TMP102 over i2c not detected

[Joey19990]

Hi, this is my first time posting. I've really been having trouble getting any readings from the TMP102 on my Model B Raspberry Pi. Specifically I have this version of the TMP102:
https://www.sparkfun.com/products/11931

I've followed the instructions for detecting the sensor from this website (which seems to be the same as the other instructions).
http://donalmorrissey.blogspot.co.uk/20 ... orial.html

When I do i2cdetect -y 0 the Pi does not detect the TMP102 (even if I do -y 1). I'm still pretty new to the Raspberry Pi as well as the interface, so perhaps this is just a noob problem, but hopefully I can learn from you all. Thanks in advance!

-Joey

[joan]

Could you describe the connections you have made between the sensor and the Pi? A photo of your set-up may also be useful.

[Joey19990]

From the TMP102 to the Pi I have
Vcc plugged into 3v3 power (top left pin)
Gnd plugged into ground (third pin from the top on the right)
SDA plugged into GPIO 0 (SDA) (Second pin from the top on the left)
SCL plugged into GPIO 1 (SCL) (thrid pin from the top on the left)
ALT plugged into ground
ADD0 not plugged in

[joan]

The spec says you need a pull up resistor on ALT (alert). So ALT should probably be connected to a gpio with its internal pull-up enabled or to 3.3V through a circa 5K resistor. For testing you could leave it disconnected.

The ADD0 pin should be connected to ground or 3.3V to fix the address. I'd connect it to ground.

[Joey19990]

So I connected the ADD0 pin on the TMP102 to ground on the Pi, and still I'm not detecting the TMP102 at all. Thanks for the reply btw.

[Joey19990]

Hi, I'm still having trouble getting any readings from the TMP102, I have connected it as suggested earlier, but still nothing.

[hampi]

Works for me. I was playing with that board yesterday evening and wrote a small C daemon 'tmp102d' to log the temperatures to /var/log/tmp102d.log.

Edit: On the Sparkfun web page there is a new version of that board. It seems that you can set the chip address with a solder link on the board and external connection on ADD0 is not necessary any more. The board has three pull up resistors and one filtering capacitor for the power.

[Joey19990]

Just wanted to let you all know that I finally got it to work. It was the combination of having add0 to ground, and alt to 3.3v via 5k resistor. Without the resistor it just wouldn't work for me. Weird, but it works. Thanks everyone for your help!