In SX Microcontrollers, SX/B Compiler and SX-Key Tool, ems1965 wrote:

I have my encoders working and now I want to get the counts to my "Propeller".  If I send 2400 Baud from my Stamp2 for instance the propeller gets the data perfectly, but when I send them from my SX/B program I can't get it to work. 
 

I know it has something to do with the interrupts, but I'm not really versed on how to calculate the Clock cycles it consumes.

 

How would I calculate a baud rate that will actually send 2400?

 


[code]

DEVICE          SX28, OSCHS2, TURBO, STACKX, OPTIONX, BOR42
FREQ            50_000_000 

ID  "ENCODER"
EncPort         VAR     RA                      ' encoder port
TRIS_Enc        VAR     TRIS_A
MaxVal          CON     255
 
'encCheck VAR Byte
EncodersOld     VAR     byte                  
EncodersNew     VAR     byte                   
Encoder_A_Count VAR     byte  
Encoder_B_Count VAR     byte   
tmpB1           VAR     byte
tmpB2           VAR     Byte
tmpB3           VAR     Byte

' =========================================================================
INTERRUPT 
' =========================================================================
' Runs every 64 uS @ 4 MHz (no prescaler)
ISR_Start:
 EncodersNew = EncPort
 TmpB1 = EncodersOld XOR EncodersNew ' compare old with new
                                     ' to work out which channels have changed
 TmpB2 = TmpB1 << 1   ' make single bit that shows change on A or B phase
 TmpB1 = TmpB1 OR TmpB2
 EncodersOld = EncodersOld << 1  ' make direction bits by comparing old A with new B
 EncodersOld = EncodersOld XOR EncodersNew ' xor old A with new B
 IF TmpB1.3 = 1 THEN
     IF EncodersOld.3 = 1 THEN 
   INC Encoder_A_Count                          
     ELSE
   DEC Encoder_A_Count 
 Encoder_A_Count Min 0                           
      ENDIF
  ENDIF
' ========================================================================= 
 IF tmpB1.1 = 1 THEN                  
      IF EncodersOld.1 = 1 THEN 
     INC Encoder_B_Count                          
      ELSE
   DEC Encoder_B_Count 
 Encoder_B_Count Min 0                           
      ENDIF
   ENDIF
 EncodersOld=EncodersNew
'ISR_Exit:
  RETURNINT                                  
' =========================================================================
  PROGRAM Start NOSTARTUP

' =========================================================================
 
Start:
                              
 
  EncodersNew = EncPort
  EncodersOld = EncodersNew
  Encoder_A_Count = 0 
  Encoder_B_Count = 0 
   
  OPTION = $88                                  ' interrupt, no prescaler
Main:
Do

  Serout RC.7,T2400,Encoder_A_Count
 

LOOP

 

Thanks,

Eric

[/code]

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