8 Replies Latest reply on Jul 4, 2014 7:48 PM by DinoT_Intel

    Accessing the UART Port of Galileo



      Does anyone have any idea how can we access the UART port (the one which is connected using 3.5mm jack) on the Galileo board. From the previous posts on the forum, what I gather is that Serial and Serial1 are not mapped to this port. Serial2 is inaccessible. Then how do we reference this port?

        • 1. Re: Accessing the UART Port of Galileo

          Hi rkt_kgp


          The UART for the 3.5 connector is the /dev/ttyS1, but I’m not aware if you can use this port on something different than accessing the Linux console.



          • 2. Re: Accessing the UART Port of Galileo

            JPMontero_Intel is right, I think it would be easier for people to suggest a solution to you if you could elaborate on what exactly are you trying to achieve.

            • 3. Re: Accessing the UART Port of Galileo

              On a future release of the IDE (w/ Gen2 support), it can be supported.

              I can add it in by default if there is enough demand for it.


              It will not be routed for to any of the Arduino pins but you can send/receive data to the 3.5mm connector.

              You would also lose your console until you call Serial2.end();

              • 4. Re: Accessing the UART Port of Galileo

                AlexT_Intel I want to be able send and receive data through this UART. I have connected it to a RS232 to USB connector and I get the output on the other side by connecting a USB cable b/n my PC and the USB port of the connector.I want to receive data on the Galileo through this UART whenever I send something from the other side and vice-versa.


                I am able to do this using the digital pins 0 and 1 present on the Galileo which is mapped by Serial1. Moreover, I'm using Windows OS.So, kindly let me know in that context as to if it is possible to send/receive data through the above mentioned USB port. If it is possible, how do I reference it in my code?

                • 5. Re: Accessing the UART Port of Galileo

                  Presently when I am booting up the board with the SD card(Linux included), and connect the 3.5 mm jack to the UART port, I receive junk values on the other end.

                  The UART port is connected to a RS232 to USB converter. The USB port is then connected to a PC. Using a serial console software such as X-CTU,Tera Term or PuTTY, I am trying to read the bits. But all I get are junk values. Is this expected? Kindly help.

                  • 6. Re: Accessing the UART Port of Galileo

                    no, it's not expected. Possibly your settings are incorrect. If you haven't changed the settings on Galileo - those are the settings I use for PuTTy: 


                    data bits=8

                    stop bits=1


                    flow control=XON/XOFF (works for me - if it doesn't work you might have to switch off)


                    Maybe your cable is broken such that you can't run 115k?

                    • 7. Re: Accessing the UART Port of Galileo

                      Yeah, that looks like a cable problem - there were similar posts earlier in this community when people were making their own cables and either incorrectly connected the contacts or had soldering problems (esp. with the ground). So I'd start with double-checking your cable or replacing it with another one.


                      Now, as far as the code is concerned, this port is used by Linux console in the default setup and there's no binding in the supplied Arduino emulation layer (I presume by "my code" you mean the one you write in teh Arduino IDE). So it will be not that straightforward task to use it for data exchange - Linux will be interferring. You'll need to reconfigure Linux to not use it, then you should be able to use it, but still not by using Arduino's Serial* objects, you'll need to use generic Linux approach to that.

                      • 8. Re: Accessing the UART Port of Galileo

                        Withe latest Galileo IDE release 1.0.2, Serial2 is now supported.

                        It is routed to where the 3.5mm audio jack is.

                        Using Serial2 will cause you to lose your Linux console, until Serial2.end is called()