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Thread: 2 different I2C addresses with PIC
face BY : Keith H email (remove spam text)

Tero Leppanen wrote:
> Has anyone tried to receive I2C data with two different I2C
> addresses ?
> Actually, I meant receiving (or sending) data with one slave mode
> PIC, which have two different I2C addresses.... Both addresses should
> be available all the time.

This could be a useful way of replacing multiple I2C devices with one,
but you can't do this with a PIC. It only has one slave address
register, and you can't make it ignore any bits.
The I2C spec says all devices should respond to a broadcast
address (zero) but I dont know any device that does.
However if you do need a broadcast address (e.g. for emergency
failsafe or reset messages) then zero would be the one to use.

You could have external jumpers read to set the address.

It's completely possible to have I2C messages which say
"your I2C slave address is now..." or
"your I2C slave address should be your default"
which is a "jumperless" equivalent.
This technique is used in access.bus (I2C based)and
SDS DeviceNet (CANbus based) devices.
Amusing cosmology quotations:

<361350BF.2047@arcam.co.uk> 7bit

See also: www.piclist.com/techref/i2cs.htm?key=i2c
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