Second "silent" master on I2C bus

Hi,

I hope this isn’t a redundant question, but I have searched on google and got flooded with semi related topics that didn’t address my question.

I have a setup with an Arduino Mini integrated into a PCB. The Mini receives sensor data through Bluetooth (on the serial port) and controls two DACs through I2C. I would like to change my setup and use a Yun to receive the data through WiFi, but use that same circuit to control the DACs - then I wouldn’t have to change anything in my setup besides adding the new board. The idea is to connect the Yun’s I2C pins to the Arduino’s pins to control my DACs.

The code on my Arduino Mini looks somewhat like this:

#include <Wire.h>   
#include <Adafruit_MCP4725.h>

Adafruit_MCP4725 dac1;
Adafruit_MCP4725 dac2;

void setup() {
dac1.begin(0x60);
dac2.begin(0x61);
Serial.begin(115200);
}

void loop() {
while(Serial.available()){
dac1.setVoltage(SensorValue1, false);
dac2.setVoltage(SensorValue2, false);
}
}

If I change my setup, there will be no more data coming through the serial bus, so the Mini will not send any requests to the DACs. I am just not sure, how it will react, if at all, if some other master (the Yun) starts using the bus.

Thanks in advance.
Nik

The code on my Arduino Mini looks somewhat like this

We can talk when you are able to say "looks exactly like this".

If I change my setup, there will be no more data coming through the serial bus, so the Mini will not send any requests to the DACs. I am just not sure, how it will react, if at all, if some other master (the Yun) starts using the bus.

It won't send requests but activates the hardware. The Wire library activates the internal pull-up resistors.

If you connect the Yun, load a sketch on your Mini that does exactly nothing. Then you should be fine with the described setup.

Thank you, this clarifies a lot