Pin condition check to change state in a State Machine

[G. C.]

Hi there,

I am preparing a little program for a new project in wich I use a simple program architecture with a State Machine.

Checking the pressure of a button to ground on a pin, doing it in the main Do-Loop before entering the Select Case block of the State Machine, I can cycle trough 1 to 5 states without problem..

But if I want to check the pin condition WHITIN one of the states, in order to move from one state to another, the button pressure gets ignored..

I made several tests, but I am still stuck because of this at the very beginning of the development.

Any suggestion? Thanks!

[Anobium]

I think you have an error in the display of the state.

Try

Do   

    ' 1. Handle Button Inputs & State Transitions independently 
    Select Case stato

        case 1  'Attesa input Utente
            Riga1 = " Press Start to "
            Riga2 = " make a Measure "

            if Start_Btn = 0 then       
                wait 100 mS 'debounce
                if Start_Btn = 0 then        
                    Wait Until Start_Btn = 1
                    stato = 2
                end If               
            end if

        case 2      
            Riga1 = "This is State 2"
            Riga2 = "press to go 3rd!"

            ' Add your button check here to advance to state 3!
            if Start_Btn = 0 then       
                wait 100 mS
                if Start_Btn = 0 then        
                    Wait Until Start_Btn = 1
                    stato = 3
                end If               
            end if

        case 3  
            Riga1 = "This is State 3"
            Riga2 = "press to go 4th!"

            if Start_Btn = 0 then       
                wait 100 mS
                if Start_Btn = 0 then        
                    Wait Until Start_Btn = 1
                    stato = 4
                end If               
            end if

        case 4
            Riga1 = "This is State 4"
            Riga2 = "press to 1st!" // or 5

            if Start_Btn = 0 then       
                wait 100 mS
                if Start_Btn = 0 then        
                    Wait Until Start_Btn = 1
                    stato = 1 ' Cycle back or go to 5
                end If               
            end if

        case 5   
            Riga1 = "Error ! Shutdown"
            Riga2 = "System & Restart"

            StartTimer 1    
            if Timer_Steps = 15 Then 
                Led_diagnostico = Not Led_diagnostico    
                Timer_Steps = 0                         
                ClearTimer 1
            end If

    end select


    ' 2. Display refresh managed strictly on state change
    if stato_precedente <> stato then
        cls
        Print Riga1
        Locate 1,0
        Print Riga2
        stato_precedente = stato    
    End if

    ' 3. Diagnostic LED cleanup
    if stato <> 5 then Led_diagnostico = 0

Loop

[G. C.]

Thanks for your answer, Evan..

However, I can't see the difference in respect to my code. It does'nt matter (for the moment) to add more button checks into the other states. The cycling was made only to begin the development, during the final version states may change on different criteria..

The problem is that this block here is completely ignored:

(whitin State=1)

if Start_Btn = 0 then
wait 100 mS 'debounce
if Start_Btn = 0 then
Wait Until Start_Btn = 1
stato = 2
end If
end if

I found an error of mine in not disabling the analog inputs on port A that I tought could be the problem, so I changed my previous line (acting only on B port) as follows:
from:
ADCON1 = 0x0F
to:
ANSEL = 0
ANSELH = 0 ' should disable analog on both portA & portB

Hoping this was the issue, but the problem is the same. Test on button made outside the Select Case block works, inside one of the Case x does not..

Can't really thing of anything else happening.. ?!?
Should the "Case Else" statement addition mandatory to have the Select Case working?

updated file attached for reference

[G. C.]

Might it be possible that multiple if/then blocks nested whitin a Do-loop that contains a Select Case etc.. creates some reentrance prolems with this small uCtr?

[Anobium]

The ports are disabled automatically. so that is is not the issue.

This is logic code not the state of the port. I have refactored so the logic makes sense to me.

It works here.

Evan

' =====================================================================
' CONFIGURAZIONE DEL CHIP E DELLE PERIFERICHE
' =====================================================================
#Chip 16F886, 8       ' Imposta il microcontrollore a 8 MHz
#config FOSC = HS       ' utilizza il quarzo esterno

' =====================================================================
' CONFIGURAZIONE DEL DISPLAY LCD (Modalit� 4-bit)
' =====================================================================
#Define LCD_IO 4
                                    'linee valide per Protoboard, cambiare in
#Define LCD_Enable PORTA.0          '#Define LCD_Enable PORTA.2   nel PCB finale
#Define LCD_RW PORTA.1  
#Define LCD_RS PORTA.2              '#Define LCD_RS PORTA.0   nel PCB finale

#Define LCD_DB4 PORTB.4
#Define LCD_DB5 PORTB.5
#Define LCD_DB6 PORTB.6
#Define LCD_DB7 PORTB.7


' =====================================================================
' CONFIGURAZIONE Altre Costanti
' =====================================================================
#Define On = 1              'costanti per chiarire i valori assegnati ai flag, Pin I/O e variabili
#Define Off = 0

#Define Start_Btn PORTA.4           'Pulsante Utente per avviare le misure
#Define Led_diagnostico PORTC.3     'Uscita led lampeggiante per Diagnostica Programma


' =====================================================================
' DICHIARAZIONE DELLE VARIABILI
' =====================================================================

Dim stato as Byte               'identificatore dello stato macchina
Dim stato_precedente as Byte    'per decidere se effettuare refresh display senza sfarfallio 
Dim Timer_Steps as Byte         'numero di overflows del Timer1
Dim Riga1 as string (16)        'contiene buffer 1a riga display
Dim Riga2 as string (16)        'contiene buffer 2a riga display
Dim debug = 1

' =====================================================================
' CONFIGURAZIONE HARDWARE
' =====================================================================
Dir PORTB.0 In              ' RB0 (INT0) come ingresso su cui misurare l'impulso
ADCON1 = 0x0F               ' Disabilita i convertitori A/D su PORTB

Dir PORTC.3 out             ' uscita per Led diagnostico
Dir PortA.4 in              ' pulsante Utente


' Configura il Timer1 (Incremento ogni 1/2 microsecondo)
InitTimer1 Osc, PS1_1
StopTimer 1
ClearTimer 1


' =====================================================================
' CONFIGURAZIONE INTERRUPT
' =====================================================================

'gestione interrupt per overflow Timer1
On interrupt Timer1Overflow call Incrementa_Timer_Steps


Print "Started"

' =====================================================================
' Avvio Programma, eseguito solo all'accensione
' =====================================================================

'inizializza stati
stato = 1
stato_precedente = 0

' =====================================================================
' CICLO PRINCIPALE della macchina a stati
' =====================================================================

Do   

 '***** This commented block down here works when a pushbutton is pressed to ground on a 10K Ohm pull-upped PORTA.4
 ' and cycles to the various states without problems

/*
    'se premo il pulsante passa allo stato successivo
                if Start_Btn = 0 then               
                    wait 100 mS 'debounce

                    if Start_Btn = 0 then         
                        'Attesa rilascio pulsante per evitare passaggi di stato multipli
                        Wait Until Start_Btn = 1
                        stato ++
                    end If

                    if stato= 6 then stato = 1    

                end if

*/

        Locate 2,0
        Print stato
        Locate 3,0
        Print leftpad(Str(debug), 3, " ")
        debug++

    Select Case   Stato  

        case 1  'Attesa input Utente per avviare una Misura    

                Riga1 = " Press Start to "
                Riga2 = " make a Measure "

                '************ The same condition checked here whitin one state gets ignored!
                '*** Hardware is ok, using the condition on the above mentioned block
                '*** outside the states, everything goeas as expected.. Why?? 
                ShowLCD
                waitforbtn
                stato = 2

        case 2      

                Riga1 = "This is State 2"
                Riga2 = "press to go 3rd!"
                stato_precedente = 0
                ShowLCD
                waitforbtn
                stato = 3


                'later on more code

        case 3  'in questo stato si determina la durata del tempo in microsecondi

                Riga1 = "This is State 3"
                Riga2 = "press to go 4th!"
                stato_precedente = 0
                ShowLCD
                waitforbtn
                stato = 4


                'later on more code

        case 4

                Riga1 = "This is State 4"
                Riga2 = "press to 5th!"
                stato_precedente = 0
                ShowLCD
                waitforbtn
                stato = 5


                'later on more code


        case 5   'solo lampeggio Led su porta C3 , ad uso diagnostico programma

                'segnala errore e fa lampeggiare Led
                Riga1 = "Error ! Shutdown"
                Riga2 = "System & Restart"
                stato_precedente = 0
                ShowLCD
                waitforbtn



                StartTimer 1    'avvia il timer. Se gi� attivo, non viene resettato  il conteggio

                if Timer_Steps = 15 Then 

                Led_diagnostico= Not Led_diagnostico    'inverto polarit�
                Timer_Steps = 0                         'riazzero timer
                ClearTimer 1

                'se ci sono stati 15 Overflows del Timer1, il
                'led commuta ogni 0,49152 secondi - circa 2.032 Hz

                end If


    end select




    'Per evitare che resti acceso il led blinker se non necessario
    if stato <> 5 then Led_diagnostico = 0

Loop 

Sub ShowLCD
    'gestione aggiornamento display
    if stato_precedente <> stato then

        cls
        Print Riga1
        Locate 1,0
        Print Riga2
        stato_precedente = stato    'necessario per evitare 'flickering' del dispaly
        Wait 100 ms

    End if
End Sub


' =====================================================================
' Gestione Interrupt da Timer1 Overflow
' =====================================================================
Sub Incrementa_Timer_Steps              

    Timer_Steps++ ' Timer_Steps +1

End Sub

Sub WaitforBtn
                'se premo il pulsante passa allo stato successivo
                'di gestione interrupt impulso  
                if Start_Btn = 0 then               
                    wait 100 mS 'debounce

                    if Start_Btn = 0 then         
                        'Attesa rilascio pulsante per evitare passaggi di stato multipli
                        Wait Until Start_Btn = 1
                    end If                  
                end if
End Sub

[G. C.]

Thanks for yr answer.. I made additional tests.
Your code for some reasons gives me errors, starting as soon as the row "Dim debug = 1".. And others..
I reduced my code to the bare minum of two states, and in this case it works( see test1.gcb attached). But as soon as more "case is" block get added, I find troubles.
Therefore I decided to abandon the Select Case approach e moved to a series of "if state is.." and my code works fine.
Finally, I improved the display refresh method and also the pushbutton detection, making it a function callable from any state - and it works ok. See test2.gcb).
I am not sure, but perhaps there is something stange in the Select Case -Case is structure.

Thanks for yr help given, I appreciated it.

[Anobium]

There was/is nothing wrong with Case. :-) This is logic issue.

You have a method that works. And, this is a good result for you.

[Anobium]

Good news. All working.

I am using the new compiler and you can now assign a value to a variable when you DIMension it.

[G. C.]

I apologize if I cast a doubt on the Select Case correct working..
I persisted a while with some tests and found my error being in the need to prepare the new text and display refresh flag at the moment of leaving the present state and moving to the following one..
Now the sequence is correct, and the flow and readability of the program been improved with Select Case, a subroutine for LCD refresh and a Function for the button pressed test. Attached a working version of this prime stage. Sorry having bothered.

Answering yr last post:
So, there is an updated version of the compiler coming, great news. Is there any thinking about a debugger (even a limited one) that might permit to pause the program and look at the variables/registers etc on fly? That would makemuch speedier the development with GC Basic.
Thanks for the great work, and regards.

[Anobium]

No problem with CASE. I am just grumpy at the moment. :-)

And, no problem with you asking. Sometimes just sharing helps. :-)

The new code looks good. :-)

---

There is a new version on the toolchain and compiler. We are close to a release.

There is a new debugger. See the picture. Yes, your code in the GCODE Debuuger!

Soon!

Evan