Dear Sir, I am new to Pololu and Arduino too and seek to ask for help in this forum- I have just purchased the Dual Motor driver shield VNH5019 and stacked it over the Arduino. The Shield and the UNO work fine and the motors coasts in both the direction with a fine pwm speed control as per the sketch. My question is- With the Shield connected to 24VDC power (VIN & GND) and the JUMPER ON (page 10 of cat), Can I connect my laptop’s USB to the Arduino UNO USB port to do the online programming?
24V is well beyond the recommended 12V maximum for powering the Arduino UNO and is right at the upper limit of the shield. You should probably use a lower-voltage power supply, especially if you want to use it to power both the shield and the Arduino. As for having the power connected through the shield while programming, (assuming it is an appropriate voltage) that is the same as powering the Arduino through its DC power jack while USB is connected. Arduino intends for this to work, but we generally do not recommend doing so for the reasons mentioned in this forum thread.
Dear Sir, Thanks for your guidance and safety recommendation regarding the USB and power connection for the Arduino UNO R3 and the Pololu VNH5019. In fact it was my blunder, for not referring the page 8 of the catalogue.
Method 1 – If using 24VDC Supply or Power above 12VDC
Jumper OFF , Plug USB to program Arduino or Power Jack on Arduino IN. (Page 8)
Method 2 – If using 7 to 12 VDC Supply
Jumper ON, Plug USB to program Arduino, Power Jack on Arduino OUT. (Page 10)
Please correct me on the above if my reading of VNH5019 cat and writing over here makes sense.
Your understanding seems correct.