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the flight controller i am using is a custom one, which is a teensy 4.0 microcontroller. it cannot have more than 3.3V into its GPIO pins. I know I can use the 5V from the BEC of the ESC to power my teensy, but will the digital control pins from the ESC apply more than 3.3V at the pins of the teensy?

this the drone motor (and frame) that i am using.

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As you point out, the Teensy 4.0 online documentation mentions that neither the digital GPIO nor analog I/O are 5v-tolerant pins. It appears that the ESCs in the kit you linked to only have a PWM signal input and no bi-directional communication bus (e.g. Bidirectional DSHOT), so the only voltage present on the PWM input line would be one that you create. (thus there is no real danger of the ESC putting 5v on the signal line, though the 5v BEC pin will still have it)

However, you may run into another issue when trying to issue commands to the ESC from the Teensy. Being a 3v3 logic-level device, its logic high may not be sufficient voltage to "trigger" the ESC, depending on how the ESC's software interprets incoming signals. You can address this with a "level converter" (essentially just a set of small BJT transistors to switch 5v lines with 3v3 ones and vice versa) like this one from Amazon.

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  • $\begingroup$ thanks! actually the teensy flight controller code i am using is made to work with the Oneshot protocol and PWM for the ESCs. so hopefully that won't be a problem. i have been trying to test some bidirectional logic converters that i have but i have had no luck. if you have a good link/video that shows how to test/use them correctly, please let me know! $\endgroup$
    – Ahmed Anwer
    Commented Jun 10, 2021 at 1:37
  • $\begingroup$ Oh, got it! Oneshot is also a uni-directional protocol, so there shouldn't be any dissimilar issues to the PWM things I mentioned in my answer. Best of luck for the project! $\endgroup$
    – ifconfig ♦
    Commented Jun 10, 2021 at 2:42
  • $\begingroup$ Could you clarify what exactly you mean by "bidirectional logic converter"? $\endgroup$
    – ifconfig ♦
    Commented Jun 10, 2021 at 2:42
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    $\begingroup$ the one you sent are bidirectional logic converters, they are the ones used for I2C when micro controllers of different logic levels are trying to exchange data. i think they can be used for unidirectional purposes as well. i found a stackexchange post on electrical engineering for it actually, so i will use that! thanks tho! $\endgroup$
    – Ahmed Anwer
    Commented Jun 10, 2021 at 7:06
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    $\begingroup$ Nice answer! Most likely the ESC will accept 3V3 inputs anyway; they are usually STM-based, and the thresholds are hardware, not software dependent. according to this answer 3.3v should be registered as high even if the MCU is powered from 5V. Unless the ESC has an optocoupler on the data lines, in which case all bets are off. $\endgroup$
    – FlashCactus
    Commented Jun 15, 2021 at 15:33

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