serial in command

neaor

Hi, i was wondering if there is any way to have the stamp check for serial input commands while executing a pulse width modulation command. ie do the pulse width modulation command until the serial input says to stop. currently, i only know how to set the stamp to do the pulse width modulation for a set amount of time, not until the user inputs something serially. Thanks.

Bruce Bates

neaor -

Fundamentally, the PBASIC Stamp is a single tasking processor, and as such can only perform one task at a time. However, if the PWM process were done by a separate off-board co-processor (as is often done) then you CAN do both.

Parallax offers two different co-processors, for performing just such tasks. Here they are for your perusal:

PWMPAL: http://www.parallax.com/detail.asp?product_id=28020

PSC: http://www.parallax.com/detail.asp?product_id=28023

As you can see by the descriptions of each, on the Parallax web site above, the PSC is more geared to the specific task of driving R/C servos, which is a common application for the Basic Stamps.

There are also others who offer PWM co-processors: http://www.awce.com/pak5.htm .

Regards,

Bruce Bates

Tom Walker

And, depending on the needed frequency and pulse width, you could actually "roll your own" PWM routine around a "serial with timeout". Be advised, this could only be done if you needed EXTREMELY SLOW PWM... I just present the idea to emphasize that clever programming can overcome percieved limitations (single-tasking, for example) of a microcontroller.

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