Linux : Where is UART's

I'm interested in the UARTS myself.  I need RS232 support with CTS,RTS,DCD,and DTR.  Are these UARTS TTL or RS232 levels?  Is there support for the hardware control signals?

Thanks,

Chris

I'm interested in the UARTS myself.  I need RS232 support with CTS,RTS,DCD,and DTR.  Are these UARTS TTL or RS232 levels?  Is there support for the hardware control signals?

Thanks,

Chris

i don't found support with CTS,RTS,DCD,and DTR (maybe by GPIO)

however, I can confirm that the signal level is TTL for all UART

Hello,

Finaly I foud a solution to make UART 4&5 working.

I will try to write simple guide, how to achieve that.

Thanks to xizhou wang I was able to find the way how to do that.

1. In schematics http://www.element14.com/community/servlet/JiveServlet/previewBody/65504-102-1-287949/RIoTboard_Schematics.pdf on page 8 you can find how the UART 4&5 are pinned.  

So in file /linux-imx/arch/arm/mach-mx6/board-mx6dl_riot.h you have to add UART4&5

#if 0
        /* UART1 for debug */
        MX6DL_PAD_CSI0_DAT10__UART1_TXD,
        MX6DL_PAD_CSI0_DAT11__UART1_RXD,
#else
        /* UART2 for debug */
        MX6DL_PAD_EIM_D26__UART2_TXD,
        MX6DL_PAD_EIM_D27__UART2_RXD,
#endif
        /* UART3 */
        MX6DL_PAD_EIM_D24__UART3_TXD,
        MX6DL_PAD_EIM_D25__UART3_RXD,

        /********************** ADDED ***********************/
        /* UART4 */
        MX6DL_PAD_KEY_COL0__UART4_TXD,
        MX6DL_PAD_KEY_ROW0__UART4_RXD,

        /* UART5 */
        MX6DL_PAD_KEY_COL1__UART5_TXD,
        MX6DL_PAD_KEY_ROW1__UART5_RXD,
        /***************************************************/

2. Then in /linux-imx/arch/arm/mach-mx6/board-mx6q_riot.c you have to initialize UART 4&5

static inline void mx6q_riot_init_uart(void)
{
        imx6q_add_imx_uart(0, NULL);
        imx6q_add_imx_uart(1, NULL);
        imx6q_add_imx_uart(2, NULL);
         
/********************** ADDED ***********************/
        imx6q_add_imx_uart(3, NULL);
        imx6q_add_imx_uart(4, NULL);
/***************************************************/
}

And now you have to recompile the kernel and flash it to your RiotBoard.

After that you will have:

/dev/ttymxc0 - still don't know what is for

/dev/ttymxc1 - debug serial port

/dev/ttymxc2 - UART3

/dev/ttymxc3 - UART4

/dev/ttymxc4 - UART5

Hope it will help

Marek Czudek wrote:

 

/dev/ttymxc0 - still don't know what is for

it's hooked up to the OpenSDA debugger via U26 on p20 of the schematics.  Some info on OpenSDA is available here https://www.pemicro.com/opensda/ and the user guide http://cache.freescale.com/files/32bit/doc/user_guide/OPENSDAUG.pdf

It's briefly mentioned on p33 of the user manual with the note at the bottom of the page that says

The RIoTboard has hardware to support Freescale’s OpenSDA interface. Currently this

interface has not been enabled in software

so apparently ttymxc0 is unusable as the OpenSDA hardware appears to be the only way to get to it and for some unknown reason it has no software support.

Indeed, following the instructions from the OpenSDA user manual gets no response. No usb storage device appears. You'd have to assume therefore that whatever firmware is supposed to be loaded onto the Kinetis K20 is missing.  Only a guess, but loading it may take jtag onto the un-populated J17.

do you have tutorial to rebuild kernel linux for riotboard  ? or just image binary file included UART 4 & 5 ?

Here is how I compiled the older RiotBoard Kernel from the git Repo. Everthing done in a Debian Virtual Machine.

I don´t use the toolchain from the repos. because of that you have to install some essential stuff.

apt-get install git build-essential fakeroot kernel-package u-boot-tools zlib1g-dev libncurses5-dev

To get the gcc compiler with armhf put this line into /etc/apt/sources.list

deb http://www.emdebian.org/debian/ unstable main

Then type the following commands:

apt-get update
apt-get install emdebian-archive-keyring
apt-get update
apt-get install gcc-4.7-arm-linux-gnueabihf
ln -sf `which arm-linux-gnueabihf-gcc-4.7 ` /usr/local/bin/arm-linux-gnueabihf-gcc

Now you can checkout the Kernel code from git

git clone git://github.com/embest-tech/linux-imx.git -b embest_imx_3.0.35_4.1.0

At this point you can make the changes as described in this thread to activate UART 4 & 5.

Then to configure and compile everything.

cd linux-imx
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- imx6_defconfig
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- uImage

If it compiles without errors you find the images under arch/arm/boot

Tell me please if I missed something or you get any errors.

I´ve written this directly out of my head. So it could be wrong in some point.

Otto, thank you for your instructions. It was very helpful and much appreciated. Much better than using the toolchain. However, the symbolic link didn't work for me (using Debian 7.5 VM) and I had to change it to:

ln -sf arm-linux-gnueabihf-gcc-4.7 /usr/bin/arm-linux-gnueabihf-gcc

Just in case others are having the same problems I did. After that everything worked great, not only for the original kernel but also for selsinork's new u-boot and kernel. (Thank you selsinork!).