Accessing UART1 Or Turning OTG into a Serial Console?

Discussion in 'UDOO NEO' started by ctassell, Nov 24, 2015.

  1. ctassell

    ctassell UDOOer

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    Hello,

    We just got our first Neos after having a few Duals and Quads to play with, and I'm having problems figuring out how to access the serial console. The webpage for the Neo says that there is a UART1 that will act as a serial console (hopefully for UBoot as well as Linux) but there is no documentation on what pins it's connected to. Is there a corresponding Udoo_pinout_diagram.pdf for the Neos? Or, better yet, is there a jumper like on the Quad/Duals that will switch the USB OTG port from an NDIS network port to a USB serial port like the old J22?
     
  2. jas-mx

    jas-mx Active Member

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    I'm surprised this question hasn't been asked earlier because the serial console is the quickest way to solve many of the problems other are having. There is no USB serial port instead you need to connect a USB to Serial adapter to pins on Connector J7.

    Pins
    2 UART1_TXD
    4 UART1_TXD
    11 or 13 GND

    Pins are 3.3v tolerant.
     
    Last edited: Nov 24, 2015
  3. ctassell

    ctassell UDOOer

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    I thought there must be some way to do it, but it doesn't seem to be working for me. I get data (just garbage) off of pins 0 and 2, but nothing off of 2 and 4. The pinouts (which, for anyone looking are in the Hardware & Accessories->GPIO part of the docs at http://www.udoo.org/docs-neo/Hardware_&_Accessories/Gpio.html) say that pins 0 and 2 are UART1_TX and UART1_RX, so I have pin 2 (RXD) of my serial adaptor going to UART1_TX (J7 pin 0) and pin 3 (TXD) going to UART1_RX (J7 pin 2) and pin 5 going to a ground.

    I'm running my terminal at 115200 8N1, but I've also tried 9600 and 38400.
     
  4. ctassell

    ctassell UDOOer

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    I booted the Neo into Linux and tried to access the same serial port (minicom -D /dev/ttyMCC) and get the same garbage chars, so I'm thinking the pinouts are correct but I just have bad wires (I'm cramming some jumer cables onto the DB9 of my USB adaptor) Thanks for the tip jas-mx, once I get some proper cabling it will make things much simpler!
     
  5. Xykon

    Xykon Member

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    It works for me, using a simple FTDI breakout board at 3.3V (115200bps). You can also order a board on the udoo shop that you can simply plug into the neo for serial console.
     
  6. Xykon

    Xykon Member

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    Umm... don't use a USB <-> RS232 cable with DB9 connector... those use 12V/-12V line voltage (instead of the required uart at 3.3V) and will most likely destroy your udoo very quickly! The best option is an ftdi breakout module where you can select between 3.3V and 5V operating mode. Make sure you select the 3.3V option as the pins on udoo are not 5V tolerant and you can quickly kill the serial port on the chip by applying too much voltage.
     
    Last edited: Nov 25, 2015
    Andrea Rovai likes this.
  7. Andrea Rovai

    Andrea Rovai Well-Known Member

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