I don't think you can do this on a PIC because there is only one
interrupt vector. You could do this on a Motorola (for example), but
even then, I wouldn't recomend it. Getting interrupted from an interrupt
can cause all kinds of problems (stack, endless loops, memory
corruption, etc). Recursive interrupt functions are a nightmare.

Having said that, in your application, maybe you could start the
interrupt the way you suggest, then load your timer, and poll the timer
status flag to see if it has expired.

Brad Stevenson, CET
The DPL Group - Telecom Techniques
506-635-1055 or 1-800-561-8880
http://www.dpl.ca

> -----Original Message-----
> From: James & Ili [SMTP:jandi@MPSI.NET]
> Sent: Thursday, March 12, 1998 1:39 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Interrupt inside an interrupt?
>
> Greetings,
>         I'm in the middle of trying to make some code to do RS232
> reception
> and have a question. My idea is to have an interrupt on the start
> bit, then load the timer with some value and wait for it to time out
> and generate another interrupt at which time I can check the data
> line again to get the bit in. Then reset the timer with another
> value.. etc... Is it possible to have one interrupt more or less
> inside another interrupt? If so is there anything special that needs
> to be done?
>         Thanks for your time!
> James