The I2C Slave add on can turn some chips into a I2C slave device. You can start your own chip plant this way.

 

Most new AVR chips have a so called TWI interface. As a customer of the I2C slave lib, you can get both libs.

The TWI slave lib works in interrupt mode and is the best way as it adds less overhead and also less system resources.

 

In the following example the code for older compilers

 

Example

'-----------------------------------------------------------------------------------------

'name                     : twi-slave.bas

'copyright                : (c) 1995-2005, MCS Electronics

'purpose                  : shows an example of the TWI in SLAVE mode

'micro                    : Mega128

'suited for demo          : yes

'commercial addon needed  : yes

'-----------------------------------------------------------------------------------------

 

$regfile = "m128def.dat"                                   ' specify the used micro

$crystal = 8000000                                         ' used crystal frequency

$baud = 19200                                               ' use baud rate

$hwstack = 32                                               ' default use 32 for the hardware stack

$swstack = 10                                               ' default use 10 for the SW stack

$framesize = 40                                             ' default use 40 for the frame space

 

 

' Not all AVR chips have TWI (hardware I2C)

' IMPORTANT : this example ONLY works when you have the TWI slave library

' which is a commercial add on library, not part of BASCOM

 

Print "MCS Electronics TWI-slave demo"

 

Config Twislave = &H70 , Btr = 1 , Bitrate = 100000

 

 

'as you might need other interrupts as well, you need to enable them manual

 

Enable Interrupts

 

'this is just an empty loop but you could perform other tasks there

Do

nop

Loop

End

 

'A master can send or receive bytes.

'A master protocol can also send some bytes, then receive some bytes

'The master and slave must match.

 

'the following labels are called from the library

Twi_stop_rstart_received:

Print "Master sent stop or repeated start"

Return

 

 

Twi_addressed_goread:

Print "We were addressed and master will send data"

Return

 

 

Twi_addressed_gowrite:

Print "We were addressed and master will read data"

Return

 

 

'this label is called when the master sends data and the slave has received the byte

'the variable TWI holds the received value

Twi_gotdata:

Print "received : " ; Twi

Return

 

'this label is called when the master receives data and needs a byte

'the variable twi_btr is a byte variable that holds the index of the needed byte

'so when sending multiple bytes from an array, twi_btr can be used for the index

Twi_master_needs_byte:

Print "Master needs byte : " ; Twi_btr

Twi = 65                                                 ' twi must be filled with a value

Return

 

 

'when the mast has all bytes received this label will be called

Twi_master_need_nomore_byte:

Print "Master does not need anymore bytes"

Return