Photon Dead and not sure why

I was controlling a stepper driver using the Particle API curl command and then the Photon just stopped responding. I checked the photon and no lights were on so i picked it up and it was extremely hot. It wont show anything now.

I am using a 4ch logic convertor to step up the 3.3v gpio pins (D0 - D2) to 5v that the stepper driver wants to see. I am using a 5v BEC to power the photon.

This is the exact code that was running on the photon:

Was this a cause of me or a faulty photon?

If there’s any chance you are powering VIN from the BEC and it’s not a very good regulated source that could have blown your 3.3V regulator. Max input on VIN is 5.5V. If the 3V3 output is not also shorted to GND, you can try powering the Photon from 3.3V on 3V3 and see if it turns on. You may have to remove the 3.3V regulator on the dead photon first if it’s shorting 3V3 to GND.

Driving a high current inductive load like a stepper motor can also wreak havoc on your power supply, inducing high voltage spikes on it… so it would be best to add a separately filtered/regulated supply for the Photon.

I’m also a bit unsure about the need for the 3.3V to 5V level shifting… if you are driving a 4 wire center-tapped stepper you typically power the center taps with 5V and pull the other 4 coil connections to ground. You can do this with a ULN2003 darlington array which can operate down to 2V inputs. The output is then pulled to ground at up to 500mA with optional built in clamp diodes (which you would tie the common cathode of to the center taps). This might not be enough current though depending on the size of your motor, which might require a motor dedicated driver.

Thanks for the tips. I just tested the photon again by supplying 3.3v to the 3v3 pin and it powered up as normal. It does not come on with the USB cable nor the Vin pin. I do have a 24v regulated power supply and the BEC is suppose to be regulated at 5v as well with a ferret ring on it. I need the Level Shifter as the Stepper driver ( needs 5v. However i did not try to give the 5v pin on the stepper driver 5v and try sending the the step pin high and low to spin the motor with just normal 3.3v high/low.

So from the above info though it does seem i blew the 3.3v regulator. I will see if i can source a new one.