Using usitwislave on ATmega328 (arduino uno)

[maali-mnasri]

Hi,
I wonder if this library "usitwislave" can be used on ATmega328p (arduino uno) or at least is there a chance to make it run on ATmega if I adapt the registers to my device ?

[eriksl]

I wonder if this library "usitwislave" can be used on ATmega328p
(arduino uno) or at least is there a chance to make it run on ATmega if
I adapt the registers to my device ?

You don't need this library on an ATmega328p, this microcontroller has a
"complete" hardware supported twi/i2c, it's no "USI" implementation. You
can find USI mainly on "ATtiny" devices.

[maali-mnasri]

For a special case I need to use a software I2C (slave) library and not the I2C hardware module of the ATmega. USI is not implemented on ATmega328p but isn't it similar to USART ? Don't you think it (usiTwiSlave) may function on ATmega if I change the register names to the USART registers? Thank you.

[eriksl]

On 24-04-14 00:27, ilaam wrote:

For a special case I need to use an I2C slave software library and not
the I2C hardware module of the ATmega. USI is not implemented on
ATmega328p but isn't it similar to USART ? Don't you think it may
function on ATmega if I change the register names to the USART
registers? Thank you.

I see your point but the library is really tailored for USI, including
timings. I guess you'll have to search e.g. for i2c using bitbanging
(which I am sure do exist). I know the USART on the ATmega328p can be
used as secondary SPI device, but that's really something different.
It's a nice challenge ;-)

I guess you need the TWI pins for something else ;-)

[maali-mnasri]

Yes exactly TWI pins are already used.
Thank you for your reply 👍 Now that you told me it's challenging to try to adapt usiTwiSlave to USART, I'll try again to find some bitbanging i2c lib because I already searched and all I could find were i2c master libraries not slave ones .