Masking address bits

[Dave]

mister_e, I don't think the statement:
I2cWRITE blah,blah2,IoExpander[Loop],[SteakBledindePatate] will work as the variable "IoExpander" is not a constant but rather an array. I have tried using this syntax in the past with no success.

Dave Purola,
N8NTA

[mister_e]

mmm, interesting, never tried it before... Thanks Dave!

Anybody else tried that before and got bad results with this ?

anyways, here's an easy workaround.

IOExpander var byte[7]
WichIOExpander var byte
IOExpander[0]=%11110000
IOExpander[1]=%11110001
IOExpander[2]=%11110010
IOExpander[3]=%11110011
IOExpander[4]=%11110100
IOExpander[5]=%11110101
IOExpander[6]=%11110110

For Loop = 0 to 6
    WichIOExpander=IoExpander[Loop]
    I2cWRITE blah,blah2,WichIOExpander,[SteakBledindePatate]
    pause 5
    next

OR

IOExpander=%11110110

For Loop = 0 to 6
    I2cWRITE blah,blah2,(IOExpander+Loop),[SteakBledindePatate]
    pause 5
    next

And if it doesn't work..

WichIOExpander var byte
IOExpander=%11110110

For Loop = 0 to 6
    WichIOExpander=IOExpander+Loop
    I2cWRITE blah,blah2,WichIOExpander,[SteakBledindePatate]
    pause 5
    next

Sorry, i can't check any of the above where i am right now.

[Dave]

mister_e, That is the exact work around I tried in the past with no success. It is still using a variable instead of a constant. I do wish any upcomming versions of PBP will fix this problem. I have 6 PCF8574's that I have addressed in succession and thought I would use 1 address and then just offset it in a formula to access the others. The problem is it only accesses the base address. I had to write seprate statements to access the others. I just thought you and others would like to know.. If any other people on this forum have found a workaround I'm all ears....Chears for now....

Dave Purola,
N8NTA

[Demon]

Dave, are you serious? You can't use a variable for that field?

I'm up the creek also then, my project relies heavily on MCP23016 ICs and controlling them within a loop. One easy alternative would be a bunch of IFs:

IF loop = 0 THEN I2cWRITE blah,blah2,Constant0,[SteakBledindePatate]
IF loop = 1 THEN I2cWRITE blah,blah2,Constant1,[SteakBledindePatate]
IF loop = 2 THEN I2cWRITE blah,blah2,Constant2,[SteakBledindePatate]
IF loop = 3 THEN I2cWRITE blah,blah2,Constant3,[SteakBledindePatate]
IF loop = 4 THEN I2cWRITE blah,blah2,Constant4,[SteakBledindePatate]
IF loop = 5 THEN I2cWRITE blah,blah2,Constant5,[SteakBledindePatate]
IF loop = 6 THEN I2cWRITE blah,blah2,Constant6,[SteakBledindePatate]
IF loop = 7 THEN I2cWRITE blah,blah2,Constant7,[SteakBledindePatate]

But I'm not very keen on this idea.

Robert

[Dave]

Demon, This is the code I assumed would work:

UNIT0 CON %01110000 'U5's CONTROL BYTE (PCF8574A) I/O EXPANDER

************************************************** ********
R_WI2CSW:'READ DIGITAL INPUTS FROM or WRITE DIGITAL OUTPUTS TO PCF8574'S
************************************************** ********
SWCNTR = 0
WHILE SWCNTR < 6
CONTROL = UNIT0 | (SWCNTR << 1)
IF READ_WRITE = 0 THEN 'READ INPUT STATUS FROM PCF8574'S
I2CREAD SDA,SCL,CONTROL,[SWITCHES(SWCNTR)]
ELSE 'WRITE OUTPUT STATE TO PCF8574'S
I2CWRITE SDA,SCL,CONTROL,[OUTPUTS(SWCNTR)]
ENDIF
SWCNTR = SWCNTR + 1
WEND
RETURN

But it didn't work as explained in my earlyer post. This is what I had to do instead:

UNIT0 CON %01110000 'U5's CONTROL BYTE (PCF8574A) I/O EXPANDER
UNIT1 CON %01110010 'U6's CONTROL BYTE (PCF8574A) I/O EXPANDER
UNIT2 CON %01110100 'U7's CONTROL BYTE (PCF8574A) I/O EXPANDER
UNIT3 CON %01110110 'U11's CONTROL BYTE (PCF8574A) I/O EXPANDER
UNIT4 CON %01111000 'U12's CONTROL BYTE (PCF8574A) I/O EXPANDER
UNIT5 CON %01111010 'U13's CONTROL BYTE (PCF8574A) I/O EXPANDER


************************************************** ********
R_WI2CS:'READ DIGITAL INPUTS FROM or WRITE DIGITAL OUTPUTS TO PCF8574'S
************************************************** ********
IF READ_WRITE = 0 THEN 'READ INPUT STATUS FROM PCF8574'S
I2CREAD SDA,SCL,UNIT0,[SWITCHES(0)]
I2CREAD SDA,SCL,UNIT1,[SWITCHES(1)]
I2CREAD SDA,SCL,UNIT2,[SWITCHES(2)]
I2CREAD SDA,SCL,UNIT3,[SWITCHES(3)]
I2CREAD SDA,SCL,UNIT4,[SWITCHES(4)]
I2CREAD SDA,SCL,UNIT5,[SWITCHES(5)]
ELSE
I2CWRITE SDA,SCL,UNIT0,[OUTPUTS(0)]
I2CWRITE SDA,SCL,UNIT1,[OUTPUTS(1)]
I2CWRITE SDA,SCL,UNIT2,[OUTPUTS(2)]
I2CWRITE SDA,SCL,UNIT3,[OUTPUTS(3)]
I2CWRITE SDA,SCL,UNIT4,[OUTPUTS(4)]
I2CWRITE SDA,SCL,UNIT5,[OUTPUTS(5)]
ENDIF
RETURN

Now very elegant......

Dave Purola,
N8NTA

[mister_e]

I'll have an eye on this once back in town. Interesting...

Is the same thing happen with Lookup too?

WichIOExpander var byte

For Loop = 0 to 6
    Lookup WichIOExpander,[%11110000,%11110001,%11110010,%11110011,_
                           %11110100,%11110101,%11110110]
    I2cWRITE blah,blah2,WichIOExpander,[SteakBledindePatate]
    pause 5
    next

About now? Just curious

[Demon]

Steve, I'm not set up to test right now.

Dave, are you sure you used a BYTE?

I reread the manual and there is nothing for I2CREAD that says CONTROL byte must be a constant.

Robert