32u4 enters recovery mode on power up

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soofle616
 
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Joined: Fri Feb 05, 2016 4:42 pm

32u4 enters recovery mode on power up

Post by soofle616 »

I have been playing around with a 32u4 basic proto for a couple weeks and have noticed some odd behavior which wasn't really a problem until now. When I apply power, it starts up and immediately starts executing the program as it should. However, when I use a small signal relay to control power from the battery, it will go into bootloader/recovery mode and then eventually time out and start running the program. This only happens when the relay is switched on, if the relay is already "on" (it's a latching relay) and I unplug/plug in the battery or any of the associated wires, it goes right into program execution. I do not have anything connected to the reset pin on the board. The tactile button used to power the relay coil is wired through a 20ohm resistor to ground so current draw should be 50mA through the 3v coil which I wouldn't expect to cause any kind of brownout condition.

Possibly related, when I single press the reset button, the device goes into the same recovery mode. According to the documentation, it appears that should only happen if the reset button is double pressed? As a final note, this board was one of the batch that was built with the charging LED installed backwards in case that batch also had some differing behavior with respect to reset and bootloading. I have corrected the LED orientation so it does work properly.

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mikeysklar
 
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Re: 32u4 enters recovery mode on power up

Post by mikeysklar »

Can you show how you have the latching relay wired up to the board? What kind of load is the relay controlling?

Generally 40mA output is the max per pin output on the 32u4's and 20mA is a more typical load.

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XRAD
 
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Re: 32u4 enters recovery mode on power up

Post by XRAD »

maybe the relay is 'bouncing' on first latch or has a short..... might try an NPN or FET or such.....to power the feather...

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soofle616
 
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Re: 32u4 enters recovery mode on power up

Post by soofle616 »

Apologies for not getting back here for so long. I found the problem. The relay wiring is a little hard to explain but in short, the flyback diodes on the relay coils were connected improperly which was allowing battery power to feed into the output of the 3v regulator. Correcting that mistake has stopped the board from entering recovery mode when power is applied to the relay "set" coil.

I'm still curious why the board enters the recovery mode with a single press of reset instead of a double press but that's not a big deal at this point. Thank you for your responses.

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