Scenario 1
When powering this shield from Arduino 5V and GND, everything works fine. The cardinfo example sketch under SD works flawlessly.
Scenario 2
When using external 5V 700mA power supply, I connect +ve terminal to Vcc and -ve terminal to GND of the shield. This shield refuses to work. I get initialization failure message in serial console when using the same cardinfo example sketch. All other connections i.e. CS, SCK, MISO, and MOSI are the same as in scenario 1.
Scenario 3
I suspected some issue with power supply, hence I replaced it with USB power supply 5V 1A. The +ve (RED) of USB was connected to Vcc and -ve (Black) was connected to GND. Results are same as scenario 2.
I suspect power supply issue as the shield is working perfectly when drawing power from Arduino. I googled a lot and could not find any answer to above problem. Hence I would appreciate if someone can throw some light on getting SDCard shield working with external/USB power supply.
Thanks for the reply. My background is not electronics, hence my question may seem stupid. My 5V power supply has 2 outputs i.e. one is +ve and other -ve. How do I get ground out of these two connections?
Did some googling and attached diagram is what I understood. Can you verify if this is the correct way of connecting modules to Arduino? If yes, can multiple modules be connected in the same way?
Power supply used is USB 5V.
thanks for the reply. My original connections were the same as described by you. But I could not get SDCard to work. SDCard works only when power and GND are supplied from Arduino. I think my power supply may not be providing exact 5V. Will get a multimeter tomorrow and check voltages.
I did check the voltage in power supply. It was 5.11V. My earlier diagram was wrong. Correct diagrams attached to this post. When power is supplied from Arduino, SDCard works and when supplied from external power, SDCard does not work. I have run out of ideas, any suggestions will be helpful.
