In SX Microcontrollers, SX/B Compiler and SX-Key Tool, p.realacci wrote:

Hi,
I think I've found two problems with the SXB compiler v. 1.51.03 when used with the SX48 chip.

First problem:

The I2CSTOP function modifies the data direction register of the port associated with the SDA and SCL lines.

Example:

SDA			var ra.0
SCL			var ra.1

The function I2CSTOP SDA may randomly change the direction of the lines RA.2 and RA.3 
This happens because the compiled code loads the tris_a register with the value in __PARAM1.

Suggested workaround:
Initialize __PARAM1 with the value of the tris_a register before calling I2CSTOP 
e.g.
__param1 = tris_a
I2CSTOP SDA


Second problem:

The interrupt routine does not preserve the value of __PARAMCNT (which shares the register __PARAM5). 
As a result, if, from the interrupt,  you call a subroutine with a variable number of parameters, you can get unexpected results from your code.

Suggested workaround:
Use the following code:

INTERRUPT NOCODE
ASM		
       CLR FSR 
  	MOV __INTPARAMFSR,__PARAM1    
  	MOV __INTPARAMFSR+1,__PARAM2  
  	MOV __INTPARAMFSR+2,__PARAM3  
  	MOV __INTPARAMFSR+3,__PARAM4 
  	MOV __INTPARAMFSR+4,__PARAM5  ;
ENDASM
BANK

....your interrupt code

ASM
        CLR FSR 
  	MOV __PARAM1,__INTPARAMFSR    
  	MOV __PARAM2,__INTPARAMFSR+1  
  	MOV __PARAM3,__INTPARAMFSR+2  
  	MOV __PARAM4,__INTPARAMFSR+3  
        MOV __PARAM5,__INTPARAMFSR+4
ENDASM
RETURNINT

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