i2c Mux Board Bad?

riffelrw
Junior Member

Posts: 65

i2c Mux Board Bad? Sept 7, 2021 18:25:40 GMT -8

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Post by riffelrw on Sept 7, 2021 18:25:40 GMT -8

Have an i2c mux board that I'm trying to integrate into an arduino / adafruit feather. Have hooked it up and the mux board powers up, an i2c scan finds it at address 0x73 and the blue LED is on next to the PC connector. However connecting up a grove device on any of the channels is not seen, while it is found if I connect directly to the arduino so I know it's good.

Here is the output from the SD test program, when it scans the bus it finds phantom devices on all channels, and the LED's for each channel will not activate:

I'm guessing I fried the board somewhere along the way, I had it for some time in my shop, it worked awhile ago. Just looking for any fast ideas before i move on and just buy another.

thanks

SDL Global Moderator Posts: 5,650 Raspberry Pi: Yes Other Device: PC, arduino, beagleBone	i2c Mux Board Bad? Sept 10, 2021 9:50:25 GMT -8 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by SDL on Sept 10, 2021 9:50:25 GMT -8 Sounds fried to me. Odd output thought! It looks like all the channels are connected together. Any chance of a static zap along the way? that will kill devices like this. BP

riffelrw
Junior Member

Posts: 65

i2c Mux Board Bad? Sept 10, 2021 17:58:13 GMT -8

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Post by riffelrw on Sept 10, 2021 17:58:13 GMT -8

I actually figured it out - I misunderstood the function of the scan routine and the chip itself. The duplicate entriess were because there were other i2c devices on the input to the board, so when the device scanned it kept seeing these along with the mux at 0x73. I also didn't get the fact you could write a 0x00 to the control register to disconnect all the fanouts so I can see what is on each bus by comparison to the devices when all busses are isolate (I have an application with dynamic i2c placements so I dont know where each item will be - plug and play kind of thing).

I also figured out with nothing connected to J8 none of the LED's turn on however connecting VCC on the PC side to J8 enabled each Bus LED to light. Is this normal, that you have to supply J8 to enable the LED's?

SDL Global Moderator Posts: 5,650 Raspberry Pi: Yes Other Device: PC, arduino, beagleBone	i2c Mux Board Bad? Sept 13, 2021 14:55:03 GMT -8 Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by SDL on Sept 13, 2021 14:55:03 GMT -8 Yes, that is normal. Take a look at the specification to see what J8 is used for. BP

Post by riffelrw on Sept 7, 2021 18:25:40 GMT -8

Post by SDL on Sept 10, 2021 9:50:25 GMT -8

Post by riffelrw on Sept 10, 2021 17:58:13 GMT -8

Post by SDL on Sept 13, 2021 14:55:03 GMT -8

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