On 2013-04-11 14:24, Julian Brooks wrote:

Hey Martin / list,

Finally got all the stuff and ...

It’s not working!

We spent the day soldering cables and connecting stuff up as per the
Omron ‘App Note 01’ spec sheet.

Started off super-conservative using the  I2C level converter (case 3
page 4) http://www.adafruit.com/products/757#Blog/Flickr

We tried resistors on both sides (being super paranoid!) and then we
took  the low (Pi) side ones off.

We then moved on to case 2 page 3 of this same document…

At each stage we checked with “I2Cdetect –Y 1” and nothing was visible.

The grid shows no attached devices every time we run it.

We re-booted at every stage following the various online
tutorials/methods of setting up I2C GPIO on the Pi (checked & double
checked).


As you can see we’re using a pi protoplate:

https://www.adafruit.com/products/801

In the photo I’ve attached the cables are coded as follows:

Orange           GND

Yellow            5v

Blue                SCL

Green             SDA

The white is also 5v for the pull up resistors.

The resistor values are 4.7k btw.

We have tested the cable that terminates at the sensor and all that is OK.

I put a multimeter on the GND and SDA solder points on the sensor itself
and got 3.7v…

I put a multimeter on the GND and SCL solder points on the sensor itself
and got 0.0v…

If you have pullup resistors you should get the same 3.7V on SCL (with it switched on and not running any code), so probably your pin isn't connected somewhere.

Martin