Understanding timer issues

**boroko** · - 28th March 2009, 22:59

Hi all,
trying to understand why this isn't working as it seems it should.

The Transmit: TMR1 Int handler is ~30mS and works fine. At the end of the TMR1 int, TMRO is given settings so that the first cycle through, there should be a ~190uS int cycle. After the first cycle, the TMR is reloaded so that the next passes are ~2.74 mS. For some reason, the two timer loads affect each other and changing one affects both areas in ways that I'm not understanding. I can't get any single point to adjust the two timing areas.

Code:

<font color="#000000"><b>DEFINE </b>OSC 8 
<b>DEFINE </b>DEBUG_REG PORTA 
<b>DEFINE </b>DEBUG_BIT 0
<b>DEFINE </b>DEBUG_BAUD 2400 
<b>DEFINE </b>DEBUG_MODE 0 
<b>CLEAR                                             
</b>TRISA   = %00100000      <font color="#0000FF"><i>' PortA : All outputs except RA.1 for INT_INT
</i></font>TRISB   = %01000100      <font color="#0000FF"><i>' PWM1,3,5 outputs,RB2=INT, RB0,2,3: DIO
</i></font>ADCON1  = %00001111      <font color="#0000FF"><i>'  
</i></font>T1CON   = %10000001      <font color="#0000FF"><i>' 16bit, 1:1 ps, 30 mS INT     
</i></font>RCON    = %00011111      <font color="#0000FF"><i>' NO Priority for interrupts 
</i></font>OSCCON  = %11111110      <font color="#0000FF"><i>' INTOSC, 8MHz
</i></font><b>DEBUG </b><font color="#FF0000">&quot;CSS1330-2inc&quot;</font>,13,10
<font color="#0000FF"><i>'::::::::::::
</i></font><b>INCLUDE </b><font color="#FF0000">&quot;DT_INTS-18.bas&quot;     </font><font color="#0000FF"><i>' 
</i></font><b>INCLUDE </b><font color="#FF0000">&quot;ReEnterPBP-18.bas&quot;  </font><font color="#0000FF"><i>' 
'::::::::::::

</i></font>EchoTime     <b>VAR    WORD
</b>OutPulseCnt  <b>VAR    BYTE
</b>Gain         <b>VAR    BYTE
</b>GCA          <b>VAR    </b>PORTA.1
GCB          <b>VAR    </b>PORTA.2
GCC          <b>VAR    </b>PORTA.3
GCD          <b>VAR    </b>PORTA.4
PulseOut     <b>VAR    </b>PORTB.0
EchoIn       <b>VAR    </b>PORTB.2                      
ledR         <b>VAR    </b>PORTB.3                <font color="#0000FF"><i>'
</i></font>ledG         <b>VAR    </b>PORTB.4                <font color="#0000FF"><i>'
</i></font>Prog         <b>VAR    </b>PORTB.6                <font color="#0000FF"><i>'
</i></font>CntSw     <b>VAR   WORD
</b>flag      <b>VAR   BYTE
</b>IncCnt    <b>VAR   BYTE
</b>MdCnt     <b>VAR   BYTE            
</b>TimOut    <b>VAR   BYTE
</b>Lock      <b>VAR   </b>flag.0             <font color="#0000FF"><i>' 1= locked, 0 = unlocked
        
</i></font><b>ASM
</b><font color="#008000">INT_LIST  macro    </font><font color="#0000FF"><i>; IntSource,        Label,  Type, ResetFlag?
        </i></font><font color="#008000">INT_Handler   INT2_INT,   _GetEcho,    ASM,  yes   </font><font color="#0000FF"><i>;straight I/P
        </i></font><font color="#008000">INT_Handler   TMR0_INT,  _BlankGain,  ASM,  yes
        INT_Handler   TMR1_INT,  _Transmit,   ASM,  yes
    endm
    INT_CREATE               </font><font color="#0000FF"><i>; 
</i></font><b>ENDASM
</b><font color="#008000">@    INT_ENABLE  TMR1_INT     </font><font color="#0000FF"><i>; enable Timer 1 interrupts 
'***************************************************************************
</i></font><b>GOTO </b>Start

<font color="#0000FF"><i>'*** Sub to Select MODE  *************************************
</i></font>ModeSelect:
<font color="#0000FF"><i>' first time through, need to unlock. Then can pass to others 
           </i></font><b>IF </b>MdCnt = 2 <b>THEN               </b><font color="#0000FF"><i>'1st check for unlock
              </i></font>Lock = 0
              <b>ENDIF
           IF </b>Lock = 0 <b>THEN 
              </b>ledG = 1                      <font color="#0000FF"><i>'
             </i></font><b>ELSE 
              </b>ledG = 0                                         
             <b>GOTO </b>DoneCk                    
             <b>ENDIF  
           SELECT CASE </b>MdCnt
                  <b>CASE </b>1    
                  Lock = 1                    
                  <b>DEBUG </b><font color="#FF0000">&quot;Case 1&quot;</font>,13,10
                  <b>GOTO </b>DoneCk                  
                  <b>CASE </b>2                      
                  Lock = 0                                                      
                  <b>GOTO </b>DoneCk                           
                  <b>DEBUG </b><font color="#FF0000">&quot;Case 2&quot;</font>,13,10
                  <b>CASE </b>3                       
                  <b>DEBUG </b><font color="#FF0000">&quot;Case 3&quot;</font>,13,10  
                  <b>CASE IS </b>&gt;3                       
                  <b>DEBUG </b><font color="#FF0000">&quot;Case &gt;3&quot;</font>,13,10         
                  Lock = 1                          

             <b>END SELECT     
</b>DoneCk:
           IncCnt = 0               <font color="#0000FF"><i>' reset MODE counter   
</i></font><b>RETURN
</b><font color="#0000FF"><i>'**********************
'*  END Subs
'**********************
</i></font>Start:
        Lock = 1
Mainloop:
 <b>DEBUG </b>#EchoTime,13,10 

<font color="#0000FF"><i>'code for menu selection here
       </i></font><b>GOTO </b>Mainloop
<font color="#0000FF"><i>'*********** Int handlers ***********
'---[TMR1 - interrupt handler]-------
' TMR1 = 16 bit, 1:1, 65535 - 5543(preload) ~30 mS cycle  
</i></font>Transmit:
<font color="#008000">@ INT_DISABLE   INT_INT     </font><font color="#0000FF"><i>; Disable external ints to stop Echo RX
         </i></font>TMR1H = $15             <font color="#0000FF"><i>'
         </i></font>TMR1L = $A7             <font color="#0000FF"><i>'
         </i></font>OutPulseCnt = 0         <font color="#0000FF"><i>' start new cycle
         </i></font>Gain = 0                <font color="#0000FF"><i>' 
         </i></font>PORTA = Gain            <font color="#0000FF"><i>' turn off the gain
</i></font><b>ASM 
     </b><font color="#008000">BSF</font> 	<font color="#008000">PORTB,0
     NOP     
     NOP     
     NOP
     NOP
     NOP
     NOP
     NOP
     BCF    PORTB,0
     NOP     
     NOP     
     NOP
     NOP
     NOP
     NOP
     NOP
     BSF</font> 	<font color="#008000">PORTB,0
     NOP     
     NOP     
     NOP
     NOP
     NOP
     NOP
     NOP
     BCF    PORTB,0
</font><b>ENDASM         
         </b>T0CON = %11001000       <font color="#0000FF"><i>' On, 8b, PSon, 1:1, For Blanking
         </i></font>TMR0L = 70              <font color="#0000FF"><i>' Blanking inhibit  190uS ???       
</i></font><font color="#008000">@ INT_ENABLE  TMR0_INT           </font><font color="#0000FF"><i>; Enable TMR0 to start Blanking/Gain block                
</i></font><font color="#008000">@ INT_RETURN
</font><font color="#0000FF"><i>'---[TMR0 - interrupt handler]-------------------------------
' inhibit GetEcho for 1 cycle through TMR1 with value loaded at end of transmit 
' code then change TMR1 to ramp up gain in 2.74mS steps
</i></font>BlankGain:
     OutPulseCnt = OutPulseCnt +1    <font color="#0000FF"><i>'1st pass, TMR0 Blanking set @ end of &quot;TX&quot;                                                         
       </i></font><b>SELECT CASE </b>OutPulseCnt
              <b>CASE </b>1
               T0CON = %11000101     <font color="#0000FF"><i>' On, 8b, PSon, 1:64, for Gain step
               </i></font>TMR0L = 170           <font color="#0000FF"><i>' Preload to 170 for 2.74mS INT               
</i></font><font color="#008000">@ INT_ENABLE   INT2_INT                     </font><font color="#0000FF"><i>; enable INT2 to catch Echo       
</i></font><font color="#008000">@ INT_RETURN                                </font><font color="#0000FF"><i>; go back for next INT on TMR0               
              </i></font><b>CASE </b>2
                <b>GOTO </b>MoreGain               <font color="#0000FF"><i>' 2nd pass: Gain inc 1
              </i></font><b>CASE </b>3
                <b>GOTO </b>MoreGain               <font color="#0000FF"><i>' gain inc'd to 2
              </i></font><b>CASE </b>4
                <b>GOTO </b>MoreGain               <font color="#0000FF"><i>' gain inc'd to 3
              </i></font><b>CASE </b>5
                <b>GOTO </b>MoreGain               <font color="#0000FF"><i>' gain inc'd to 4
              </i></font><b>CASE </b>6 
                <b>GOTO </b>MoreGain               <font color="#0000FF"><i>' gain inc'd to 5
              </i></font><b>CASE IS </b>&gt; 6
                <b>GOTO </b>EndGain               
        <b>END SELECT           
</b>MoreGain:
          Gain = Gain + 2     <font color="#0000FF"><i>' RA.0 is I/P, so count x2   
          </i></font>PORTA = Gain        <font color="#0000FF"><i>'sent out RA.1-RA.4, set gain amp
</i></font>SkipGain:
<font color="#008000">@ INT_RETURN

</font>EndGain:
<font color="#008000">@ INT_DISABLE  TMR0_INT     </font><font color="#0000FF"><i>; Shut-off Blanking &amp; Gain incr until next cycle 
</i></font><font color="#008000">@ INT_RETURN

</font><font color="#0000FF"><i>'---[INT - interrupt handler]-------------------------
</i></font>GetEcho:   
   EchoTime.LowByte=TMR1L
   EchoTime.HighByte=TMR1H       <font color="#0000FF"><i>' capture the counts 
</i></font><font color="#008000">@ INT_RETURN
</font><b>END
  

</b>

The DEBUG quits after the splash. I suspect it is getting blown up by the interrupt.

Thanks for looking at it.
Bo

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