I'm working with a MBa6ULX board which have an TQMA6ULx. The board has an 8bit I/O port i2c with three buttons. I'm trying to get the status of these buttons by console. The I2c device has 0x21 address.
If I execute the command i2cdetect -y 3 I get the next info:
If I try to read the registers of the 0x21 device:
Why I get the UU in the address of my I2C devices?
I have found the following interpretation of the "UU" output on a Linux man page:
"UU". Probing was skipped, because this address is currently in use by a driver. This strongly suggests that there is a chip at this address.
I am not able to reproduce the issue of the i2c detect command, since we do only support our Linux BSP and boards. I would suggest you to get in contact with TQ so they help you more properly to address the solution to your problem using their board:
You can also try to debug the I2C bus using a logic analyzer to determinate whether the device does respond with an acknowledge or find out if a wiring problem exists.