Getting started with the TM4C Launchpad on a Linux System

This is a guide to getting up-and-running to develop firmware for the TM4C123GH6PM evaluation board from Texas Instruments on a Linux based system. The TM4C was my first microcontroller,and i found it very uninteresting to use a bulky IDE like Keil or IAR EWARM that abstracts so much from me,I checked various blog posts about using GCC and Make to develop firmware for this board,but the instructions were always outdated. The steps here are tested on an Ubuntu 18.04 LTS system,but should work on any other Linux based system

To start writing firmware for the TM4C we need:

• A text editor like vim or vscode whatever is your preference

• A compiler/assembler/linker package like gcc-arm-none-eabi

• Files specific to this board like a linker script *.ld file and a startup.c file

• A Makefile

• A flasher program,I use lm4flash in this guide,although OpenOCD may also be used

Toolchain installation

1.First we install the dependencies needed by our tool chain

sudo apt install flex bison libgmp3-dev libmpfr-dev libncurses5-dev libmpc-dev autoconf texinfo build-essential libftdi-dev python-yaml zlib1g-dev libusb-1.0-0-dev

2. Then we install the GCC for ARM package

sudo apt install gcc-arm-none-eabi

3. And finally the lm4flash flashing tool

git clone https://github.com/utzig/lm4tools.git
cd lm4tools/lm4flash
make
sudo cp lm4flash /usr/bin/

4. Next, create a file called 61.dialout.rules in /etc/udev/rules.d with this line inside it SUBSYSTEM=="usb", ATTRS{idVendor}=="1cbe", ATTRS{idProduct}=="00fd", MODE="0666" This is to allow any program to read or write to your TM4C Launchpad board,i.e you will not have to use sudo every time. Now restart your PC

Building and flashing a basic Blinky.c program to the board

I have already created a template for the TM4C,you just have to clone it from GitHub

git clone https://github.com/shawn-dsilva/tm4c-linux-template.git

This template contains a skeleton directory of folders,a blinky.c file,a startup.c file and a linker script for the TM4C

Once cloned,cd into tm4c-linux-template and run make

you can change the name of the final binary by setting the PROJECT variable in the Makefile to whatever name you want to use,by default PROJECT = main

once you run make this will be the directory structure:

├── bin
│   ├── main.bin
│   └── main.elf
├── inc
│   └── startup.h
├── ld
│   └── TM4C123GH6PM.ld
├── libs
│   └── startup.c
├── Makefile
├── obj
│   ├── main.d
│   ├── main.o
│   ├── startup.d
│   └── startup.o
├── README.md
└── src
    └── main.c

Here,

• src contains your Source files,i.e main.c
• libs contains your library source files,i.e startup.c,that are used by the main program
• inc contains your *.h Header files,like startup.h
• obj contains the *.o object files and *.d dependency files
• bin contains an ELF executable main.elf,this contains debugging symbols used by the gdb debugger,and main.bin,the final binary that is stripped off the debugging symbols and will be flashed to your board

Run make flash to invoke lm4flash and burn your main.bin binary to the board,press the RESET button on your board,and hold SW1 to cause the red LED on board to blink as long as it is pressed

Additional library and driver files for this board can be acquired by downloading the SW-TM4C-2.1.4.178.exe package from this TI Website here