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Thread: How to connect Teensy 4.0, HC-05 and MPU9250

  1. #1
    Junior Member
    Join Date
    Apr 2020

    How to connect Teensy 4.0, HC-05 and MPU9250


    i am wondering if someone tried using Teensy and Bluetooth module HC-05? I want to read the values from accelerator sensor MPU9250 and send them via
    Bluetooth but the module HC-05 actually runs with 3,6-6V and the Teensy 4.0 supports only 3,3V.

    Any ideas?

    This is my wiring so far:

    Click image for larger version. 

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    The power source is the USB. I somwhere read "in the internet" that it should be possible to use only 3,3V but i want to be sure before buying the components.

    Thx a lot.

  2. #2
    I've also seen posts that for HC-05 3V3 should be enough. NCS, SDA, SCL pullups for the MPU9250 are on the module, I guess?

    If I was you I would always foresee the ability to power cycle those modules from the Teensy. I guess the draw of the MPU9250 is low enough to simply provide VCC directly from a Teensy port -- but if it's a module check for an additional LED. For the supply of the HC-05 you would need a transistor (or a separate LDO with EN input) in between the module and the power control port.

    You don't need the INT from the MPU9250 nor the EN from the HC_05?

    Kind regards,

  3. #3
    Join Date
    Feb 2020
    Dublin, Ireland
    I've used a HC-05 connected to a Teensy 3.6 and powered directly from VIN (5V). The logic pins are 3.3 V. Some HC-05 modules have a button for forcing them into AT mode - that will make life easier for you. You can leave EN floating.

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