matlab and basic stamp 2 interface problems..

wawloh

hi folks,
i'm trying to interface matlab to my BS2 and if it works, will blink
an LED

bs2 code :
' {$STAMP BS2}
' {$PBASIC 2.5}
' {$PORT COM1}
status_pin VAR Word

main:
SERIN 16,84,[noparse][[/noparse]DEC status_pin]
IF status_pin = 0 THEN LOW 8
IF status_pin = 1 THEN repeat
GOTO main

repeat:
PAUSE 500
HIGH 8
PAUSE 500
LOW 8
GOTO repeat

---

%matlab code :

status_pin = 1;
s=serial('com1')
set(s,'baudrate',9600)
set(s,'terminator','CR')
fopen(s);
fprintf(s,'%s\d',[noparse][[/noparse]status_pin]); %if data is sent, i should see the LED
blinking once this line is executed am i rite??
fclose(s)

any ANY help is very much appreciated..really frustrated with such a
simple code but nothing seems to work?!

Unsoundcode

The baud rate for the serial string should read··SERIN 16,16468,[noparse][[/noparse]DEC status_pin], thats 9600 8 bit no parity inverted.

Hope that helps put you on track

Jeff T.

sylvie369

Okay, I'm new to this myself, and this raises a question.

How do you know when it's inverted and not true? In this example, how did you know?

·

Unsoundcode

The IDE help file SERIN has a fairly good explanation to help get started

the IDE help file said...

Most circuits that work with RS-232 use a line driver/receiver. This component does two things: (1) it converts the ±12 volts of RS-232 to TTL-compatible 0 to 5-volt levels and (2) it inverts the relationship of the voltage levels, so that 5 volts = logic 1 and 0 volts = logic 0.

All BASIC Stamps (except the BS1) have a line receiver on its SIN pin (Rpin = 16).

Jeff T.

sylvie369

Thanks. I see. Bleeped right over that part when I was learning about serial communications.