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Topic: Custom Arduino board resets on inserting SD card (Read 1 time) previous topic - next topic


I'm working on the second version of a Digital Color Communication badge. It has a microSD slot for loading of images.

The MicroSD slot has a card detect line, which is super useful in theory. In practice, it causes some issues.

The DigiBadge starts up just fine if there's a card in the slot, or if there's not a card in the slot. It runs just like it's supposed to if the card is removed while running.

If a card is inserted, the whole thing resets.

I thought putting a resistor in-line would fix the problem. I was wrong.

The MicroSD slot is a push/push model that brings the Card Detect pin to ground when the card is inserted. In the current design, the pin is connected to Digital 7 on an ATMega328-AU (Physical pin 11). I've confirmed no shorts in the soldering.

Full schematics and the program I'm running can be found here.

Any insight into this would be greatly appreciated.


Jun 07, 2016, 01:54 am Last Edit: Jun 07, 2016, 06:07 am by AndonRT
I just had a thought: Perhaps the SD card being inserted is causing a small, temporary short from supply voltage to the ground (Thus resetting the whole thing). If this is the case, simply wiring the supply voltage to one of the pins on the ATMega, and only turning it high when the SD detect line is pulled low (Signalling there's a SD card there) should solve the problem.

I don't expect a SD card to require more power than the ATMega can handle.

EDIT: Looks like I was wrong. Power rating for pins is <50mA if you want to push it. SD Cards can draw >100mA - While often not the case, this is still WELL beyond what a pin can supply.

I could add in some type of switch, but I'm attempting to keep component count (and cost) relatively low. Possibly going to go with a transistor, but I've got some more research to do


Try sticking a CAP across the power lines to the SD reader, and see if that helps  :)
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Besides what spycatcher2k pointed out, there should be a 100nF decoupling capacitor next to each IC.
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter

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