Serin sx28

sumguy16

I need two pass to variables to an SX28 via SERIN. I'm using a bluetooth module so I only have one RX. The variables I know can only be one byte at a time so I can have the value of the variables be between 0 and 255 , not a problem. I just need a solution that the SX28 will know the difference between the two variables. Any ideas?

Thanks,
Adam

Jon Williams

That's actually quite simple: create a subroutine to do your SERIN and then call it twice.· The SX28 runs fast enough that it will be able to deal with the variables in between transmissions.· As of version 1.3 you can use subroutines like functions in other languages:

· myVar1 = GETBYTE
· myVar2 = GETBYTE

Here's the code for the GETBYTE subroutine:

GETBYTE:
· SERIN Sio, Baud, temp1
· RETURN temp1

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Jon Williams
Applications Engineer, Parallax

KenM

Jon or anybody,
I am not familiar with "use subroutines like functions"

Is the end result that the subroutine is called and temp1 is returned to myVar1 and the same with myVar2?
Thank you.

 
  myVar1 = GETBYTE
  myVar2 = GETBYTE
 
GETBYTE:
  SERIN Sio, Baud, temp1
  RETURN temp1

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Ken

Jon Williams

As of 1.3 SX/B can pass values back via W. When used like the example above, W gets loaded with temp1 at the end of the subroutine and then goes back to the caller where W is moved to the target variable. I thought I had made a big deal about this feature when it was released... clearly nobody pays attention to me -- unless I make a mistake!

Here's the SX/B compiler output of a little test that shows the mechanics:

Start:                           ;Start:
  MOV myBits,#$AA                ;  myBits = $AA  
  MOV __PARAM1,myBits            ;  myBits = INVERTBITS myBits
  CALL @__INVERTBITS            
  MOV myBits,W                  
  JMP $                          ;  END

INVERTBITS:                      ;INVERTBITS:
  MOV temp1,__PARAM1             ;  temp1 = __PARAM1
  MOV W,/temp1                   ;  temp1 = ~temp1
  MOV temp1,W                   
  MOV W,temp1                    ;  RETURN temp1
  RETP 

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Jon Williams
Applications Engineer, Parallax

Post Edited (Jon Williams (Parallax)) : 7/12/2005 2:59:04 PM GMT