borzeckid
Posts: 2
Joined: Sat Mar 07, 2015 5:13 pm

i2c shows nothing on my rpi b2 (solved)

Sat Mar 07, 2015 6:52 pm

Hello,

This is my first post, so I don't want to get on anyones wrong side by posting some trivial problem.. But unfortunately it's not something fresh either. I've bought rpi 2 b last week and have been trying some of my older gear from arduino. Lately however, I've been struggling with setting up my LCD (standard hd44780) which is connected through i2c backpack with pcf8574 expander.

I'm pretty sure, I've dig through every topic about this issue on this board and none of mentioned solutions worked for me. Few details:
* my device tree is properly populated: dtparam=i2c_arm=on as well as few others are present in /boot/config.txt
* latest version of firmware installed and all packages upgraded
* uname -a gives: Linux raspberrypi 3.18.8-v7+ #765 SMP PREEMPT Thu Mar 5 15:47:06 GMT 2015 armv7l GNU/Linux
* lsmod | grep i2c:
i2c_dev 6027 2
i2c_bcm2708 4990 0
* even though device is crossed: sudo i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
* I've checked (thanks to this post http://www.raspberrypi.org/forums/viewt ... 14#p590656) if it's due to problem with input voltage level. I've connected i2c Vcc to different power supply and tried various levels with no results.

Hope that someone could give me some more ideas, it's almost a week since I've started testing this LCD.

borzeckid
Posts: 2
Joined: Sat Mar 07, 2015 5:13 pm

Re: i2c shows nothing on my rpi b2

Sun Mar 08, 2015 8:34 pm

Just a quick update, I've just checked on arduino and turns out it doesn't work either. Probably something wrong with my i2c backpack :lol:

User avatar
Richard-TX
Posts: 1549
Joined: Tue May 28, 2013 3:24 pm
Location: North Texas

Re: i2c shows nothing on my rpi b2 (solved)

Mon Mar 09, 2015 4:11 am

When using raspi-config, there is a set procedure to enable the I2C bus.

The steps are.

1 - enable device tree
2 - enable i2c.

If you previously disabled device tree, the you have to re-enable i2c after re-enabling the device tree.
Richard
Doing Unix since 1985.
The 9-25-2013 image of Wheezy can be found at:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2013-09-27/2013-09-25-wheezy-raspbian.zip

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