12

I was trying to turn on I2C following this tutorial http://www.raspberrypi-spy.co.uk/2014/11/enabling-the-i2c-interface-on-the-raspberry-pi/

But I have problem which I cannot solve. The command i2cdetect -y 1 returns

     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10: 10 11 12 13 14 15 16 17 18 19 1a UU 1c 1d 1e 1f
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
50: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: 70 71 72 73 74 75 76 77

I don't know why it shows all addresses and how can I fix this. I didn't connect anything to my Raspberry Pi. I've just put SD card and installed default OS using NOOBS. But when problem appeared I connected my RTC DS1307 but it didn't affect on i2cdetect output.

  • Pin 3 was the answer for me. I had an LED on pin 3 and when I moved it, the interface cleared up. – SaintMulligan Oct 27 '17 at 10:27
15

Generally this happens because something is pulling SDA (pin 3) low.

The i2cdetect program checks for the existence of a device by sending its address then letting SDA float high. If the device exists it should pull SDA low to signal its presence.

Check your wiring to make sure SDA hasn't been inadvertently connected to ground.

  • I've used multimeter putting first test lead on SDA and second test lead on GND. I've found there is connection between them. Is it wrong? – wja Jun 20 '15 at 22:08
  • Check the voltage between pin 3 and pin 6 (ground). It should read 3V3. If it does not there is seomthing wrong. Do you have anything connected to the expansion header like a ribbon cable? – joan Jun 20 '15 at 22:15
  • It's 0.06V between pin 3 and 6. I have nothing connected to my device. – wja Jun 20 '15 at 22:19
  • I'd examine the PCB tracks to see if there is a solder bridge. Do you have a gpio library installed? Pin 3 would read low if it was actively being driven low, but by default it should be floating high. – joan Jun 20 '15 at 22:31
  • PCB looks fine. I have fresh Raspbian with updates. I thought gpio library is required only if I want to write code in Python. Should I install python-rpi.gpio? Or maybe there is other gpio library? – wja Jun 20 '15 at 22:37
1

Fixed my PI zero... Near SDA (pin 3) and the SD card slot there are two resistors, touched the connections with a soldering iron and it works now.

0

In my case it was because broken i2c device was connected (I accidentally reverse connected it to voltage/ground before)

Try using another i2c device

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.