Hello,
When I asked, I dream of using soft I2C, I don't know if it is possible, however next answer by Fadil Berisha give a soluce OUT OF Uext connector. It is sufficient for me now. Thanks. I have OlinuxIno-Maxi, rev B
as mentioned in manual jumpers are set to soft:

ware i2c .
I plan to use i2c for two low traffic peripherals:
- Dallas DS1307 clock (3 $ on ebay: http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=200763022338&ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
- Microchip mac-address eprom ( http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2542¶m=en538878&redirects=mac )
Question: is it mandatory to modify the two jumpers (I don't have miniature solder iron) ?
Is it a way to use i2c with unmodified board?
Regards
PO.
Post Scruiptum: At this time, I have connected Ds1307 (Vcc to +3.3, Grnd, Scl, Sda) to Uext, and i2cdetect give nothing.
May be I do another error.