'PCF8574 stepper example
'http://aquaticus.info


'uncomment for atmega16
$regfile = "m16def.dat"

'uncomment for atmega32
'$regfile = "m32def.dat"

$crystal = 14745600

'hardware TWI library
$lib "I2C_TWI.LBX"

'TWI clock (100kHz)
Config Twi = 100000


Dim B As Byte
Dim I As Integer
Dim Pcf8574 As Byte
Dim Steptab(8) As Byte
Dim Steps As Byte
Dim Step_mode As Byte

'Address of PCF8574

'JP1: SHORT 1-2
Pcf8574 = &H40

'JP1: SHORT 2-3
'Pcf8574 = &H42

'set 1 for half-step, 0 for full-step mode
Step_mode = 0

'Diagnostic messages on DB1
Open "comc.5:2400,8,n,1" For Output As #1

Print #1 , "PCF8574 TEST. I2C ADDRESS: " ; Hex(pcf8574) ; " hex"
Print #1 , "STEPPER ON X3 ";

If Step_mode <> 0 Then
   'half step
   Print #1 , "HALF STEP MODE"
   Steps = 8
   Restore Half_step
Else
   'full step
   Print #1 , "FULL STEP MODE"
   Steps = 4
   Restore Full_step
End If


'initialize step table
For I = 1 To Steps
   Read B
   Steptab(i) = B
Next I

'Infinite loop
Do
   For I = 1 To Steps
      'flash optional LED on SL9
      Toggle Porta.2

      'send data to pcf8574
      I2csend Pcf8574 , Steptab(i)

      'this value affects the speed of rotation.
      Waitms 50
  Next I
Loop

Full_step:
Data &B10000000 , &B01000000 , &B00100000 , &B00010000

Half_step:
Data &B10000000 , &B11000000 , &B01000000 , &B01100000 , &B00100000 , &B00110000 , &B00010000 , &B10010000