Linking Arduinos

Hi, I have seen that it is possible to link 2 Arduino boards together and the information says that more can be added. On the schematic it links ground->ground, 4->4 and 5->5 in serial, how can I link Arduino boards 3, 4 etc. is it the same pins? I suspect on the master that I would need to somehow expand the connection ability of the ground, & pins 4 & 5? Is there a simple connector I could use? It would in the end need to be user friendly as each board would act as a plugin.

Appreciate the steer.

Kind regards, jB 8)

I suspect they mean A4 and A5 which are the I2C SCL and SDA lines. Each Arduino slave is given an I2C address (Wire.begin(address)) so they can all use the same pair of wires.


Thanks for the reply. Sorry to be so pedantic, does this mean

That Slave 1 A4 goes to Master A4 Slave 1 A5 goes to Master A5 Slave 1 Gr goes to Master Ground That Slave 2 A4 goes to Master A4 Slave 2 A5 goes to Master A5 Slave 2 Gr goes to Master Ground That Slave 3 A4 goes to Master A4 Slave 3 A5 goes to Master A5 Slave 3 Gr goes to Master Ground etc...


jB 8)

I think I would go Master A4 to Slave1A4 to Slave2A4 to ... SlaveXA4 to a 4.7K pullup to +5V. Master A5 to Slave1A5 to Slave2A5 to ... SlaveXA5 to a 4.7K pullup to +5V. Connect all Gnd's similarly.

Thank you.

So to be exact it would be a daisy chain rather than a star style connection? The connection of a 4.7K pullup to +5V, I have to admit consfuses me at this stage to what does that connect or is that like a terminal end as in the old style BNC networks.

I am only just starting out and have both electronics and arduino books on the go at the same time, so will eventually learn (I hope), but at this stage I get a tad confused when the unexpected slaps me round the back of the neck.

Patience appreciated.

Kind reagrds,

jB 8)

Yes, daisy chain. I2C bus needs a pullup termination resistor, the parts apparently can pull signals low, but not drive high, hence the pullup.

Thank you very much to everyone for their support. I feel much more confident now... (Probably just slammed myself now (grin)).

Kind regards,

jB 8)