external 5V connection usage and the SEL jumper on a sensor shield

On my v5.0 sensor shield, there is a terminal strip for external 5V power. I am reluctant to just connect 5V to it, as I am wondering how it works without conflicting with the power already being supplied from the Arduino board. There is a small jumper next to the terminal strip, labelled SEL. Is that used to isolate the power somehow? (also a schematic would help me figure it out if one exists anywhere)

A clue as to what shield you are talking about (as in a link) would be good.

PaulS: A clue as to what shield you are talking about (as in a link) would be good.

OK, sorry, I thought the designs were sort of standardised and that the version 5.0 would be sufficient description. This one: http://www.amazon.com/SainSmart-Sensor-Digital-Arduino-Duemilanove/dp/B0076FWAAK or http://www.emartee.com/product/42015/ or http://www.arduinosale.com/arduino-sensor-shield-v5-0-sensor-expansion-board-electronic-building-blocks-of-robot-parts.html

Is that used to isolate the power somehow? (also a schematic would help me figure it out if one exists anywhere)

Could very well be. The best path to take is to use a digital multimeter in resistance or 'continuity' mode and measure between the all the Vcc pins on the male pins and either the shield 5V pin or the external 5vdc screw terminal, to see how the voltage source works with the jumper clip in one position or the other and with no jumper at all. The voltage source should come from either the 5V shield pin or the external 5 volt screw terminal source. That should give you a clear picture of how it works and if it works for what you want to do.

Lefty

retrolefty:

Is that used to isolate the power somehow? (also a schematic would help me figure it out if one exists anywhere)

Could very well be. The best path to take is to use a digital multimeter in resistance or 'continuity' mode and measure between the all the Vcc pins on the male pins and either the shield 5V pin or the external 5vdc screw terminal, to see how the voltage source works with the jumper clip in one position or the other and with no jumper at all. The voltage source should come from either the 5V shield pin or the external 5 volt screw terminal source. That should give you a clear picture of how it works and if it works for what you want to do.

Lefty

Good idea, just try it with a multimeter - should have thought of that.

I read somewhere, earlier today, that some shields use it to change the power source for the digital interfaces, but not the analog inputs. Probably because it's assumed the digital devices will be the ones needing more power (for relays etc). I am betting I will find this one is similar.

digimate:

retrolefty:

Is that used to isolate the power somehow? (also a schematic would help me figure it out if one exists anywhere)

Could very well be. The best path to take is to use a digital multimeter in resistance or 'continuity' mode and measure between the all the Vcc pins on the male pins and either the shield 5V pin or the external 5vdc screw terminal, to see how the voltage source works with the jumper clip in one position or the other and with no jumper at all. The voltage source should come from either the 5V shield pin or the external 5 volt screw terminal source. That should give you a clear picture of how it works and if it works for what you want to do.

Lefty

Good idea, just try it with a multimeter - should have thought of that.

I read somewhere, earlier today, that some shields use it to change the power source for the digital interfaces, but not the analog inputs. Probably because it's assumed the digital devices will be the ones needing more power (for relays etc). I am betting I will find this one is similar.

Be sure you pass on the results of your testing. I own a V4 of the sensor shield board and find it very useful for quick proto/testing of circuit ideas. But the V4 offers no 5volt external voltage source. I might have to lool into upgrading as using external +5vdc power can be very useful at times, especially when working with servos.

EDIT:

I see that can be quite inexpensive: http://www.ebay.com/itm/1-X-Sensor-Shield-V5-V5-0-For-Arduino-APC220-Bluetooth-Analog-Module-Servo-Motor-/140797596106?pt=LH_DefaultDomain_0&hash=item20c830d1ca

Looking at the bottom trace layout, it looks to me that the jumper clip is put in place when you want the normal arduino 5V pin to power the digital male 'servo pins' power, and if you want to use an external +5vdc you just remove the jumper clip and wire up an external voltage to the screw terminals. It would appear to me all the other 5vdc male or female pins are not selectable and only get power from the shield 5V pin ( but I'm not sure about the LCD connector positions, best to measure). That is a workable solution for getting external power for R/C hobby servos with a minimum of wiring hassle. Lefty

Took out the old multimeter, and tested things. Removing the SEL jumper, removes internal power from the 14 digital GVS connections, but leaves power on the 6 analog inputs, as well as the serial and LCD connectors. Didn’t have the pinout handy for the specialty connectors for APC220 module, Bluetooth, SD card, and URF - but I expect they’ll retain internal power too.

digimate: Took out the old multimeter, and tested things. Removing the SEL jumper, removes internal power from the 14 digital GVS connections, but leaves power on the 6 analog inputs, as well as the serial and LCD connectors. Didn't have the pinout handy for the specialty connectors for APC220 module, Bluetooth, SD card, and URF - but I expect they'll retain internal power too.

Good. Some of the vendors provide better pinout information on the various connectors, such as the end of this listing: http://www.ebay.com/itm/New-Sensor-Shield-V5-Expansion-digital-analog-module-for-Arduino-328-UNO-/221131907418?pt=LH_DefaultDomain_0&hash=item337c7d215a

Lefty

Excellent info, just what I was looking for. I found that the Uno board can not supply sufficient current for a MG996, and so an additional current supply is required.

I'm glad that I noticed the SEL jumper, else I may have ended up with a fried Uno.