Core will not turn on after being reprogrammed


I have had 2 cores die on me tonight. When testing the circuit using the Tinker the cores work fine, I had them running for hours. When I stared to upload custom sketches onto the core the lights go out after about a half hour. I am not able to get the cores to turn back on, just a small blue light comes on. Has anyone had this issue? So far, I have gone through 3 cores like this. With only 2 left I am afraid to continue to develop on these.

The cores were powered by a bench top power supply regulated at 5v for two of the core deaths. The third core died while connected to a 12 wall wort, using a LM7805 to regulate the power down to 5v before entering the Vin.

Any thoughts or help maybe an idea on how to get these cores working again. If not thoughts on preventing this from happening again.

We are uploading code to test the DHT11 sensor.

Thank you.

Have you tried a Factory Reset?

Hold down both buttons, let go of reset, keep holding Mode button until RGB LED flashes white… then wait until you see the slow blinking blue LED. Re-enter your network credentials.

BTW, I can’t count how many times I’ve messed my Cores up… but I always get them back to running… tough little guys.

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The hard reset work ! Thank you for that advice !

Hold mode…
Tap Reset
Keep holding mode until the light is white.

I noticed that the core is running pretty hot (over 100F) when plugged into 5v usb. Is this common ? Should I regulate the voltage outside the core down to 3.3 v


I’m running a TCP Client right now pulling 1.5k of data every 10 seconds and my Core’s Wifi module is only warm to the touch… not hot at all. I would say it’s probably 100F or less.

What kind of loads do you have hooked up to your outputs or VIN or 3V3 rails?

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Just the DHT11 temp/humid sensor. Its on A1 <10ma I have 3 transistors

The circuit also has 4 transistors with a 47ohm resistor from the D0 - 3 pins.

One core runs fine, barley warm. The other core runs Hot, same circuit.

I think the 47 ohms resistors could be your problem.

If they are going from the digital output to the base of an NPN transistor, you basically have this much current flowing out of the digital output when it’s on:
( 3.3 - 0.7 ) / 47 = 55mA. The STM32 outputs are only rated for 20mA max.

Hopefully I’ve assumed the wrong circuit… but please explain how it’s all hooked up and what transistors you are using and what they go to.

My core felt like it was running warmer than I thought it should be also.

The top of the CC3000 is 111 Degrees F after running or 24 hours.

Top of the DC to DC regulator is 120 Degrees F.

It does run pretty hot because of the Wi-Fi module. It should be quite warm to the touch, but not burning.