beginner help - Snippet of code for button press

plingboot

Hi all,
I just wondered whether anyone had a snippet of code they could post to help me get started with the SUI buttons on my BotBoard2/BS2p please. The button/led's are on pins 12, 13 and 14.

At this moment, i just want to get to grips with making it work - ie playing a sound on a button push or showing a message in the debug window.

I guess i'd like to be able to have a version which detected which button was is being pushed at start-up too?

Thanks in advance.

NR1X

http://www.parallax.com/Portals/0/Downloads/docs/books/edu/Wamv2_2.pdf

plingboot

Thanks for the link,
Just tried the simple programme on p78 (with my botboard 2) but instead of the debug showing 0 while the button is up and 1 when it's down, i'm getting the opposite. ie: 1 and when i press i get 0

Cold anyone point out the error of my ways?

' {$STAMP BS2p}
' {$PBASIC 2.5}

DO 
DEBUG ? IN12
PAUSE 250 
LOOP

NR1X

the differance between active high and active low is why you have differant results.. if you have 0 without pushing button then you have active high. (high signal when button is pressed)
if you have 1 without pressing button then you have active low.(low signal when button is pressed).. if you haven't gone through the whats a microcontroller text, it is highly recommended.. you will learn alot about what the stamp can do and how to make it do what you want..

GICU812

Yea, it sounds like you have a high pullup on the pin, and the switch is connected to ground. If you pull the pin low, and connect the switch to +5v then you will get 0 when waiting and 1 when pressing.
Some other useful button code

Wait for button press, then run code.

do while in12 = 0 ' if in12 is low, then loop, if in 12 is high, exit loop
loop

your code here


Polling buttons

do
if in12=1 then gosub button1
if in13=1 then gosub button2
if in14=1 then gosub button3
loop

button1:
debug "Button 1 pressed"
return

button2:
debug ... you get the idea

Also, you can refrence the pins with names

Button1 PIN 12

do

if Button1 = 1 then debug "Button 1 is Pressed"
if in12 = 1 then debug "This also shows button one is pressed

loop

All of the above was assuming you were working with a high signal when the button was pressed. If you continue working with a low signal, just invert all the 0's to 1' and 1's to 0's


That should get you playing.

GICU812

oh and is may be useful to wait for the button to be released before moving on with code, otherwise if its fast enough, it will run the code several times per button push

do
if in12=1 then gosub button1
loop


button1:
do while in12=1 'this will hold the program until you release button 1
loop
now put your code

plingboot

thanks for the reply.

i'm using a lynxmotion botboard2. the buttons are built-in to the board - 3 of them on pins 12, 13, 14. They are enabled with 3 jumpers. I'm therefore not sure what needs to be done to change to a high signal - or whether it's necessary.

the brief info on using the buttons (in the instruction pdf) says:

The 3 LEDs and Pushbuttons use only 3 I/O lines to make a simple user interface for your program.
By making the I/O line a low output the LED can be turned on. By briefly making the I/O line an input the I/O line cane be read to see if a button is being pressed. However, do not make the I/O line a high output and press a button, as amage to the I/O pin can occur.

NR1X

sounds like the buttons are hardwired as active high..