Lpc2000

Hi
I need to use an external pulse to reset one of the timers of an 
LPC2294. The latency of the FIQ from an external interrupt is too 
long, so I wondered if there is any clever technique that anyone has 
thought of to achieve the same thing faster.

Sadly, the capture pins aren't able to provide a nice external 
hardware reset input.

If anyone has any suggestions they would be gratefully received.

many thanks
Simon

--- In lpc2000@yahoogroups.com, "itsjustimpossible" <simonjh@b...> 
wrote:
> 
> I need to use an external pulse to reset one of the timers of an 
> LPC2294. The latency of the FIQ from an external interrupt is too 
> long, so I wondered if there is any clever technique that anyone 
has 
> thought of to achieve the same thing faster.
> 
> Sadly, the capture pins aren't able to provide a nice external 
> hardware reset input.

Use a capture pin and enable the capture interrupt.  In the capture 
interrupt handler, remember the captured value as the time where you 
would have reset the timer.  When you later need the timer value, 
subtract the remembered value.

Karl Olsen

--- In lpc2000@yahoogroups.com, "itsjustimpossible" <simonjh@b...> 
wrote:
> 
> I need to use an external pulse to reset one of the timers of an 
> LPC2294. The latency of the FIQ from an external interrupt is too 
> long, so I wondered if there is any clever technique that anyone 
has 
> thought of to achieve the same thing faster.
> 
> Sadly, the capture pins aren't able to provide a nice external 
> hardware reset input.

Use a capture pin and enable the capture interrupt.  In the capture 
interrupt handler, remember the captured value as the time where you 
would have reset the timer.  When you later need the timer value, 
subtract the remembered value.

Karl Olsen

Friendly amendment,  during the capture interrupt service routine
disable all other higher priority interrupts while handling the
setting of the timer. Read the captured value, read the current timer
value, subtract captured from current value, count the number of
cycles this took write the result of the subtraction + cycles into timer. 

Cheers, Bob

--- In lpc2000@yahoogroups.com, "Karl Olsen" <kro@p...> wrote:

> 
> --- In lpc2000@yahoogroups.com, "itsjustimpossible" <simonjh@b...> 
> wrote:
> > 
> > I need to use an external pulse to reset one of the timers of an 
> > LPC2294. The latency of the FIQ from an external interrupt is too 
> > long, so I wondered if there is any clever technique that anyone 
> has 
> > thought of to achieve the same thing faster.
> > 
> > Sadly, the capture pins aren't able to provide a nice external 
> > hardware reset input.
> 
> Use a capture pin and enable the capture interrupt.  In the capture 
> interrupt handler, remember the captured value as the time where you 
> would have reset the timer.  When you later need the timer value, 
> subtract the remembered value.
> 
> Karl Olsen

This is slightly off topic but since this is a Philips micro and I also 
use them as a support micro for the LPC2xxx .....

<Posted to comp.arch.embedded>

I just received some samples of the LPC903 the other day and it hit me. 
Where is the specification for the ICP? I know it only needs 
clock,data,reset but I can't any find a document that describes the 
timing and format for that section.

I know that you can use the eval board plus an adaptor to talk to these 
things but it is usual for a manufacturer to release the programming 
details. I have been using PIC12's in this area and there is no shortage 
of info on programming these miserable little (useful) suckers.

Does anybody know anything about the ICP spec for the LPC903s?

TIA,
Peter



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Philips Apps have just posted the ICP spec and source code for the
ISP/ICP bridge software on the LCP900 users group:-

http://groups.yahoo.com/group/lpc900_users/files/

Best Regards,
For and On Behalf of Adilam Electronics
 
 
David Kay
Field Application Engineer - New Zealand
 
Tel  : +64 3 341 3050
Mob: +64 21 664 351
Fax : 0800 366 247
Email : david.kay@...
 
 
local focus_global reach - That's adilam !

-----Original Message-----
From: Peter Jakacki [mailto:peterjak@...] 
Sent: Thursday, 20 January 2005 1:42 p.m.
To: lpc2000@yahoogroups.com
Subject: [lpc2000] OT: LPC903 ICP spec


This is slightly off topic but since this is a Philips micro and I also 
use them as a support micro for the LPC2xxx .....

<Posted to comp.arch.embedded>

I just received some samples of the LPC903 the other day and it hit me. 
Where is the specification for the ICP? I know it only needs 
clock,data,reset but I can't any find a document that describes the 
timing and format for that section.

I know that you can use the eval board plus an adaptor to talk to these 
things but it is usual for a manufacturer to release the programming 
details. I have been using PIC12's in this area and there is no shortage

of info on programming these miserable little (useful) suckers.

Does anybody know anything about the ICP spec for the LPC903s?

TIA,
Peter



-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.7.1 - Release Date: 1/19/05



 
Yahoo! Groups Links

Thanks again Dave, I've joined, grabbed the files, and left a message. 
Maybe you could help some more? :)

- Peter

David Kay wrote:

>Philips Apps have just posted the ICP spec and source code for the
>ISP/ICP bridge software on the LCP900 users group:-
>  
>



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Checked by AVG Anti-Virus.
Version: 7.0.300 / Virus Database: 265.7.1 - Release Date: 1/19/05

--- In lpc2000@yahoogroups.com, "lpc2100_fan" <lpc2100_fan@y...> 
wrote:
> 
> 
> Friendly amendment,  during the capture interrupt service routine
> disable all other higher priority interrupts while handling the
> setting of the timer. Read the captured value, read the current 
timer
> value, subtract captured from current value, count the number of
> cycles this took write the result of the subtraction + cycles into 
timer. 
> 
> Cheers, Bob

Thanks for all the suggestions, I gave it a try and it works very 
nicely. One of those useful techniques that I will have to remember, 
makes sense when you think about it.

thanks again
Simon