TCA9543A: How can scan i2c device connected to TCA9543A ?

Jaecheon Yoo

Part Number: TCA9543A

Tool/software:

Hi, experts

Address 0x70 for this TCA9543APWR product is being scanned by the host.

Currently we've connected i2c devices (MAX96714GTJ/VY+T) to TCA9543APWR via CAM1_I2C and CAM0_I2C net, but it doesn't seem to be scanned.

When I o-scope i2c from host (SOC_I2C2) before passing TCA9543A, good signaling of i2c detected
but when I o-scope i2c after the MUX (CAM0/CAM1_I2C) there were no signal detected.

If the device has a lower level i2c devices connected to CAM1_I2C or CAM0_I2C, is it correct that the devices is scanned without any special settings on the host?

If there is something to set to scan devices please let me know.

10 months ago

+1 Clemens Ladisch 10 months ago

Guru 301610 points

Scanning is done with normal I²C accesses. So devices on a channel are scanned only if that channel is enabled.

The host must configure the switch correctly before scanning each channel.

0 Jaecheon Yoo 10 months ago in reply to Clemens Ladisch

Intellectual 916 points

This was guidance for configuring each channel to enable i2c in the data sheet.
I could scan slave devices by this cmd. Thanks.

Setting bus to 3
=> i2c probe
Valid chip addresses: 70
=> i2c mw 0x70 0x1 0x2
=> i2c probe
Valid chip addresses: 2A 40 50 6D 70

+1 Clemens Ladisch 10 months ago in reply to Jaecheon Yoo

Guru 301610 points

Jaecheon Yoo said:
i2c mw 0x70 0x1 0x2

Please note that the TCA9543A has only a single control register and no register address, so only a single byte should be written. In this case, only the last byte written (0x2) has an effect; the previous byte (0x1) is ignored.

0 Jaecheon Yoo 10 months ago in reply to Clemens Ladisch

Intellectual 916 points

so then what is the full cmd for this case?

when I perform like this , there is no value for the device so error occurs

=> i2c mw 0x70 0x2

i2c mw chip address[.0, .1, .2] value [count] - write to I2C device (fill)

0 Jaecheon Yoo 10 months ago in reply to Clemens Ladisch

Intellectual 916 points

and one more thing.

what does that mean chip address[.0, .1, .2] at description ? should we type 0 1 or 2 after chip address?

+1 Clemens Ladisch 10 months ago in reply to Jaecheon Yoo

Guru 301610 points

As far as I can see, uboot requires the suffix to be the address length. The TCA9543A does not have a register address, so you have to use zero:

i2c mw 0x70 0.0 0x2

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TCA9543A: How can scan i2c device connected to TCA9543A ?