Need some help!!

Comments

• kwinn Posts: 8,697

  2019-08-28 14:59

  How is the button connected to the microcontroller?
• Genetix Posts: 1,742

  2019-08-28 18:27

  silence00,
  
  Look at page 79 of "What's a Microcontroller?".
  https://www.parallax.com/sites/default/files/downloads/28123-Whats-a-Micro-v3.0.pdf
• Tracy Allen Posts: 6,656

  2019-08-28 19:29

  ' suppose button is on p0, with pullup resistor to Vdd
  ' state machine logic, can be part of a loop executing other tasks.
  oldstate VAR bit
  newstate VAR bit
  activestate VAR bit
  
  oldstate = in0    ' initialize state
  DO
     newstate = in0
     activestate = newstate ^ oldstate & newstate ' active when button is released to high level
     oldstate = newstate
     IF activestate THEN DEBUG "buttonup",CR
     ' do other tasks
  LOOP
  

  
  There are many ways to scan buttons depending on the goal. There is also the PBASIC BUTTON command, but that is total overkill unless you want the repeat function.
  
  A reference:
  http://emesystems.com/OLDSITE/BS2fsm.htm#counter
  
• xpacesix Posts: 1

  2020-10-11 20:00 edited 2020-10-13 04:09

  Hi, i'm beginner , therefor i can't understand some simple thing like push button Counter. my problem: in need to write a simple program, which one, counting the push button,wenn pressed and save it in one register for later. for example: if button pressed one time, led1 on. led 2&3 off. if button pressed two time, just led 2 on. led1&3 off if button pressed 3 time, just led3 on, led1&2 off and wenn pressed a gain, repeat it same. i founded this code:
  

  int main() { int count=0; int old_pb=0; int new_pb; pb.mode(PullUp); wait(.001); while(1) { new_pb = pb; if ((new_pb==0) && (old_pb==1)) count++; myled4 = count & 0x01; myled3 = (count & 0x02)>>1; myled2 = (count & 0x04)>>2; myled = (count & 0x08)>>3; old_pb = new_pb;
  

  
  
• Mike Green Posts: 23,101

  2020-10-11 21:47 edited 2020-10-13 04:10

  You need what's called a "Finite State Machine". There's a very thorough article in the Wikipedia on this (<https://en.wikipedia.org/wiki/Finite-state_machine>). Each state becomes a loop with a specific label. The program does a GOTO another state when a button is pressed. You might have something like this:

  state000:
  led1 = 0 ' Set up LEDs for this "idle" state
  led2 = 0
  led3 = 0
  if button1 = 1 then goto state001 ' If button pushed, go to next state
  goto state000 ' otherwise, stay in this state
  state001:
  if button1 = 0 then goto state002 ' Make sure button is released
  goto state001 ' Stay in this state until button released
  state002:
  led1 = 1 ' Set up LEDs for this state's action
  led2 = 0
  led3 = 0
  if button1 = 1 then goto state003 ' If button pushed, go to next state
  goto state002
  state003:
  if button1 = 0 then goto state004 ' Make sure button is released
  goto state003
  state004:
  led1 = 0 ' Set up LEDs for this state's action
  led2 = 1
  led3 = 0
  if button1 = 1 then goto state005 ' If button pushed, go to next state
  goto state004
  

  
  You can continue this for as many states as you need. You could have a second button that takes you back to state000 or whatever you want.
• frank freedman Posts: 1,975

  2020-10-22 03:56

  Happened on this thread by accident, but a good book on this (if it is still in print) is "Digital Logic and State Machine Design" by David J. Comer. If you are a student or interested in this topic, it is an excellent resource. Lots of ways to get it, but don't bother with amazon new, we can put up with a lot of flaws in used $8.00USD vs. $200USD new. Also recommend the paperback if you can find it "Realtime Programming: Neglected Topics" by Caxton C. Foster. Both can be found on google books and other sources.
  
• Wuerfel_21 Posts: 4,461

  2020-10-22 18:59

  frank freedman wrote: »

  Happened on this thread by accident, but a good book on this (if it is still in print) is "Digital Logic and State Machine Design" by David J. Comer. If you are a student or interested in this topic, it is an excellent resource. Lots of ways to get it, but don't bother with amazon new, we can put up with a lot of flaws in used $8.00USD vs. $200USD new. Also recommend the paperback if you can find it "Realtime Programming: Neglected Topics" by Caxton C. Foster. Both can be found on google books and other sources.

  
  You can also digitally borrow many books for free from openlibrary.org. I've had luck there with older technical books.