Newbie need help on What's a Microcontroller Chapter #3

azmax100

Hi all,

I am learning What's a Microcontroller Chapter #3: Digital Input-Pushbutton.

I am connecting the LED on·Pin 9 and the input (Pushbutton) on·Pin 14.

In this exercise Pin 9 will go high after the push button is press.

How to make the LED·High or doing other routine only after the Pushbutton is press 3 times?
Let say after· 3 times the button is press·Led on Pin 10 is high.

Please Help.

TQ.

Chris Savage

Hello,
·
·· Essentially you will need to update a counter variable with each press of the button and have a conditional check for when it reaches 3 then make the LED pin HIGH.· Since you’re only at Chapter #3, I would recommend completing the remaining chapters which may give you more insight on how best to accomplish this.· Take care.


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Chris Savage
Parallax Tech Support

Andy Lindsay (Parallax)

Actually, at this point, I think you've covered enough in the book to solve that problem.· It will help if you break it down into steps:

1) Declare a variable for counting.

2) Write a command inside·a DO...LOOP that adds 1 to the counting variable each time through.

3) Add a gate keeper that monitors the pushbutton, and only allows the program to move on when the button is pressed.· (Propbably a nested DO...LOOP, check the last activity in Chapter 3.)

4) Add a statement similar to this:

IF IN14 = 1 AND counter =·3 THEN

· '· Do something

ENDIF

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Andy Lindsay

Education Department
Parallax, Inc.

Post Edited (Andy Lindsay (Parallax)) : 11/2/2006 5:09:47 PM GMT

Kevin Wood

Don't forget to reset the counter to zero at some point.

azmax100

Hi all,



Thanks to all who have replied.

Finally I got the answer.

Here I attached the code.





' {$STAMP BS2}
' {$PBASIC 2.5}

counter VAR Byte

Main:
counter = 0
DO
· DO
· DEBUG ? counter
· IF IN14 =1 THEN
· counter = counter + 1
· HIGH 9
· PAUSE 500
· LOW 9
· PAUSE 500
· ENDIF
LOOP UNTIL counter = 3
· IF counter = 3 THEN
· HIGH 2
· PAUSE 1500
· LOW 2
· PAUSE 500
· ENDIF
· GOTO Main
LOOP UNTIL (IN14 =1)


Is there any other method?

Thanks again to all of you.
Respect you all.

Benoit

You've got some extra statements that won't be doing anything. You're program will be
doing the same this as this:


' {$STAMP BS2}
' {$PBASIC 2.5}

counter VAR Byte

Main:
counter = 0
DO
DEBUG ? counter
IF IN14 =1 THEN
counter = counter + 1
HIGH 9
PAUSE 500
LOW 9
PAUSE 500
ENDIF
LOOP UNTIL counter = 3

'At this point, counter will be 3
'So the IF counter=3 will ALWAYS be true
HIGH 2
PAUSE 1500
LOW 2
PAUSE 500

GOTO Main

'because the previous GOTO will Always be executed, the next loop will never be reached
'LOOP UNTIL (IN14 =1 )

AIman

One thing I learned from game programing is to remove fragments of decimals that randomly occur.

In other words instead of·
Loop until counter = 3 say Loop until counter >= 3

The reason for this is in case the computer does something like 3.01 your covered.
Doesn't happen often but it does happen.

So for what you want I would write it this way.

' {$STAMP BS2}
' {$PBASIC 2.5}

counter VAR Byte

Main:
counter = 0
DO
· DO
···· DEBUG ? counter
···· IF IN14 =1 THEN
········ HIGH 9
········ PAUSE 500
········ LOW 9
········ PAUSE 500

····· counter = counter + 1
····· ENDIF
·· LOOP UNTIL counter >= 3

This is where you need to figure out if something is going to happen only at 3 or not. If its going to happen only at 3 then write this.

·· HIGH 2
·· PAUSE 1500
·· LOW 2
·· PAUSE 500
·· if counter >= 3 then counter = 0
LOOP UNTIL (IN14 =1)

If it can happen anytime then you need to figure out when its going to happen. For example:

' {$STAMP BS2}
' {$PBASIC 2.5}

counter VAR Byte

Main:
counter = 0
DO
· DO
···· DEBUG ? counter
···· IF IN14 =1 THEN
········ HIGH 9
········ PAUSE 500
········ LOW 9
········ PAUSE 500
····· ENDIF
·· HIGH 2
·· PAUSE 1500
·· LOW 2
·· PAUSE 500···

·· counter = counter + 1
···LOOP UNTIL counter >= 3
·· if counter >= 3 then counter = 0
LOOP UNTIL (IN14 =1)

azmax100

Thanks to Aiman and couch-pilot.

You made me see the clear picture.

Since I am a newbie I need people like you to guide me.

You people are really helpfull.

Thanks.

Kevin Wood

If you want the LED to light up only after the third button press, you would set it high on counter = 3, turn it off, then reset the counter to 0 in order to count to three again.

Another way you could do it is to keep counting up with the the counter, and use the MODULUS operator to check to see if the value of counter is divisible by three. Something like this:

IF (Counter // 3) = 0 THEN LightOn

The reason you check for 0 is that modulus returns the remainder of the division operation, so 3//3 = 3/3, 1 remainder 0, 6//3 = 6/3, 2 remainder 0, 9//3 = 9/3, 3 remainder 0, etc.

This means that your IF..THEN block should run on every third button press.

Edit:

Okay, since I recommended it, I thought I would whip something up as an example. Attached is a program using SERIN to detect keyboard presses, instead of a button. You should be able to modify it for a button based on Ch3 of the WaM book. Because it uses SERIN for the input, you may need to manually connect to the debug terminal.

Post Edited (Kevin Wood) : 11/6/2006 7:10:12 AM GMT