3 Replies Latest reply on Oct 14, 2014 5:50 PM by create

    Ubuntu Linux UART3 issue

    omeier

      The UARTS of the RIoTboard mapped as:

      -  /dev/ttymxc0     probably OpenSDA

      - /dev/ttymxc1     Debug port

      - /dev/ttymxc2     UART3

      This was also discussed here: Linux : Where is UART's

       

      So it should be possible to use the UART3 from command line with the following commands:

       

       

           configure:   stty -F /dev/ttymxc2 11125

           transmit:     echo Hello World > /dev/ttymxc2  

           receive:      cat /dev/ttymxc2

       

       

      I have discovered that UART3 is is not working in the Ubuntu build "image_SVN2591_001".

      UART3 seems to accept the data, but there is no signal on the expension port. It seems that UART3 is just not mapped to the expansion port.

      This image comes with Kernel 3.0.35-02881-g2ca0807-dirty.

       

      Then I made a downgrade to Kernel 3.0.35-02871-ga35ffe3 (image_SVN2487).

      -> With the older Kernel UART3 works as expected!

       

      Does someone know the difference between the 2 kernels?

      Is it possible to get UART3 in Kernel 3.0.35-02881-g2ca0807-dirty to work?

       

       

      This is the full kernel-version:

      Linux version 3.0.35-02881-g2ca0807-dirty (luofc@embest-tech) (gcc version 4.6.2 20110630 (prerelease) (Freescale MAD -- Linaro 2011.07 -- Built at 2011/08/10 09:20) ) #2 SMP PREEMPT Fri Apr 4 10:59:35 CST 2014

       

      and

       

      Linux version 3.0.35-02871-ga35ffe3 (luofc@embest-tech) (gcc version 4.6.2 20110630 (prerelease) (Freescale MAD -- Linaro 2011.07 -- Built at 2011/08/10 09:20) ) #1 SMP PREEMPT Wed Oct 30 15:27:47 CST 2013

        • Re: Ubuntu Linux UART3 issue
          tushar panda

          there may be a commit mismatch in the releases.

          let me check ..

          • Re: Ubuntu Linux UART3 issue
            tushar panda

            pinctrl_uart3_3   seems   to be a better option for uart3.

             

            pinctrl_uart3_3: uart3grp-3 {
                                    fsl,pins = <
                                            MX6QDL_PAD_EIM_D25__UART3_RX_DATA 0x1b0b1
                                            MX6QDL_PAD_EIM_D24__UART3_TX_DATA 0x1b0b1
                                            MX6QDL_PAD_EIM_D23__UART3_CTS_B   0x1b0b1
                                            MX6QDL_PAD_SD3_RST__UART3_RTS_B   0x1b0b1
                                    >;

              • Re: Ubuntu Linux UART3 issue
                create

                This is what I am getting now with: pinctrl_uart3_3.  Looks like  3_2 will have the same problem.

                 

                Jan  1 00:00:05 ubuntu-armhf kernel: imx6dl-pinctrl 20e0000.iomuxc: pin MX6DL_PAD_EIM_D25 already requested by 20e0000.iomuxc; cannot claim for 21ec000.serial

                Jan  1 00:00:05 ubuntu-armhf kernel: imx6dl-pinctrl 20e0000.iomuxc: pin-90 (21ec000.serial) status -22

                Jan  1 00:00:05 ubuntu-armhf kernel: imx6dl-pinctrl 20e0000.iomuxc: could not request pin 90 on device 20e0000.iomuxc

                Jan  1 00:00:05 ubuntu-armhf kernel: imx-uart 21ec000.serial: Error applying setting, reverse things back

                Jan  1 00:00:05 ubuntu-armhf kernel: 21ec000.serial: ttymxc2 at MMIO 0x21ec000 (irq = 60) is a IMX

                Jan  1 00:00:05 ubuntu-armhf kernel: serial: Freescale lpuart driver

                 

                From looking at the riot dts it looks like EIM_D25 is in use for the touch screen controller in iomuxc:

                    /* ads7846 */

                    MX6QDL_PAD_EIM_D24__GPIO3_IO24 0x80000000

                    MX6QDL_PAD_EIM_D25__GPIO3_IO25 0x80000000

                I have no need for a touch screen controller.  Is it ok to comment those lines out? I know it will break the touch controller.  Or is there a better way to disable it?

                 

                PS sorry about the multiple IDs.  Just had support delete the other account but it looks like the messages posted with the other ID are gone.