From: Fred P. <fp...@cs...> - 2006-02-20 21:39:53
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So, I'm having trouble getting the gumstix to talk to my digital compass, and I'm wondering if it's due to the pull up resistors I am using. The compass is 5v, so should I pull up to 3.3v for the gumstix, or 5v for my compass? Or, does it even matter? Thanks, Fred |
From: Dave H. <dhy...@gm...> - 2006-02-20 21:56:22
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On 2/20/06, Fred Potter <fp...@cs...> wrote: > So, I'm having trouble getting the gumstix to talk to my digital > compass, and I'm wondering if it's due to the pull up resistors I am > using. > > The compass is 5v, so should I pull up to 3.3v for the gumstix, or 5v > for my compass? Or, does it even matter? If you're connecting directly to the gumstix, then it shouldn't be pulled up above 3.3v. If you're using the robostix, then it has on-board 5v pullups. 5v devices should still see the 3.3v as a logic high. What value resistors are you using? -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Fred P. <fp...@cs...> - 2006-02-20 22:13:43
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I'm using 4.7k resistors. I'll go ahead and try pulling up to 3.3v first. Thanks to both of you for responding. Fred On 2/20/06, Dave Hylands <dhy...@gm...> wrote: > On 2/20/06, Fred Potter <fp...@cs...> wrote: > > So, I'm having trouble getting the gumstix to talk to my digital > > compass, and I'm wondering if it's due to the pull up resistors I am > > using. > > > > The compass is 5v, so should I pull up to 3.3v for the gumstix, or 5v > > for my compass? Or, does it even matter? > > If you're connecting directly to the gumstix, then it shouldn't be > pulled up above 3.3v. > > If you're using the robostix, then it has on-board 5v pullups. > > 5v devices should still see the 3.3v as a logic high. > > What value resistors are you using? > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > > ------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. Do you grep through log fi= les > for problems? Stop! Download the new AJAX search engine that makes > searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! > http://sel.as-us.falkag.net/sel?cmdlnk&kid=103432&bid#0486&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Achim W. <awa...@gm...> - 2006-02-20 22:01:07
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Fred, IMO the gumstix does not tolerate 5V levels on the I2C ports. You have to pull up to 3.3V. I'm using a bidirectional level shifter like the MAX3373. A cheaper solution can be found here: http://cs.gmu.edu/~eclab/projects/robots/flockbots/pmwiki.php?n=Main.Gumstixmods I wonder if this works well... Achim. Fred Potter wrote: > So, I'm having trouble getting the gumstix to talk to my digital > compass, and I'm wondering if it's due to the pull up resistors I am > using. > > The compass is 5v, so should I pull up to 3.3v for the gumstix, or 5v > for my compass? Or, does it even matter? > > Thanks, > > Fred > > > ------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. Do you grep through log files > for problems? Stop! Download the new AJAX search engine that makes > searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! > http://sel.as-us.falkag.net/sel?cmd=k&kid3432&bid#0486&dat1642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > > |