Simple ARM example for LPC1114

My colleagues Frank Duignan and Richard Hayes have been experimenting with an ARM Cortex M0 microcontroller in a dual inline package (DIP) which can be plugged straight into a breadboard. The chip they’re using is LPC1114FN28/102, which is made by NXP and is available for less than €2. Frank spent a bit of time working out how to program the chip using a low-cost USB-to-serial converter, so the whole thing provides a micrcontroller programming setup that’s incredibly inexpensive, but quite powerful!

Following Frank’s instructions, I’ve just got my first simple flashing LED example working on the ARM LPC1114. Here’s a couple of snaps of my breadboard circuit:

The following code (filename “main.c”) is really just a stripped back version of a more extensive example Frank sent me, so I must emphasise that all credit here goes to him.

//
// main.c - Blinking LED example for ARM LPC1114
// Written by Ted Burke (based on code by Frank Duignan)
// Last updated 29-11-2013
//

#include "lpc111x.h"

int main()
{
    // Turn on clock for GPIO, IOCON and ADC
    SYSAHBCLKCTRL |= BIT6 + BIT13 + BIT16;
    GPIO0DIR = BIT8; // Make PIO0_8 an output
    GPIO0DATA = 0;   // Turn off PIO0 outputs
    
    int n;
    while(1)
    {
        GPIO0DATA = BIT8; // Turn on PIO0_8
        n=1000000; while(--n);
        GPIO0DATA = 0;    // Turn on PIO0_8
        n=1000000; while(--n);
    }    
}

I’m using the following build script (filename “build.bat”), also courtesy of Frank Duignan. Note the full path included in the linker command on line 3. If your installation directory is different from mine, you will need to modify line 3 to match your own installation folder. Note that the default installation folder may be different on other versions of Windows (note that my installation folder is under “C:\Program Files (x86)\”).

arm-none-eabi-gcc -mcpu=cortex-m0 -mthumb -g -c init.c -o init.o
arm-none-eabi-gcc -mcpu=cortex-m0 -mthumb -g -c main.c -o main.o
arm-none-eabi-ld init.o main.o -L "C:\Program Files (x86)\GNU Tools ARM Embedded\4.7 2013q3\lib\gcc\arm-none-eabi\4.7.4\armv6-m" -lgcc -T linker_script.ld --cref -Map main.map -nostartfiles -o main.elf
objcopy -O ihex main.elf main.hex

I built my program using the gcc compiler from the GNU Tools for ARM Embedded Processors. This was the version I installed (4.7 2013q3):

• https://launchpad.net/gcc-arm-embedded/4.7/4.7-2013-q3-update/+download/gcc-arm-none-eabi-4_7-2013q3-20130916-win32.exe

During the installation, the following dialog box appears. I suggest ticking the check box to “Add path to environment variable”.

I used Flash Magic to transfer the compiled program (main.hex) to the microcontroller:

• http://www.flashmagictool.com/download.html&d=FlashMagic.exe

To compile the example code above, three more files are required: a header file “lpc111x.h”, a linker script “linker_script.ld”, and a C file called “init.c” which contains initialisation code for the ARM. All three files can be downloaded (along with lots of other useful info) from Frank’s web page. Alternatively, a quick way to get all three is to download this zip file (I just zipped the three files with Frank’s permission – thanks Frank!).

So, before building the program, my project folder contained the following five files:

Then I built the program by running the batch file build.bat.

After building, the project folder contained the following files:

Finally, I transferred the compiled program (“main.hex”) to the LPC1114 using FlashMagic.