Lpc2000

Just a though, but what about, in the interrupt routine, switch the
pin(s) to GPIO input, read the pin state, then switch the pin(s)
back to the original function?

Regards
-Bill Knight
R O SoftWare



On Sun, 04 Apr 2004 16:00:23 -0000, bobbruce000 wrote:

>--- In lpc2000@yahoogroups.com, "moostieuk" <moostieuk@y...> wrote:
>> I've tried this before, it appears that once you've put the pins
>> capture/compare mode you cannot read the state directly from the
>> pin.  
>> 
>> I was reading a PWM signal, so in the end I just ended up creating
>> a state machine and in the capture interrupt change the edge
>> triggering for the next capture.

>A state machine won't work for my application.  I suppose I can
>use the capture pins to trigger the interrupt, and read the state
>from another set of pins that mirror the values.  But what a waste
>of pins!  I suppose I could move to a 2114 to get some extra pins,
>but then I need to squeeze the RAM requirements down to only 16k.
>I hate tradeoffs.

>The Philips User Manual is clearly wrong about this.  I read the
>docs carefully, believed what they said, and now I have to toss a
>couple of prototype boards in the trash and rewrite the software
>when I am already behind schedule.  They should fix their dang
>docs and not leave this for the next engineer to trip over.  This
>isn't a printed manual, it is just a PDF file, so it shouldn't be
>much effort to fix. 

>    -bob


>> --- In lpc2000@yahoogroups.com, "bobbruce000" <bobbruce000@y...> wrote:
>> > I have several pins configured as capture pins which interrupt on
>> > either a rising of falling edge.  Then in the interrupt handler
>> > I read the IOPIN register to get the value.
>> > 
>> > According the description of the IOPIN register on page 81 of the
>> > Philips 210x User Manual, this should work.  I quote:
>> > 
>> >   "The current state of the port pins can always be read from
>> >     this register, regardless of pin direction and mode."
>> > 
>> > But it doesn't seem to work.  I have double and triple checked
>> > my code, and I 95% sure this is not a software bug.  The capture
>> > pins always read zero.
>> > 
>> > Is the user manual wrong?
>> > 
>> >     -bob



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