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Thread: Android tablet as serial terminal - works

  1. #1
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    Android tablet as serial terminal - works

    I was surprised to find ....

    Using my (old) Android tablet. A very nice if not fast Acer. Running older version of Andriod. Too old to surf the web, too slow with today's complex web pages.

    I installed this free Android app https://play.google.com/store/apps/d...id.gousb&hl=en
    Plugged in an FTDI USB to serial cable.
    First try, it worked. No fighting, just worked. 115200 baud.

    Then, I plugged in a Teensy 3 running a program I use a lot that I normally plug into my PC and use a serial terminal program (Bray's Terminal).
    Amazing.. that Teensy 3 worked with the Android app. Two-way - I can type commands to the program running on the Teensy 3- which monitors the "Serial" USB for incoming ASCII text commands.
    That Teensy 3 software is my 900MHz radio "sniffer" - it receives (from a 900MHz RFM69 radio connected to the Teensy), decodes each packet and displays kind of like wire shark (promiscuous mode).

    I also connected the FTDI USB/Serial so the Android tablet can talk to a non-Teensy ARM M4 board with a 3.3V UART. Works too!
    And the tablet's big battery runs the Teensy 3 as well.

    So now I have another (portable) screen to use for my serial terminal. How easy does it get?
    Last edited by stevech; 01-24-2015 at 11:42 PM.

  2. #2
    Senior Member pictographer's Avatar
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    Very good to know! Thanks!

  3. #3
    Senior Member+ defragster's Avatar
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    So does my Android Phone with OTG cable. I tried the LITE/free/Ad version : "USB Serial Terminal Lite" and it worked.

    Then I bought the $2.68 Ad free "USB Serial Terminal Pro" version

    You can program a few MACRO response keys too that would be a one touch way to switch . And I installed it on my old phone from the same purchase.

    I picked up a $10 device from Newegg that does OTG, takes Micro Usb power and will run a HDD or Teensy or another Usb: "rosewill rhbm-100-u2" This would provide Teensy power for longer runs without taking the power from the 'terminal' device - when you lose the charging port to the OTG device.

    I mention this because I tried a few others apps for another device many failed - this one worked well first time with Teensy 3.1 and makes . The other free one I was using it 'Android USB Serial Monitor' - but it 'faulted' regularly on connecting, but worked.

  4. #4
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    I have that too. The author, at my request, added the ability to use fixed-width font. I use that to simplify printing out columns of data in debugging.

  5. #5
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    I wanted to exchange data via serial between teensy and android phone with an OTG cable (no bluetooth involved) and I succeeded following your advice! Thanks @defragster
    https://play.google.com/store/apps/d...n.freeusbtools

    Here is the simple code I wrote on the Teensy LC
    IDE setup to USB type: "Serial"

    Code:
    // works perfectly with Tensy LC
    // and USB Serial Terminal Lite https://play.google.com/store/apps/details?id=com.oneman.freeusbtools
    // plus an OTG cable between Teensy and Android phone
    
    const int LEDpin = 13; // Teensy LED pin = 13
    const int buttonPin = 4;
    boolean statusButton = false;
    
    void setup() {
      pinMode (buttonPin, INPUT_PULLUP); // in order to "press" the button: connect to ground
      pinMode (LEDpin, OUTPUT);
      Serial.begin(9600); // USB OTG serial com
    }
    
    void loop() {
      unsigned char inByte = 0;
      // listen to button and send to Android via OTG
      if ((digitalRead(buttonPin) == HIGH) && (statusButton == false))  {
        statusButton = true;
        Serial.write("PRESSED");
      }
      if ((digitalRead(buttonPin) == LOW) && (statusButton == true))  {
        statusButton = false;
        Serial.write("RELEASED");
      }
      // écoute OTG pour recevoir les paramètres
      if (Serial.available() > 0) {
        // read the incoming byte from OTG
        inByte = Serial.read();
        // visual check of incoming data from phone: light the in-built LED
        digitalWrite(LEDpin, HIGH);
        delay(100);
        digitalWrite(LEDpin, LOW);
      }
    }

  6. #6
    Senior Member+ defragster's Avatar
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    Very cool it still works! Not used in some time - just moved to a new phone will have to give it a function test.

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