Hi everone ,

I am looking for a way to use two I2C sensors with the same I2C address of the same I2C port.

Regards,

 

Hi everone ,

I am looking for a way to use two I2C sensors with the same I2C address of the same I2C port.

Regards,

It doesn't work that way. You have three choices:
1. You find a way to change one of the addresses
2. You get a new sensor with a different address.
3. You use a different interface.
Regards,
Keith

 

If the two lines SCL and SDA are all you have then you'll be looking for a long time to make this happen. Where do you guys come up with stuff like this?
Incroyable!

 

Some sensors allow their address to be changed. Look into it. Otherwise use a jumper.

 

Some sensors allow their address to be changed. Look into it. Otherwise use a jumper.

That is not an option. He wants two devices with the same address to play nice on the bus with each other. Ain't gonna happen.

 

He may not be aware that one of his devices may have a changeable address.

 

You can produce a second I2C port by driving the SCL and SDA lines to each sensor via an analog mux and select the sensor that way. Or bit bang another I2C port. Or a second Arduino.
But as mentioned above, the sensors need to have different addresses, or I2C ports.

 

You can produce a second I2C port by driving the SCL and SDA lines to each sensor via an analog mux and select the sensor that way. Or bit bang another I2C port. Or a second Arduino.
But as mentioned above, the sensors need to have different addresses, or I2C ports.

Can you provide me with more details about the mux solution ?

 

Have a look at something like a CD4052 dual analog multiplexer.

Connect X and Y to SDA and SCL on the Arduino.
X1 and Y1 to sensor 1 SDA and SCL.
X2 and Y2 to sensor 2 SDA and SCL.
A to a port pin used to select the sensor, and B to 0V for just 2 sensors, or another port pin for 4 sensors.
INH to 0V
VEE and VSS to 0V
VDD to 5V

make sure both sensors have pullup resistors.

https://www.ti.com/lit/ds/symlink/cd4051b.pdf

 

Hi everone ,

I am looking for a way to use two I2C sensors with the same I2C address of the same I2C port.

Regards,

An I2C multiplexer would get you that functionality if you're not able to change the addresses of either of the devices. TCA9548A is one such device. You can find board for a few dollars on eBay.

Adafruit have a nice write-up on using one. https://learn.adafruit.com/adafruit-tca9548a-1-to-8-i2c-multiplexer-breakout/overview

 

Have a look at something like a CD4052 dual analog multiplexer.

Connect X and Y to SDA and SCL on the Arduino.
X1 and Y1 to sensor 1 SDA and SCL.
X2 and Y2 to sensor 2 SDA and SCL.
A to a port pin used to select the sensor, and B to 0V for just 2 sensors, or another port pin for 4 sensors.
INH to 0V
VEE and VSS to 0V
VDD to 5V

make sure both sensors have pullup resistors.

https://www.ti.com/lit/ds/symlink/cd4051b.pdf

What is the connection of the pullup resistors ?

 

For one sensor keep the SDA and SCL the way you have it... for the other sensor swap the SDA and SCL. in software talking between the two just reassign the SDA or SCL depending on which sensor you want to talk to.

Note: This will only work if you have two sensors with the same address on the I2C buss. We did this all the time over the years when I was an employee at Parallax Inc. ... i.e. a p;opular I2C memory expansion card utilized this method

 

For one sensor keep the SDA and SCL the way you have it... for the other sensor swap the SDA and SCL. in software talking between the two just reassign the SDA or SCL depending on which sensor you want to talk to.

Note: This will only work if you have two sensors with the same address on the I2C buss. We did this all the time over the years when I was an employee at Parallax Inc. ... i.e. a p;opular I2C memory expansion card utilized this method

Can you clarify more ?

 

For one sensor keep the SDA and SCL the way you have it... for the other sensor swap the SDA and SCL. in software talking between the two just reassign the SDA or SCL depending on which sensor you want to talk to.

That is very clever!
I'm not sure how hard it is to do with the Arduino. Probably have to bit bang it, not use the inbuilt I2C.
Maybe someone else can clarify.

 

What are the sensors you are using?
Why can’t you use individual sensor addresses? I’ve never seen this scenario. Sensor addresses are always customizable that I have seen.