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Thread: Teensy 4.1 and HC-05

  1. #1
    Junior Member
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    Aug 2020
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    Teensy 4.1 and HC-05

    Hi everyone,

    I am pretty new to teensy and I just tried to connect my teensy 4.1 to an HC-05 to connect it to my android. I am using the app "Arduino BlueControl." I connected RX to pin 7 and TX to pin 8 (I also tried the reverse), but I am getting no response on the app terminal. Here is my test code. Any help would be appreciated.

    Yehuda Tager

    void setup() {
    Serial2.begin(9600);
    }

    void loop() {
    Serial2.println("hello");
    delay(100);
    }

  2. #2
    Senior Member PaulS's Avatar
    Join Date
    Apr 2015
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    Netherlands
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    Hi Yehuda,
    Just checked your code on a Teensy 4.1 & HC-05 module and it is working fine.
    Teensy pin 7 connects to HC-05 pin TXD, pin 8 to pin RXD.
    Do you power the HC-05 by 3V3 like I did? And did you pair it?
    Does the LED flash on your HC-05 module?

    Here is my setup and Android terminal program output:

    Click image for larger version. 

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    Click image for larger version. 

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    Paul

  3. #3
    Junior Member
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    Aug 2020
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    Thanks so much for helping me out. Yes I did power the HC-05 with 3.3 volts (from the output of the teensy, so it should be regulated nicely). The light was blinking with 2 quick flashes, then a pause. What does pair it mean? The app on the phone did say that it was connected to HC-05.

  4. #4
    Senior Member PaulS's Avatar
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    Apr 2015
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    Netherlands
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    With pair I meant Bluetooth pairing. But you did that obviously.
    The 2 quick flashes are shown when a program connects to the HC-05 module.
    Perhaps you should try the app I used? Serial Bluetooth Terminal

    Paul

  5. #5
    Junior Member
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    Aug 2020
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    It is working now. Thank you so much for your help.

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