'**********************************************************************
' Application Note: Using the MCP23016 I/O expander
'-----------------------------------------------------
'
' Program-ID.: AN245 MCP23016.bas.
' Date...... : 22 / 05 / 2005
' Description: Example program for I2C MCP23016 I/O expander
' write and read routines.
'
' Author : Roland van leusden (sayang@zonnet.nl).
'
' Setup for the AT90S2313 using portd.6 for SDA and Portd.5 for SCL.
' (Futurlec ET-JRAVR board)
' See AN245 page 9 from Microchip for MCP23016 shematic.
'
' This program provides an example for writing to and reading from
' an I2C MCP23016 device wired for device 0 (AO,A1 and A2 all pulled
' to Gnd).
'
'
'**********************************************************************
$regfile = "2313def.dat" ' Change for your AVR.
$crystal = 4000000 ' 4 MHz Crystal.
$baud = 19200 ' Output at 19200 baud.

'**********************************************************************
'** Set up Data Direction Registers and ports - Do this before defining I2C pins!
'**********************************************************************
' Port B
Portb = &B0000_0000 ' Set All Port Pins Low
Ddrb = &B1111_1111  ' Set Unused Pins As Outputs.
' Port D
Portd = &B0000_0000 ' All low - with push-pull output
Ddrd = &B1111_1111 ' with internal pullups.

'**********************************************************************
'** Define and initialize I2C pins **
'**********************************************************************
Config Sda = Portd.6  ' I2C Data.
Config Scl = Portd.5 ' I2C Clock.

'**********************************************************************

'**********************************************************************
'
'** Declare subroutines **
'**********************************************************************
'
' This subroutine writes data to the I2C MCP23016.
'
Declare Sub I2c_mcp23016_write(byval Cmd As Byte , Byval Lsb As Byte , Byval Msb As Byte)
'
' This subroutine reads data from the I2C MCP23016.
'
Declare Sub I2c_mcp23016_read

'**********************************************************************
'** Define working variables and constants  **
'**********************************************************************

'
' Change the 3 "AD" bits to reflect the I2C address of the device
' (corresponding to A0,A1 and A2)..
'
Dim Mcp23016_adress_w As Byte
Mcp23016_adress_w = &H40 'Write Adress: 0 1 0 0 A2 A1 A0 0

Dim Mcp23016_adress_r As Byte
Mcp23016_adress_r = &H41 'Read Adress: 0 1 0 0 A2 A1 A0 1

Dim Counter_1 As Byte
Dim Lsb As Byte
Dim Msb As Byte


'This is for the Microchip MCP23016 initialization, some examples below

'Call I2c_mcp23016_write(&H04 , &Hff , &Hff) 'Invert All Input Polarities
'Call I2c_mcp23016_write(&H0a , &H01 , &H01) 'Initialize Iares , For Fast Input Scan Mode

'Call I2c_mcp23016_write(&H06 , &H00 , &HFF) 'Initiallize It So The Lsbs Outputs Are & Msbs Are Inputs
'Call I2c_mcp23016_write(&H06 , &Hff , &Hff) 'Initiallize It So That Both Lsbs & Msbs Are Inputs

'Call I2c_mcp23016_write(&H02 , &HFF , &HFF) 'Initiallize The Ouput Latch
'Call I2c_mcp23016_write(&H06 , &H00 , &H00) 'Initiallize It So That Both Lsbs & Msbs Are Outputs



'**********************************************************************
'** Actual work starts here.  **
'**********************************************************************


Main:

Waitms 250 ' wait 250 ms for the MCP23016 powerup timer

Call I2c_mcp23016_write(&H02 , &HFF , &HFF) 'Initiallize The Ouput Latch
Call I2c_mcp23016_write(&H06 , &H00 , &H00) 'Initiallize It So That Both Lsbs & Msbs Are Outputs

Lsb = &HFE '0 => Led is "on" FE => 11111110
Msb = &HFE '0 => Led is "on" FE => 11111110

Counter_1 = 0

Do 'Chaser effect

Call I2c_mcp23016_write(&H02 , Lsb , Msb) 'Write Lsb & Msb to MCP23016

Rotate Lsb , Left , 1 'Rotate the bits
Rotate Msb , Left , 1
Waitms 100 'Wait 100ms
Counter_1 = Counter_1 + 1 ' Increase the counter

Loop Until Counter_1 = 255 ' As long as the counter is not 255 keep writing & rotating

Lsb = &HFF '0 => Led is "on" FF => 11111111
Msb = &HFF

Call I2c_mcp23016_write(&H02 , Lsb , Msb) 'All leds off

Call I2c_mcp23016_write(&H06 , &H00 , &HFF) 'Initiallize It So The Lsbs Outputs Are & Msbs Are Inputs

Do 'Read Msb and display on Lsb

Call I2c_mcp23016_read ' Read Msb
Print "Msb: " ; Msb ' Send value of Msb to serial port
Lsb = Msb ' Copy Msb to Lsb
Call I2c_mcp23016_write(&H02 , Lsb , Msb) ' Write Lsb to MCP23016
Wait 1

Loop

End 'end program


'**********************************************************************
'** Define Subroutines **
'**********************************************************************
Sub I2c_mcp23016_write(byval Cmd As Byte , Byval Lsb As Byte , Byval Data2 As Byte)
' Writes data to the I2C MCP23016.

 I2cstart 'Generate A Start Condition
 I2cwbyte Mcp23016_adress_w 'Transmit The "ADDRESS and WRITE" Byte
 I2cwbyte Cmd 'Transmit The Command Byte
 I2cwbyte Lsb 'Transmit First Data Byte
 I2cwbyte Msb 'Transmit Second Data Byte
 I2cstop 'Generate a STOP condition
 Waitus 50 'Some delay may be necessary for back to back transmitions

End Sub

Sub I2c_mcp23016_read
' Read data from the I2C MCP23016

 I2cstart 'Generate START condition
 I2cwbyte Mcp23016_adress_w 'Transmit The "ADDRESS and WRITE" Byte
 I2cwbyte &H00 'Transmit The Command Byte
 I2cstop 'Generate a STOP condition
 I2cstart 'Generate a START condition
 I2cwbyte Mcp23016_adress_r  'Transmit ADDRESS with READ command
 I2crbyte Lsb , Ack 'Receive first DATA byte (LSB) and acknowledge
 I2crbyte Msb , Nack 'Receive second DATA byte (MSB) and don't acknowledge
 I2cstop 'Generate a STOP condition

End Sub