gians
Posts: 8
Joined: Tue Sep 18, 2012 2:25 pm

device not found

Fri Sep 21, 2012 9:24 am

hello,
I'm doing the first experiments with I2C
typing $ sudo i2cdetect -y 0
read:

Code: Select all

 0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
does not seem to be anything connected :oops:

I accidentally wrote $ sudo i2cdetect -y 1
With this result: :o

Code: Select all

 0  1  2 3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- 77
It seems give signs of life :)
I'm testing the BMP085 by AdaFruit
but what does it mean i2cdetect -y 1 works !
in place of i2cdetect -y 0 ?? :?
In this case how to read the address?

thank you very much
Giuseppe

ailwyn
Posts: 29
Joined: Sun Jan 08, 2012 9:52 pm

Re: device not found

Sat Sep 22, 2012 7:11 am

Can you describe or post a picture of where you've connected the i2c clock and data lines?

I thought that the second i2c channel was not on the main header (but am currently away from my Pi so can't check)

A.

gians
Posts: 8
Joined: Tue Sep 18, 2012 2:25 pm

Re: device not foundsecond channel i2c

Sat Sep 22, 2012 1:16 pm

thanks for your answer
I'm somewhat surprised because afaik I did not know a second channel i2c who were on GPIO :o
On the same line of power supply 3.3v
and just immediately next to supply is connect the data
and soon after there is clock.
:?: But how can I change the address for my device?

best regards

Giuseppe

Blars
Posts: 88
Joined: Sun Aug 28, 2011 3:22 am
Contact: Website

Re: device not foundsecond channel i2c

Sat Sep 22, 2012 3:32 pm

gians wrote: :?: But how can I change the address for my device?
Depends on the device, read the data sheet. Most I2C chips have one or two address pins, that you tie high or low to change the address. Sometimes there are ways to get more addresses, by leaving open, tieing to one of the i2c lines, etc.

gians
Posts: 8
Joined: Tue Sep 18, 2012 2:25 pm

Re: device not found

Sat Sep 22, 2012 4:44 pm

:oops: sorry I expressed myself badly :oops:
I mean how to communicate to the address 0x77
on the second i2c channel by Raspberry :arrow:
because my Raspberry it seems to set up in this way.

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