Undocumented I2C device at 0x6A on the Notecarrier-X

Hardware
1

Title: Undocumented I2C device at 0x6A on Notecarrier-X v1.3 (with NOTE-MBGLW)

Body:

Hi, while I was bringing up a NOTE-MBGLW on a Notecarrier-X v1.3, an I2C scan of the host bus found a device at 0x6A next to the Notecard at 0x17. It only answers when the Notecard and its Notecarrier-X are on the bus. The Notecarrier-X datasheet and the Notecard I2C documentation don’t mention it.

Setup:

Notecard NOTE-MBGLW, firmware notecard-11.4.1.17828 (board 5.13)
Notecarrier-X v1.3, connected over Qwiic to an ESP32-S3 host
Bus: 100 kHz. The only other device is a BME280 at 0x76.
Scan result: 0x17, 0x6A, 0x76. Without the Notecard and carrier: 0x76 only.
Questions:

What is the part at 0x6A? Is it on the Notecarrier-X (for example the LiPo charger) or on the Notecard itself?
Is its address fixed, and is a host allowed to talk to it, or should it be left alone?
Could it be added to the Notecarrier-X datasheet (and the Notecard I2C notes), so people can plan around it when they pick other I2C parts? 0x6A is also a common address for IMUs and chargers (for example LSM6DS3 and BQ2589x), so an undocumented clash is easy to run into.
Thanks!

2

Hey @Joseph_G_Solch,

Welcome to the Blues community, and thanks for reaching out with this.

The device at 0x6A is a LiPo charger on the Notecarrier X (a TI BQ25628E). The charger shares the Notecard’s I2C bus, and its address is fixed in the chip, so unfortunately it can’t be changed.

I’m going to get this added to the datasheets today. If you have any other questions let me know.

Thanks,

TJ VanToll