Overview

This is a quick how-to for writing a few hello-world example apps on top of the Texas Intruments Real-Time Operating System (aka. TI-RTOS with SYSBIOS kernel) and running and debugging it on the Tiva C Launchpad (TM4C123GXL) evaluation board ($13) from a Linux host without depending on the IDE from TI.

Of particular interest is the system output re-direction to UART and workarounds for a few issues in SYSBIOS code.

Example apps:

• hello: console output to UART
• hwiswitask: various threading primitives (ex. from SYSBIOS user manual)
• exception: cause a divide-by-zero and dump exception context to console

Skeleton:

• main.c : initialization of console and logger and call to app entry point
• event_logger.c : logger event formatting
• uart_iface.c : write to UART serial ports
• EK_TM4C123GXL.c : board-specific code

Most content for this how-to was gathered from various existing resources and stitched together to get an end-to-end working environment. The initiative was started when there was less support for the Tiva C Launchpad than there is now and contained more resources (e.g. linker scripts), which are no longer needed and hence have been removed.

Disclaimer: personal project, not affiliated with TI.

Tool Dependencies

• gcc-arm-none-eabi toolchain

  • Tested with v4-7-2013q3-0precise6 from Ubuntu repos
  • Prefix assumed to be /usr

• RTSC XDC Tools v3.25.05.94: standalone distribution

  • Build framework for building XDC packages and applications that comsume them. SYSBIOS and TIRTOS are collections of XDC packages.
  • Overview of RTSC and an accessible tutorial
  • Documentation for some packages here. The docs for the packages used for the present hello-world are inline in the .xdc files. They can be compiled into HTML with xdc.tools.cdoc or viewed interactive by setting up xdc.tools.cdoc.sg viewer (depends on Mozilla).
  • Note: XDC Tools v3.25.00.48 in TI RTOS distribution v1.21.00.09 suffers from Bug 421665 which prevents it from working on 32-bit Linux hosts.

• OpenOCD

  • For flashing and debugging the target via ICDI
  • Tested with v0.7.0 installed from source)
  • sudo apt-get install openocd or from source
  • Board config script included in this repo

Source Dependencies

• TivaWare v2.0.1.11577a: shipped with TI RTOS v1.21.00.09

  • Low-level support for microcontroller features.
  • Alternatively, standalone distribution: SW-TM4C Complete
  • TivaWare 1.0 or 1.1 is also included in the SW-EK-TM4C123GXL distribution, which looks superceded by the above
  • To rebuild:

  $ cd tirtos_1_21_00_09/products/TivaWare_C_Series_2.0.1.11577a/
  $ make clean # needed to clean deps files with previous build
  $ make

• ti.sysbios package v6.37.00.20 (patched): sysbios repo

  • Real-time operating system kernel.
  • Note: SYSBIOS suffers from this and this bugs, which break timers. The version in the repo has the patches.
  • Note: This version of SYSBIOS is shipped with TI RTOS distribution v1.21.00.09. Current latest version in dedicated SYSBIOS distribution is v6.35.04.50, which does not include explicit support for TM4C123, in particular default linking scripts. However it can be made to work with a hand-written linker script (see earlier commits in this repo).
  • To build:

  $ cd /path/to/sysbios
  $ make -f bios.mak XDC_INSTALL_DIR=/path/to/xdctools_3_25_05_94 \
      XDCARGS='gnu.targets.arm.M4F=/usr'

• ti.drivers package: part of TI RTOS v1.21.00.09

  • Wraps low-level microcontroller features to be used with XDC packages.

  • In tirtos repo repo there are patches to the UART code that

    • remove unneeded interrupts due to the async API, which is unused by our app
    • change the UART clock source to PIOSC to inorder to make it robust against clock changes due to transitioning into deep sleep (sleeping is not enabled by default).

    If you use that source, then see the README for build instructions, otherwise see below.

  • To rebuild:

    $ cd /path/to/tirtos_1_21_00_09
    $ make -f tirtos.mak CCS_BUILD=false GCC_INSTALLATION_DIR=/usr \
        TIRTOS_INSTALLATION_DIR=$PWD \
        XDCTOOLS_INSTALLATION_DIR=/path/to/xdctools_3_25_05_94 \
        BIOS_INSTALLATION_DIR=/path/to/sysbios \
        drivers

• ti.uia.* packages v1.04.00.06: shipped with TI RTOS v1.21.00.09)

  • Instrumentation functionality, of which the Logger framework is used here

  • To rebuild:

    $ cd /path/to/tirtos_1_21_00_09
    $ make -f tirtos.mak CCS_BUILD=false GCC_INSTALLATION_DIR=/usr \
        TIRTOS_INSTALLATION_DIR=$PWD \
        XDCTOOLS_INSTALLATION_DIR=/path/to/xdctools_3_25_05_94 \
        BIOS_INSTALLATION_DIR=/path/to/sysbios \
        uia

Build, Flash, and Run

Setup pointers to the above dependencies

$ export XDCTOOLS_INSTALLATION_DIR=/path/to/xdctools_3_25_05_94
$ export TIVAWARE_INSTALLATION_DIR=/path/to/tirtos_1_21_00_09/products/TivaWare_C_Series_2.0.1.11577a/
$ export BIOS_INSTALLATION_DIR=/path/to/sysbios
$ export TIRTOS_INSTALLATION_DIR=/path/to/tirtos_1_21_00_09/
$ export UIA_INSTALLATION_DIR=/path/to/tirtos_1_21_00_09/uia_1_04_00_06

The default target builds all example applications:

$ cd /path/to/tivaapps
$ make
$ openocd -f openocd.cfg 'program app_hello.out 0x00000000'

The Tiva C board should create a USB-to-Serial device linked to the UART Port 0. To see the console output:

$ screen /dev/ttyACM0 115200

and push the reset button on the board.

For reference, the driver (kernel module) for the USB-to-Serial device is cdc_acm. Output of lsusb:

Bus 004 Device 010: ID 1cbe:00fd Luminary Micro Inc.

and dmesg:

[487894.788077] usb 4-1: new full-speed USB device number 10 using uhci_hcd
[487894.949990] cdc_acm 4-1:1.0: This device cannot do calls on its own. It is not a modem.
[487894.950031] cdc_acm 4-1:1.0: ttyACM0: USB ACM device

Debug

$ openocd -f openocd.cfg
$ gdb
gdb> target remote localhost:3333
gdb> monitor reset halt
gdb> break app
gdb> c

Across re-flashes, the gdb session can be left running, but it should be detached. Once detached, openocd demon can be shutdown, binary flashed, demon restarted, and gdb target command re-run. Without detaching, the gdb session seems to break in odd ways.

Add another application

Create an app_name.c with app as the main function, analogous to app_hello.c. In Makefile add the file to APPS variable and add a corresponding target below # Applications.