$regfile = "2313def.dat"
$crystal = 4000000

Config Sda = Portd.5
Config Scl = Portd.4
Config I2cdelay = 10

Config Pind.6 = Output

Const Pcf8591write = &H90
Const Pcf8591read = &H91

Const Pcf8591dacconfig = &B01000000
'                            |
'                            -------- enable analog output
'                                     (used for adc as well)
Dim Dacout As Byte

Set Portd.6
Waitms 1000
Reset Portd.6
Waitms 1000

Do

  Set Portd.6
  For Dacout = 1 To 255 Step 1
    I2cstart
    I2cwbyte Pcf8591write
    I2cwbyte Pcf8591dacconfig
    I2cwbyte Dacout
    I2cstop
  Next Dacout
  Reset Portd.6
  For Dacout = 255 To 1 Step -1
    I2cstart
    I2cwbyte Pcf8591write
    I2cwbyte Pcf8591dacconfig
    I2cwbyte Dacout
    I2cstop
  Next Dacout

Loop

End