Step 1. Type in the following program in text editor like gedit or kedit and save it as hello.c

#include <nuttx/config.h>
#include <stdio.h>

int app_main(int argc, char *argv[])
{
        printf("Hello, World!!\n");
        return 0;
}

Step 2. Open a terminal, switch to the folder containing the C file and compile it using the following command.

$ flags=$(nuttx-config --cflags --libs zkit-arm-1769)
$ arm-none-eabi-gcc hello.c $flags -o hello.elf
$ arm-none-eabi-objcopy hello.elf --target=ihex hello.hex

Step 3. Fix the errors, if any and check the folder for the executable file hello.hex

Step 4. Connect the development kit to the PC, through the USB-UART mini connector. Press the PROG button, to switch into Programming Mode. (PROG LED On)

Step 5. The board will be detected as a USB serial device. The device file name can be obtained from dmesg. The device file name is usually /dev/ttyUSB0 or /dev/ttyUSB1.

The .hex can be flashed using the lpc21isp command. The general syntax of the command is given below.

lpc21isp -control <hex-file> <serial-device> <baudrate> <osc-freq>

The command for programming the hello.hex file onto to the ZKit-ARM-1769 board is given below.

$ lpc21isp -control hello.hex /dev/ttyUSB0 115200 12000

Step 6. Press the PROG button, to switch into Serial Communication Mode. (PROG LED Off)

Open picocom, and specify 115200 baudrate, 8 data bits, no parity, 1 stop bit, using the following command. When done, use Ctrl-A Ctrl-X to exit picocom.

$ picocom -b 115200 /dev/ttyUSB0

Press the RESET button, to execute the downloaded program. The "Hello World" message should get displayed on the serial terminal.