Twiggy Sticks
Posts: 7
Joined: Thu Oct 04, 2012 11:29 am

Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Oct 04, 2012 11:50 am

Hi there,
I have attached the BMP085 to the Raspberry Pi as directed by Adafruit: http://learn.adafruit.com/using-the-bmp ... spberry-pi

However when I run $ sudo i2cdetect -y 0, no device is detected.
I have uploaded images of the way I have attached the BMP085, as well as the Raspberry Pi's output.

Thanks.
Attachments
Pi Output.jpg
Pi Output.jpg (58.87 KiB) Viewed 5289 times
BMP085 Attachment 2.jpg
BMP085 Attachment 2.jpg (62.41 KiB) Viewed 5289 times
BMP085 Attachment 1.jpg
BMP085 Attachment 1.jpg (60 KiB) Viewed 5289 times

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joan
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Oct 04, 2012 1:04 pm

The photos are not quite clear enough. On attachment 1 you appear to be connecting xclr.

I'd try

pin 1(3V3) to 3V0.
pin 3 to SDA.
pin 5 to SCL.
pin 6 to GND.

Twiggy Sticks
Posts: 7
Joined: Thu Oct 04, 2012 11:29 am

Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Oct 04, 2012 1:10 pm

Yes that is how I have set it up. Sorry about the images they are very low res.

Serac
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Oct 04, 2012 3:31 pm

Did you load the i2c_bcm2708 kernel module along with the usual i2c core drivers ?

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joan
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Oct 04, 2012 3:37 pm

Serac wrote:Did you load the i2c_bcm2708 kernel module along with the usual i2c core drivers ?
Is manually modprobing i2c_bcm2708 a recent requirement? I haven't used i2c for several days on the Pi and tried using it today. Thought it must be broken when I didn't get the expected devices.

Frank B
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Oct 04, 2012 4:11 pm

I2C Installation for Raspberry Pi – Step by Step Guide:

http://www.skpang.co.uk/blog/archives/575

Twiggy Sticks
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Fri Oct 05, 2012 12:34 am

I have installed i2c using that guide, however the Adafruit tutorial didn't say anything about modprobing?? What is this?

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joan
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Fri Oct 05, 2012 8:00 am

To load a module and its dependencies you can use the command modprobe.

Try

sudo modprobe i2c_bcm2708

The raspbian variants of Debian have that module blacklisted in /etc/modprobe.d but it is needed for a working i2c system.

Mind you in your case I wouldn't have though i2cdetect would have worked if you don't have i2c_bcm2708 loaded.

Twiggy Sticks
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Joined: Thu Oct 04, 2012 11:29 am

Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Fri Oct 05, 2012 8:35 am

I have loaded that module as well as i2c-dev however the BMP085 is still not getting detected.

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joan
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Fri Oct 05, 2012 10:09 am

If you have another i2c sensor try using that instead.

If you have another i2c enabled micro (e.g. Arduino) try using that instead.

You may have a damaged unit or a damaged Pi.

CONNECT AT YOUR OWN RISK. I would try connecting pin 2(5V) to VIN rather than pin 1(3V) to 3V0. However posters suggest that a 5V I2C interface will damage the Pi itself via (presumably) SDA/SCL.

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PeterO
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Fri Oct 05, 2012 12:37 pm

joan wrote: CONNECT AT YOUR OWN RISK. I would try connecting pin 2(5V) to VIN rather than pin 1(3V) to 3V0. However posters suggest that a 5V I2C interface will damage the Pi itself via (presumably) SDA/SCL.
It would only be a problem if the external i2c device has bus pull ups fitted that are connected to 5V. There is no need for external devices to have pull ups fitted as the PI has them fitted, and they are connected to 3V3 not 5V.

Since the external devices only pull i2c lines down to 0V a 5V powered device won't put 5V onto the GPIO pins.

PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
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hamzehk1990
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Wed Jun 05, 2013 3:51 pm

Hi,

I am a Pi noob 8-) and I have the same problem that you are talking about here.
Did you solve it? and if you did can you tell me how ?

Thanks

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liudr
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Wed Jun 05, 2013 6:21 pm

From the picture the OP was connecting the I2C sensor by jabbing the jumper pins into the board's holes. That's a very poor way to make connections. You should solder on some female header on the sensor and then connect to it with jumper wires.
Arduino data loggers, user interface, printed circuit board designer since 2009, RPI 3B 2B 2B Zero Jessie, assembly/C/C++/java/python programmer since the 80's

hamzehk1990
Posts: 3
Joined: Wed Jun 05, 2013 3:48 pm

Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Jun 06, 2013 10:10 am

Hi and thanks for the fast reply :)
I changed the connections to the raspberry pi , but still no result.
Its very disappointing, because there aren't a lot of forums talking about this problem.

I am using a BMP085 pressure sensor connected to the
3.3v (pin 1 ) for VCC
GND to GND
SDA (pin 3 / GPIO0) to SDA on sensor
SCL (pin4 / GPIO1) to SCL on sensor

The i2cdetect does not show any connection!!!
Please help

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liudr
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Jun 06, 2013 5:48 pm

Did you read my reply? Your connections to the sensors need to be soldered. You can NOT just stab the holes with jumper wire leads. Is that so hard to understand?
Arduino data loggers, user interface, printed circuit board designer since 2009, RPI 3B 2B 2B Zero Jessie, assembly/C/C++/java/python programmer since the 80's

gsh
Raspberry Pi Engineer & Forum Moderator
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Jun 06, 2013 6:35 pm

Are you sure you're using the same revision of the RPi that the adafruit info used? Don't forget that the I2C changed from rev1 to rev2.... (the pins are in the same place but connected to different pins on 2835)

Gordon
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Raspberry Pi - Director of Software Engineering

didolgi
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Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Fri Jun 07, 2013 9:35 pm

There are very simple directions at adafruit to enable i2c at
http://learn.adafruit.com/adafruits-ras ... guring-i2c

If you haven't followed those steps yet you don't have i2c up and running. As was said by an earlier poster - you must solder either wire or a header to the BMP085 - the holes will NOT conduct current if you just put a piece of wire in them.

hamzehk1990
Posts: 3
Joined: Wed Jun 05, 2013 3:48 pm

Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Tue Jun 11, 2013 1:08 pm

I checked the version of my Pi ...
it is a model B , 256 MB ram
so the pins are rev.2 (The connection pins I belief are correct )

As for the BMP085 I originally soldered wires onto it, and checked that there is a connection to the chip.
I followed the adafruit i2c instructions to the letter , twice now. and tried the same thing on a different raspberry pi (same specs).

I guess that there might be a fault with the sensor :?

TechColab
Posts: 27
Joined: Tue Mar 06, 2012 10:27 am

Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Thu Jun 20, 2013 12:22 pm

I have one of these on each I2C bus & they both work fine. Double check that you've done ALL of the bits in Adafruit's documentation, following all the tangent links for sub-steps. Roughly this should include:
Good soldering, no solder blobs or dry joints.
Use the correct GPIO pins for your RPi.
Update your Raspian "sudo apt-get update && sudo apt-get -y upgrade"
Remove the modules from the black list /etc/modprobe.d/raspi-blacklist.conf
Add the modules to the auto-load list /etc/modules
Install the various i2c tools & Adafruits software (apt & git)
Set the pi users's permissions "sudo adduser pi i2c"
Reboot
Check if you can see it "sudo i2cdetect -y 0 ; sudo i2cdetect -y 1"
If you still don't see a 77 in there, then you've either received a faulty one, or possibly damaged it.

If you know someone else nearby with a RPi & a ready-made i2c device that plugs directly into the GPIO header, then you could try swapping things about to prove it one way or the other.

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