Need help creating a sub and transferring parameters

eagletalontim

I finally got my serial LCD in and I am messing around with some of my own functions to use it. Right now, I am attempting to create a sub that I can pass 3 parameters to it. The first parameter will be a string or just one character. The second parameter will be a number 0 or 1 and the third parameter will be a number 1 through 16. I have no idea what to set the SUB to : my_sub SUB 3? Would each parameter be _WPARAM12 and/or _PARAM#?

eagletalontim

ok, nevermind. I got it [noparse]:)[/noparse]

Bean

Well for anyone else that wonders how to do it...

If the first parameter is a character, then __PARAMCNT will be 3, the character will be in __PARAM1, the 0 or 1 will be in __PARAM2 and the 1-16 will be in __PARAM3.

If the first parameter is a string, then __PARAMCNT will be 4, the string address will be in __WPARAM12, the 0 or 1 will be in __PARAM3, and the 1-16 will be in __PARAM4.

You would define the subroutine as

LCDOut SUB 3,4

SUB LCDOut
· IF __PARAMCNT = 3 THEN
··· ' Handle character sent
· ELSE
··· ' Handle string sent
· ENDIF
ENDSUB

Bean.

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·

Shawn Lowe

Thanks for explaining further Bean!

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Shawn Lowe


When all else fails.....procrastinate!

eagletalontim

I ran into another problem and it is confusing me yet again....

I have 2 chips that are synced together. One sends data, the other receives. I have a sub called SEND_BYTE that should be used as SEND_BYTE byte1, byte2, byte3. When I use the sub, only byte3 is sent. The other 2 are not sent for some reason. If I simply put the SEROUT commands in the Main, they all send perfectly. I need help figuring what to set the SUB as and if the PARAM values are correct.

Here is my code :

SEND_BYTE    SUB    3

Start:
  PLP_A = %0001                    ' pull up unused pins
  PLP_B = %00000000
  PLP_C = %00000000
  temp3 = 255
  temp1 = 13
  temp2 = 27
Main:
  DEC temp3
  SEND_BYTE temp1, temp2, temp3
  wait 2000
  GOTO Main

........

SEND_BYTE:
  SEROUT RX, Baud, SYNC
  SEROUT RX, Baud, __PARAM1
  SEROUT RX, Baud, __PARAM2
  SEROUT RX, Baud, __PARAM3
  RETURN

Thanks for the help in advance!

Post Edited (eagletalontim) : 1/11/2009 3:08:50 PM GMT

Zoot

Most of the "high-level" SX/B instructions use the __PARAM variables for their own "internal workings". In other words, commands like PULSOUT, SEROUT, SERIN, division, multiplication use __PARAM1, __PARAM2 etc. If you closely examine the list output, you can see which are used when, but if you are unsure, PRESUME that the values in the PARAM variables will get nuked and will change after instructions like SEROUT.

The solution is to store params passed to a sub in temp variables so they are not destroyed before you have a chance to use them. Most of the SX/B code posted by JonnyMac and others follow this structure, e.g.

SEND_BYTE:
  tmpB1 = __PARAM1
  tmpB2 = __PARAM2
  tmpB3 = __PARAM3
  SEROUT RX, Baud, SYNC
  SEROUT RX, Baud, tmpB1
  SEROUT RX, Baud, tmpB2
  SEROUT RX, Baud, tmpB3
  RETURN

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eagletalontim

My mistake... i found that temp1 and temp2 were changed in another sub.

EDIT...
I did change the params to be loaded into variables like you suggested. it works perfect now [noparse]:)[/noparse]