ESC Boot mode?

Stefan Amundarain

Good day,

Just received a new batch of the 4-in-1 FPV ESC’s and had a weird boot up with the first one I tried.

The power out for the voxl also is not staying at 5v and is fluctuating between 1v and 5v when measured with a multi-meter.

Any fix for this? Is this a boot up sequence? We have not faced this before today. This is a brand new ESC that is on its first power up.

Link to video:
https://drive.google.com/file/d/1BhnvUNBwsZ-l2p2VrkCFHZtQENIuKfLA/view?usp=drivesdk

Alex Kushleyev

Hi @Stefan-Amundarain,

Thanks for sharing the video. A few comments and questions:

The fast blinking after power is applied is the bootloader signaling that it has loaded and is waiting to see if there is a firmware update
The bootloader times out after 1 second and starts executing firmware, if there is valid firmware. The bootloader does not make any beeps. If there is no valid firmware, the ESC (channel) will stay in bootloader and will blink continuously (fast, about 5hz, the same rate as during initial 1 s).
In your case, the firmware is valid on all 4 channels and the fast blinking stops after 1 second and firmware loads. The firmware does start and makes a short beep.
However, after the beep, there should also be a 2 slower LED flashes, controlled by the firmware (you can check that on a working ESC). I do not see it here, so it looks like something bad happens right after the motor beep.
I see that you are using metal nuts to fasten the ESC to your frame, however there are some test points that are very close (top right corner). It is possible that the metal nuts or standoffs on the other side are touching a component or a test point.
also, what is actually powering the ESC, is it a power supply or a battery? If you have a power supply which can display current draw, i would recommend setting the voltage to 16V or so, and look at the power draw as this "cycling" occurs. Please note that using power supply for motor testing is not recommended due to potential voltage spikes due to regenerative braking : more infor here, however for a smoke test, a power supply works well.
the fact that 5V is sagging (this is 5V 6A !!) potentially means that there is an upstream power supply issue (related to the question what are you using to power the ESC) Or there could be a 5V (almost) short, which causes the 5V regulator to enter over-current mode. The 5V power supply feeds into 3.3V LDO regulator for the ESC MCUs, so if there is an issue with 5V, the ESC will be affected. Please make sure that there is nothing connected to the 5V and inspect area around 5V regulator for any damage. You can reference the component diagram from here - area labeled as VOXL PWR Regulator right next to the array of bulk caps in the middle of the ESC

The ESCs are fully flashed and spin tested during production, so something potentially happened afterwards.

To summarize..

please unmount the ESC from the standoffs and inspect for damage, try to apply power again if there is no visible damage
try using a power supply to measure the current during these cycles. The steady state current draw should be about 0.02-0.03A at 16V (depending on whether LEDs are blinking, etc)
inspect the ESC PCB around the 5V regulator

Please let me know if you discover anything else unusual and we will go from there! Thanks!

Alex