PARAMCNT or PARAMn value corrupted on user defined function

slcott · 2009-12-30 00:56

I am trying to use my micromega fpu. My hardware is setup and I have established communication with the fpu. Unfortunately, I have a problem using either a subroutine or a function to write to the fpu inside of my main loop. It seems that either my __PARAMn values or __PARAMCNT gets corrupted somehow because my sx fpu function leaves out the ARG and only passes an OPCODE to the FPU. Has anyone had experience with user defined functions going haywire like this.

Post Edited (slcott) : 12/30/2009 1:44:59 AM GMT

Bean · 2009-12-30 12:13

SX/B code will re-use the _PARAMx variables.
It looks like you ARE copying them to other variables, so it should work.
If you could post the whole program we could help more.

Bean.

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slcott · 2010-01-02 02:24

i tried converting all the subroutines to functions instead with no effect. i also tried calling Fpu_SPI_Write only which works on a single argument at a time which serves as a workaround, but I would like full use of my fpu.SXB functions for ease of further development. When I call Fpu_Write with 2 or more arguments, the 2nd and following arguments are reported by my fpu as 0. I think the prob is in the microcontroller.

Zoot · 2010-01-02 16:55

It's not the microcontroller, trust us. There may be a number of problems with your code that are clobbering your param registers. I also found several logic errors that would certainly lead to weird results, for example:

FUNC Fpu_Write
  tmp1 = __PARAM1
  if __PARAMCNT = 1 then
    Fpu_SPI_Write tmp1
  else
    tmpCnt = __PARAMCNT
    tmp2 = __PARAM2
    tmp3 = __PARAM3
    tmp4 = __PARAM4
    Fpu_SPI_Write tmp1
    Fpu_SPI_Write tmp2
    if tmpcnt < 3 then Fpu_Write2
    Fpu_SPI_Write tmp3
    if tmpcnt < 4 then Fpu_Write2
    Fpu_SPI_Write tmp4
  endif
  Fpu_Write2
  return
ENDFUNC

FUNC Fpu_Write2
  return
ENDFUNC

In the above, the line "if tmpcnt < 3 then FPU_Write2" will NOT call the function, it will GOTO the function, then return, without executing following code. You may want to break some of your code into very small testable piece and make sure each piece is OK before working the pieces into a larger program.

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__PARAMCNT or __PARAMn value corrupted on user defined function

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PARAMCNT or PARAMn value corrupted on user defined function