need guidance

Jose AAG

I have programed a few PlCs but now my boss wants to create our own controller, can some one help me write a little program just an input and an output ( when the input is made the output should make)· I'm using a Stamp1 project board. I'v been reading for two days and have tried a few of the included samples but since I have no experience in basic is a little dificult. Thanks in advance for any help.

Kevin Wood

What are you trying to do with the input & output?

For example, if you press a button (input), an LED will blink (output)...

Jose AAG

that's exactly what i'm trying to do Kevin i belive that's a good start just press the button ( input P0) turn led on (output P4) release button led should go out.

Thanks

Mike Green

Assuming that when you press the button, you connect P0 to ground (Vss) and that the LED is connected from P4 to Vcc via a resistor to limit current:

Wait:
if Pin0 = 1 then Wait
Blink:
Pin4 = 0
pause 250
Pin4 = 1
pause 250
if Pin0 = 1 then Blink
goto Wait

Mike Green

I forgot to initialize the pins. Put the following first:

Dir0 = 0
Dir4 = 1

Kevin Wood

Jose,

I don't have BS1 experience, but can tell you that starting off with a BS2 would be much easier. It uses improved PBasic syntax, and there is more info available.

Take a look at the "What's a Microcontroller" manual, which can be downloaded for free. Chapter three describes doing what you are trying to do, the caveat being that the code is written for the BS2, not the BS1.

A good way to get started with a BS2 is the Summer Special, also known as the RadioShack "What's a Microcontroller" Kit.

But if you are limited to the BS1, keep posting, there are plenty of people here than can help.

Bruce Bates

Mike -

I suspect you need a pull-up resistor on P0, don't you?

Regards,

Bruce Bates

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Jose AAG

Bruce by a pull-up resistor do you mean a 470 ohm resistor ( should that be·connected this way? Vss-to-switch-to-resistor-to-P0)
thanks for the fast responses guys.

Mike Green

Not quite. The pull-up resistor (4.7K to 10K usually) is connected from P0 to Vcc (5V). The switch is connected from P0 to Vss (Ground). The idea is that the pull-up holds the pin at a high level (Vcc) unless the switch is closed. Then the pin is at a low level (ground). The resistor is chosen to limit the amount of current through the switch when it is closed (to 0.5 to 1 ma). The resistor could be larger, but is rarely more than 100K.

You can also have a pull-down resistor with the switch connected from the pin to Vcc, but most sensors and switches are meant to connect a signal line to ground since the ground can also serve as a shield.

Jose AAG

this is what I have and is not working
Vss to Sw to P0
Vdd to 10k to P0
LED Short leg to P4, long leg to 470 ohm- to Vdd and apply the following code

Dir0 = 0
Dir4 = 1

Wait:
if Pin0 = 1 then Wait
Blink:
Pin4 = 0
pause 250
Pin4 = 1
pause 250
if Pin0 = 1 then Blink
goto Wait

As soon as I power up LED blink but when sw makes (closes) Led stops blinking

Post Edited (Jose AAG) : 6/22/2006 9:52:36 PM GMT

allanlane5

Then it sounds like your switch is "normally closed", and is immediately providing a
'zero' to Pin0. When you press it, it 'opens', and lets the pin float.

So, change the "IF Pin0 = 1" to "IF Pin0 = 0".

Jose AAG

It's working · seems that the code was·wrong, one of the " if Pin0 =·# then Wait" was supposed to be a "0" and the other a "1"

Thanks to all of you, I'll keep on playing with it.