how to use i2c-8 on Xavier's Expansion Header?

hello:
I need communicate to the slave device through Xavier’s i2c-8(pin3 and pin5) on the Expansion Header, but i can’t detect the slave device using “i2cdetect -y -r 8”; the jetpack version is L4T-4.1.1, what should i do next?

I don’t know if this helps. I’m using i2c as part of the SMBus protocol. Here is some Python code that I can use to read one of the parameters for my battery. I believe that I had to install i2c-tools first but that may have been just to run i2cdetect. If you can’t see your device, then I’d look at those pins using an oscilloscope to see if you are even getting a signal on the I2C line.

from smbus import SMBus

def getBatteryMode(whichBus = 8):
b = SMBus(whichBus)
try:
return b.read_word_data(11,0x03)
except:
print “There was an exception when trying to read the battery mode”
return -1

Thanks for your reply!!
my problem is solved, it turns out that my slave device’s circuit is not right;
i can detect the slave device using i2cdetect command now.