## Re: [Gumstix-users] I2C question

 Re: [Gumstix-users] I2C question From: Brian Davidson - 2005-07-28 20:14:40 ```Check out =20 http://cs.gmu.edu/~eclab/projects/robots/pmwiki/pmwiki.php?=20 n=3DMain.Gumstixmods The I2C bus requires pullup resistors, so you can control the voltage =20= level of the bus. Just set it to 3.3 volts, and it will work. 3.3 =20 volts is "high" in TTL logic, so the 5 volt parts will still work. The resistor pack we came up with is a voltage divider, plus 2 pullup =20= resistors. Brian Davidson George Mason University On Jul 28, 2005, at 3:59 PM, Terry Frederick wrote: > I'm attempting to connect a 5 V part to the gumstix using I2C.=A0 =20 > It=A0looks to me that the PXA255 is not 5 V tolerant on it's I/O.=A0 = The =20 > 5V part can handle 3.3 Volt I/O.=A0 Do I need an interface to connect =20= > these two chips?= ```

 [Gumstix-users] I2C question From: Terry Frederick - 2005-07-28 20:00:24 Attachments: Message as HTML ```I'm attempting to connect a 5 V part to the gumstix using I2C. It looks = to me that the PXA255 is not 5 V tolerant on it's I/O. The 5V part can = handle 3.3 Volt I/O. Do I need an interface to connect these two chips?```
 Re: [Gumstix-users] I2C question From: Brian Davidson - 2005-07-28 20:14:40 ```Check out =20 http://cs.gmu.edu/~eclab/projects/robots/pmwiki/pmwiki.php?=20 n=3DMain.Gumstixmods The I2C bus requires pullup resistors, so you can control the voltage =20= level of the bus. Just set it to 3.3 volts, and it will work. 3.3 =20 volts is "high" in TTL logic, so the 5 volt parts will still work. The resistor pack we came up with is a voltage divider, plus 2 pullup =20= resistors. Brian Davidson George Mason University On Jul 28, 2005, at 3:59 PM, Terry Frederick wrote: > I'm attempting to connect a 5 V part to the gumstix using I2C.=A0 =20 > It=A0looks to me that the PXA255 is not 5 V tolerant on it's I/O.=A0 = The =20 > 5V part can handle 3.3 Volt I/O.=A0 Do I need an interface to connect =20= > these two chips?= ```