Masking address bits

[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

[Demon]

Dave, here's my complete code using a 16F877 and MCP23016:

ADCON1 = 7 ' A/D off, all digital
ASM
@ DEVICE PIC16F877, HS_OSC, WDT_OFF, PWRT_ON, BOD_ON, LVP_OFF, CPD_OFF, WRT_OFF, DEBUG_OFF, PROTECT_OFF
ENDASM
define OSC 20
DEFINE I2C_SLOW 1 ' Access I2C device above 8MHz
DEFINE I2C_HOLD 1 ' Permit I2C device to hold clock line low
I2CSCL VAR PortC.3
I2CSDA VAR PortC.4
I2CCTRL con %01000000
I2CLOCB VAR BYTE
I2CWORD VAR WORD
I2CLOCB = $06 ' Set location to IODIR register
I2CWORD = %0000000000000000
i2cWRITE I2CSDA,I2CSCL,I2CCTRL,I2CLOCB,[I2CWORD]
PAUSE 12
I2CLOCB = $00 ' Set location to GPIO register
I2CWORD = %1111111111111111
i2cWRITE I2CSDA,I2CSCL,I2CCTRL,I2CLOCB,[I2CWORD]
end

It doesn't work, and it is using a constant.

I don't understand why either, I had this circuit working a few weeks ago. I'm sure I have something screwed in the code, but I don't see what it can be.

Robert

[Demon]

Just a bit more on the code above, the 1st I2CWRITE sets the pins as output, the 2nd turns them all ON.