Issues with i2c bus using MultiCam Adapter v2.1

Hello, I am trying to incorporate the multicam adapter into a project I am working on where I have a number of other devices on the i2c bus. I have been running into issues with the adapter where once I write it’s mux via i2c it causes reads from other sensors to fail randomly. While investigating this, i found that the adapter has 3 i2c addresses, 0x70, 0x64, and 0x40. I suspect that this is the culprit for the issues I am seeing.

I have tried reconnecting it without any other i2c devices, and am still seeing the same 3 addresses in use. Any insights into this would be greatly appreciated.


The 0x70 is the address of the onboard i2c switching chip. The 0x64 is the address of the onboard encryption chip. What’s strange is the 0x40 address. Please attach me your hardware connection and I will help you check it in detail.

Okay, that address belongs to a sensor I hadn’t realized was on the bus, that is not the issue unfortunately.

The issue I am seeing is that once I write to the MultiCam Adapter through SMBus, i2cset, or pigpio, it causes “Errno 121 remote i/o error” when reading from other devices on the bus. I am reading from 3 other sensors and they all read with no errors for hours, but once I start trying to capture images and enabling the adapter i immediately start to see intermittent 121 errors on all 3 sensors. This isn’t caused by the adapter being connected as the other sensor work fine with it connected, but once it’s written to it causes this problem.

As far as I know, this issue usually indicates the device with the specified address can’t be found, but I don’t see how this adapter could be causing this issue. Do you have any insights as to why this is occurring?



Oh. Maybe I know the issue. When you run the camera, the camera will occupy the i2c0 , when you connect our multi adapter board, our board will connect the i2c1 to i2c0. So when the GPU adjust the camera’s exposure time and awb. both i2c0 and i2c1 will be influenced. So other slave devices will be influenced.