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THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL

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THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226196

By SDW –  Wed May 26, 2021 8:36 amCurrently I’m working on a project where I want to use multiple scales in a fridge. When something will be taking out of the fridge the scale detects the different weight and send an event to my server. I’m really a noob to I2C and at this moment I can’t figure out why it’s not working…

I’m using a Raspberry Pi 4 Modal B with a pHat attached to the GPIO pins. From there I use a Qwiic cable to connect the bus to a PCA9615. Then I use a 2m S/FTP cable to connect the other PCA9615. Then the signal goes to a TCA9548A to use the bus with 8 different channels. I need the 8 channels because the I2C address of the NAU7802 is 0x2A and is hardware defined. A multiplexer/Mux is required to communicate to multiple NAU7802 sensors on a single bus.

Now the problem that I’m facing is that everything is working correctly when I don’t use the I2C Bus Extender. I see all of my channels and I can change the channel to retrieve the weight of the multiple scales. But when I connect the I2C Bus Extender there is only 1 channel working and the other channels are not available. Is there any solution how to fix this problem?

Products that I use:

  • SparkFun Qwiic pHAT v2.0 for Raspberry Pi
  • SparkFun QwiicBus – EndPoint
  • SparkFun Qwiic Mux Breakout – 8 Channel (TCA9548A)
  • SparkFun Qwiic Scale – NAU7802

Schematic
Image

The red lines are indicating that the connection is not working. I only see 1 NAU7802 when I use the i2cdetect command. Now when I disconnect the red lines but connect the green line, everything is working correctly. But that’s unfortunately not what I want to achieve.

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226199

By TS-Chris –  Wed May 26, 2021 9:36 amThe only thing I can think of that would be causing issues is that you might not be able to push enough current down the CAT5 cable for all the devices on the remote end to work properly.

You might try opening JP1 on the differential board on the remote end and then connecting a 3.3 volt power supply between VDDB and GND and see if that clears things up.SparkFun Electronics, Inc.
6333 Dry Creek Parkway
Niwot, CO 80503

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226208

By SDW –  Wed May 26, 2021 12:18 pmThank you for your reply.

If I use my multimeter I see that GND and VCC1 is giving back 3.29 / 3.30 volts. So maybe it has enough voltage?
You’re suggesting that I should cut the 0-1 jumper. But where can I find the VDDB on my v11 Bus Extender? I can only see the VCC1 / GND and VCC2 / GND2 connectors.

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226211

By TS-Chris –  Wed May 26, 2021 12:43 pmWhat products are you using? Your photo shows two of BOB-14589 but you seem to be describing COM-16988.SparkFun Electronics, Inc.
6333 Dry Creek Parkway
Niwot, CO 80503

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226213

By SDW –  Wed May 26, 2021 12:50 pmSorry for the confusion. I’m using the most recent one: https://www.sparkfun.com/products/16988

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226224

By TS-Chris –  Wed May 26, 2021 2:32 pmOK, it looks like the newer board is laid out a bit differently. I haven’t tested this, but from what I gather, you need to cut the 0-1 jumper on the board connected to your Pi, and on the remote end, connect 3.3 volts to 3V3 and GND. That provides power to the remote devices without anything going back down the cable.

I’m hoping this does the trick for you!SparkFun Electronics, Inc.
6333 Dry Creek Parkway
Niwot, CO 80503

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226240

By SDW –  Thu May 27, 2021 5:42 amUnfortunately with the external 3.3v it’s still not working correctly. I’ve cut the 0-1 jumper on the PCA9615 that is connected to the Raspberry Pi. The S/FTP cable is connected to the other PCA9615 and there the power indicator is still off. So that is a good thing, because the 0-1 cut is working.

Then I connect 3.3v to the PCA9615 and I see that the power indicator is on. After that I do a test to see if I can see all NAU7802 boards that are connected to the TCA9548A. None of them are showing when I do the i2cdetect command:
CODE: SELECT ALL

pi@raspberrypi:~ $ i2cdetect -l
i2c-15	i2c       	i2c-1-mux (chan_id 4)           	I2C adapter
i2c-13	i2c       	i2c-1-mux (chan_id 2)           	I2C adapter
i2c-1	i2c       	bcm2835 (i2c@7e804000)          	I2C adapter
i2c-11	i2c       	i2c-1-mux (chan_id 0)           	I2C adapter
i2c-18	i2c       	i2c-1-mux (chan_id 7)           	I2C adapter
i2c-16	i2c       	i2c-1-mux (chan_id 5)           	I2C adapter
i2c-14	i2c       	i2c-1-mux (chan_id 3)           	I2C adapter
i2c-12	i2c       	i2c-1-mux (chan_id 1)           	I2C adapter
i2c-17	i2c       	i2c-1-mux (chan_id 6)           	I2C adapter
pi@raspberrypi:~ $ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 11
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 12
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 13
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 14
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 15
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 16
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 17
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --                         
pi@raspberrypi:~ $ i2cdetect -y 18
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- -- -- -- -- -- --       

And when I don’t use both PCA9615 boards I can see 1 NAU7802 connected, but that’s not what I want to achieve.

My setup:
Image

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RE: THE DIFFERENTIAL I2C BUS EXTENDER IS ONLY WORKING FOR 1 CHANNEL#226241

By SDW –  Thu May 27, 2021 5:59 amI’ve tried to connect a I2C device with a different address. Now I see the LCD screen connected. I’m really confused, now it looks like a problem with the NAU7802?
CODE: SELECT ALL

pi@raspberrypi:~ $ i2cdetect -y 11
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: UU -- 72 -- -- -- -- --   

Setup:
Image Reply

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