0

Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Mon Jul 12, 2021 10:08 pm

Hello Adafruit,

I am working on a project that I am to use the Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout https://www.adafruit.com/product/2717 to connect the d6t1a02 temperature sensors https://www.arrow.com/en/products/d6t1a02/omron to. I am using a jetson nano and I would like to know if you have any python sample code for using the Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout with board's I2C connection?

Thank you in advance.

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by dastels on Mon Jul 12, 2021 10:25 pm

You can look at the support in the CircuitPython bundle. It's at least a good place to start. https://github.com/adafruit/Adafruit_CircuitPython_TCA9548A

Dave

dastels
 
Posts: 7226
Joined: Tue Oct 20, 2015 3:22 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Tue Aug 03, 2021 1:22 am

Hello everyone,

I was able to get the sensor running.

Now I have switched boards and I have another question if you can help I appreciate it I am running the tca program to find the ports but this is what I get:

"TCAScanner ready!
TCA Port #0
Found I2C 0x60
Found I2C 0x6A
TCA Port #1
Found I2C 0x60
Found I2C 0x6A
TCA Port #2
Found I2C 0x60
Found I2C 0x6A
TCA Port #3
Found I2C 0x60
Found I2C 0x6A
TCA Port #4
Found I2C 0x60
Found I2C 0x6A
TCA Port #5
Found I2C 0x60
Found I2C 0x6A
TCA Port #6
Found I2C 0x60
Found I2C 0x6A
TCA Port #7
Found I2C 0x60
Found I2C 0x6A

done"

It is all connected
what does this means?

Thank you

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by dastels on Tue Aug 03, 2021 10:01 am

What hardware do you have connected and how?

Dave

dastels
 
Posts: 7226
Joined: Tue Oct 20, 2015 3:22 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Tue Aug 03, 2021 12:32 pm

Hello Dave,

I have the d6t1a02 temperature sensors https://www.arrow.com/en/products/d6t1a02/omron connected to the Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout https://www.adafruit.com/product/2717 on SDA1 and SCL1 that is connected to the I2C on the Arduino RP2040(pins A4 -SDA and pin A5-SCL) and I am using a circuit in between those to reduce the voltage in half for the Arduino pin, and the Arduino is connected to a jetson nano. I can get the sensor to work alone but when I add it to the I2C chip it does not work.

Thanks

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by dastels on Tue Aug 03, 2021 12:43 pm

What exactly do you mean by
I am using a circuit in between those to reduce the voltage in half for the Arduino pin


Dave

dastels
 
Posts: 7226
Joined: Tue Oct 20, 2015 3:22 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Tue Aug 03, 2021 1:06 pm

The Arduino pin input is 3.3v and the output of the i2c expander is 5v. So I am stepping down the voltage to the Arduino.

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by dastels on Tue Aug 03, 2021 2:12 pm

Are you using an I2C level shifter?

Dave

dastels
 
Posts: 7226
Joined: Tue Oct 20, 2015 3:22 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Tue Aug 03, 2021 5:08 pm

No I am not.

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by dastels on Tue Aug 03, 2021 5:34 pm

Then how are you "stepping down the voltage"?

You should use https://www.adafruit.com/product/757.

Dave

dastels
 
Posts: 7226
Joined: Tue Oct 20, 2015 3:22 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Wed Aug 04, 2021 12:16 am

I did it before with in-series resistors. I don’t know why it does not work with the Arduino Nano RP2040 Connect.

I have a few questions. Is the BSS138 plug and play? I mean does it need any code?

From what I see you plug in the ‘grounds’ and also High voltage and get Low voltage with jumper wires from the other end? Is it that simple?

Thank you again

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by dastels on Wed Aug 04, 2021 9:06 am

You have to be careful with I2C (and SPI) as whatever you use has to be fast enough not to smooth the edges of the signal.

The BSS138 is a single MOSFET based circuit. No code, it's just discrete electronics. You have a 3.3v device on one side and a 5v device on the other (as a common example). 3.3v connects to LV, 5v connects to HV, gnd connects to the ground on each side (but are all common as expected) 3.3v signal connect to A1-A4, corresponding 5v signals connect to B1-B4. E.g. SDA from the on the 3.3v side connects to A1 and SDA from the 5v side connects to B1, and so on.

Jumper wires? Be careful, any connections to the board should be soldered.

Dave

dastels
 
Posts: 7226
Joined: Tue Oct 20, 2015 3:22 pm

Re: Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout

by Laron on Thu Aug 05, 2021 9:17 pm

Here is a picture of my set up. The board does not seem to recognize anything.
The board at top is an Arduino nano RP2040 Connect , then down one is the level shifter abs at bottom is the I2C expander.

When running the I2C expander only I get the same output:
"TCAScanner ready!
TCA Port #0
Found I2C 0x60
Found I2C 0x6A
TCA Port #1
Found I2C 0x60
Found I2C 0x6A
TCA Port #2
Found I2C 0x60
Found I2C 0x6A
TCA Port #3
Found I2C 0x60
Found I2C 0x6A
TCA Port #4
Found I2C 0x60
Found I2C 0x6A
TCA Port #5
Found I2C 0x60
Found I2C 0x6A
TCA Port #6
Found I2C 0x60
Found I2C 0x6A
TCA Port #7
Found I2C 0x60
Found I2C 0x6A

done"

Connecting one single sensor to the I2C on the board works fine.

Thanks
Attachments
041BD810-3D18-43D4-BF68-419D4BF0AF12.jpeg
041BD810-3D18-43D4-BF68-419D4BF0AF12.jpeg (451.24 KiB) Viewed 44 times

Laron
 
Posts: 9
Joined: Mon Jul 12, 2021 10:03 pm

Please be positive and constructive with your questions and comments.