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Thread: FONA Feather to teensy 3.2?

  1. #1
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    FONA Feather to teensy 3.2?

    The plan is to drive a touchscreen with a Teensy 3.2. Then, use the same Teensy as a master to a FONA Feather. I have most of my software working on both ends. I can send and receive text messages using the Feather hooked to the serial monitor while on my computer. I have a full-on keyboard and text editing/viewing stuff running on the Teensy. Its time to hook the two together and.. I'm kinda' nervous about this bit. Can I just hook tx->rx both ways and I'm good to go? What pins should I use on the teensy? Is there some that are better choices than others? Will I need to use Software serial? Or will the built in stuff work?

    I see Serial ports 1,2,3 on my Teensy card. I'm going to default to hooking things up at serial port 1..

    Any handy pointers to this kind of info? I've got all night to read.

    Sorry but this is a weird gap in my experience.

    Thanks, millions!

    -jim lee

  2. #2
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    If you already have serial parsing sorted then you use serial one on pins 0&1, I think that the Fona is 3.3V logic but would be wise to confirm then have a look in the teensy examples for the serial echo one that sends data to and from the USB and hardware serial ports and strip out the local echo lines and you should be able to test things typing into the serial terminal and running USB-teensy-HardwareSerial-Fona and back.

    You do not need software serial since there are 3 hardware serial ports on the Teensy and there is a massive CPU overhead on running software serial.

    There are other ways to connect two CPUs together that potentially leverage more of the onboard hardware and presence of a clock for higher data rates and less overhead (i2c/SPI) but for this case breaking all your existing work seems wasteful.

  3. #3
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    Well they are both set at 115200, I triple checked the wiring and they are according to the diagrams online.

    teensy TX P1 -> Feather RX P20
    teensy RX P0 <- Feather TX P21

    Each one works as per design to the serial monitor. The Feather has a crude command parser in it for testing the cell phone stuff. The teensy has a screen and keyboard that echo's what it sees from the serial monitor.

    How do I specify TX1 as opposed to TX2?

    -jim lee

  4. #4
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    make sure you have a common ground between both mcus. You will be using Serial1 on teensy pins 0&1, so you can call it to configure it

    Serial1.begin(115200);

    Serial1.println(“Hello World”);

  5. #5
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    Serial1 ?! Well that's good to know. Thanks for that!

    We'll see if that helps.

    -jim lee

  6. #6
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    Dec 2016
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    So it was switching over to Serial 1 then lowering the baud rate to 9600. Then it seems everyhting works.

    THANK YOU!!

    -jim lee

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