I have few of i2c devices that was successfully tested working with RPi Zero W (Tiny RTC, BME280), but no one is visible to NanoPi Neo Air board with Armbian. I can't get it to work on latest few versions of Armbian. 

 

As soon as I add i2c0 to overlays there appears two of i2c devices (both silent):

$ ls -la /dev/i2c*
crw-rw---- 1 root i2c 89, 0 Jan 28 14:58 /dev/i2c-0
crw-rw---- 1 root i2c 89, 1 Jan 28 14:58 /dev/i2c-1

 

I need to admit that scan itself took quite significant amount of time.

$ sudo time i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
0.00user 0.04system 3:59.62elapsed 0%CPU (0avgtext+0avgdata 1036maxresident)k
0inputs+0outputs (0major+64minor)pagefaults 0swaps

 

Since it could be a problem with pull-up resistors, I've tried to add 4K7 resistors to SDA and to SCL lines, but situation remains the same.

 

What am I doing wrong? What step is missed? Will appreciate any help. Thank you.

51 minutes ago, Nazar Gerasymchuk said:

could be a problem with pull-up resistors

Yes, since there are no ones onboard ...

52 minutes ago, Nazar Gerasymchuk said:

What am I doing wrong?

Don't know ... Could be that you mistakenly crossed SDA and SCL ?

Thank you for quick response, @martinayotte

 

> Could be that you mistakenly crossed SDA and SCL ?

 

Checked and re-checked for a lots of times, tried different jumpers and different breadboards.

 

Unfortunately I have no oscilloscope to check if i2c bus is working, but are there any ways to test the bus? E.g.: what does it means if i2cdetect scan takes so much time? Could it signalize something? 

8 minutes ago, Nazar Gerasymchuk said:

what does it means if i2cdetect scan takes so much time?

"i2cdetect -y 0" should be almost instantenous, left than half second for the whole 127 addresses !

If it takes about 1 seconds per address, this means you pullups are defective, or they are placed on the wrong pins.