Boot / bootloader behavior question

Silly question… SC20100 chip. Power it up and I have a COM port for the bootloader (did not pull LDR low). OK… Kind of unexpected, but convenient. Flash the current RC2 firmware. Deploy my app a few times (fixing bugs), then app deploy stops working because for some reason it’s in bootloader mode again.

LDR pin is floating (circuit on board, but jumper disconnected)
APP pin is floating (not connected)
MOD pin is floating (not connected)

However, the LDR pin is REALLY floating. It’s about 0.6-0.7 volts. Per the docs this should be pulled high by the internal resistor…right? Also, if I pull it high during startup it still goes into bootloader mode.

It’s like it’s really, really attached to bootloader mode now.

Any ideas? I checked the pins with a magnifier, no shorts, everything has a nice connection, etc…

And yes Gus, I know… should have built two, but I literally ran out of solder paste. Whoops :thinking:


I am guessing you have low power and while deploying your app the firmware got corrupted. Do you use a powered hub or a dedicated power source?

Good idea… I have a dedicated DC power supply, 20A. The 3.3v regulator is 1000ma and I believe I got all the capacitor placements and values correct, although I’ll double check.

On the idea of firmware corruption, I re-flashed the RC2 firmware and now it’s working again:


On further reflection I think my firmware update check method was behaving unexpectedly. That would explain this… Everything worked good until I got to the point in code where that was called.

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