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?

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Tim Wescott

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