Jetson TX2 communication with PCA9685 using i2c


I am currently trying to make Jetson TX2 (with orbitty carrier board) communicate with a PCA9685 manufactured by Adafruit.

The issue is that the orbitty carrier board has only one pair of i2c pin(i.e., one pair of SDA and CLK), but I am using two i2c devices including one PCA9786(for several pwm control signals) and one HTADCI2C chip(for analog sensor reading).

I connected both devices(PCA9685 and HTADCI2C) to one pair of SDA and CLK as shown in the attached picture.

Then, I checked addresses of each device using “sudo i2cdetect -y -r 0” command, but only HTADCI2C shows correct address (which is 0x28 at bus 0). That is, it supposed to show 0x70 at either bus 0 or bus 1 for PCA9685, but I only can see,

0x71 at bus 0,
0x72 at bus 0,
0x50 at bus 7.

Also, when I checked above three addresses using “sudo i2cdump 0 0x71”, it doesn’t seem to show correct values as shown in the attached pictures.

Are there anyone who had this kind of issue?

Website for PCA9685:
Website for HTADCI2C:

What’s the i2cdetect result if disconnect PCA9685?
Looks like the PCA9685 slave address can configure you may need to confirm the configure.

Dear Mr. ShaneCCC,

Thank you very much for the quick response.
When I detached a PCA9685, the i2cdetect does not show

0x71 at bus 0,
0x72 at bus 0,

as shown in the attached pictures.