Hi,

there are more possibilities.

1. You should monitor the pin receiving the serial data and branch on it
to receive only if start bit is to be seen. However, this case the other
things (monitoring buttons) should be fast enough.

2. PicBasic Pro supports IT also. Unfortunately, there is no true ISR.
However, you can attach routines to one of IT events.

3. Write an ISR in assembly (I refer here to the thread "Asm vs C").

I hope this helps.

Imre


On Fri, 12 Nov 1999, Mathew Cohen wrote:

> I am constructing a device that sits on a rs485 network. The device
> constantly listens to the network for information that may relate to its
> device number. The device also has 16 push buttons that need to be monitored
> at the same time. I am currently using a shift register to clock the push
> buttons in.
> The concern is I am using PicBasic Pro and it's serial routine either waits
> for a character berfore continuing on with the rest of the program,which
> does not help tracking the button status.  Or has a time out which the
> lowest timeout  is 1ms. This leaves a lot of time for other thing to be
> missed.
>
> Can someone suggest how this could be done effectively.
>
>
> Mathew Cohen.
>
>