From: Rob B. <ro...@gm...> - 2007-02-01 19:05:21
|
I am planning to connect a sensor, that outputs at 5V, to the Rx of a UART on the GPSstix. I know the GPSstix runs at 3.3V, so would it be better (with respect to power, performance, and noise) to step this voltage down closer to 3.3V before connecting it to the GPSstix? Thanks. -RobB |
From: Dave H. <dhy...@gm...> - 2007-02-01 19:13:53
|
Hi Rob, On 2/1/07, Rob Barnes <ro...@gm...> wrote: > I am planning to connect a sensor, that outputs at 5V, to the Rx of a UART > on the GPSstix. I know the GPSstix runs at 3.3V, so would it be better (with > respect to power, performance, and noise) to step this voltage down closer > to 3.3V before connecting it to the GPSstix? Not only would it be better, but it's REQUIRED. Connecting 5v up to anything on the gpsstix could damage things. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Rob B. <ro...@gm...> - 2007-02-01 19:17:26
|
Do you have any advise on the best way to do this. Voltage divider, diodes, voltage regulator... Thanks. On 2/1/07, Dave Hylands <dhy...@gm...> wrote: > > Hi Rob, > > On 2/1/07, Rob Barnes <ro...@gm...> wrote: > > I am planning to connect a sensor, that outputs at 5V, to the Rx of a > UART > > on the GPSstix. I know the GPSstix runs at 3.3V, so would it be better > (with > > respect to power, performance, and noise) to step this voltage down > closer > > to 3.3V before connecting it to the GPSstix? > > Not only would it be better, but it's REQUIRED. Connecting 5v up to > anything on the gpsstix could damage things. > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job > easier. > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Dave H. <dhy...@gm...> - 2007-02-01 19:20:42
|
On 2/1/07, Rob Barnes <ro...@gm...> wrote: > Do you have any advise on the best way to do this. Voltage divider, diodes, > voltage regulator... It depends on the signal, and how frequently it changes, whether its an input or an output, etc. For simple inputs which don't change rapidly, a resistor divider will often work fine. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Rob B. <ro...@gm...> - 2007-02-02 00:14:17
|
I should have been more verbose in my first post. It's an IR receiver module that will be outputting a 0.2-4.5V digital square wave. This will be connected to a UART port and read as a serial input. It will be receiving at about 1.2Kbits/s. Thanks for the help. -RobB On 2/1/07, Dave Hylands <dhy...@gm... > wrote: > > On 2/1/07, Rob Barnes < ro...@gm...> wrote: > > Do you have any advise on the best way to do this. Voltage divider, > diodes, > > voltage regulator... > > It depends on the signal, and how frequently it changes, whether its > an input or an output, etc. > > For simple inputs which don't change rapidly, a resistor divider will > often work fine. > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ <http://www.davehylands.com/> > > ------------------------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job > easier. > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Nate L. <sol...@gm...> - 2007-02-01 19:33:19
|
On 2/1/07, Dave Hylands <dhy...@gm...> wrote: > On 2/1/07, Rob Barnes <ro...@gm...> wrote: > > Do you have any advise on the best way to do this. Voltage divider, diodes, > > voltage regulator... > > It depends on the signal, and how frequently it changes, whether its > an input or an output, etc. > > For simple inputs which don't change rapidly, a resistor divider will > often work fine. This is assuming that it is a digital input. If it is an analog input from say a strain gauge, I think that you will be better off swapping out the instrumentation amplifier on the sensor for one that outputs at 3.3V. With an analog sensor you basically need to transform the 0-5V range into a 0-3.3V range. If you just step it down to 3.3V you readings will be all screwed up..... > > -- > Dave Hylands > Vancouver, BC, Canada > http://www.DaveHylands.com/ > > ------------------------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job easier. > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users > |
From: Dave H. <dhy...@gm...> - 2007-02-01 22:20:36
|
Hi Nate, > This is assuming that it is a digital input. If it is an analog input > from say a strain gauge, I think that you will be better off swapping > out the instrumentation amplifier on the sensor for one that outputs > at 3.3V. With an analog sensor you basically need to transform the > 0-5V range into a 0-3.3V range. If you just step it down to 3.3V you > readings will be all screwed up..... Yep - absolutely correct on the analog portion. An op-amp would should do the trick for that. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |