Development Concepts

Every software for the Jennisense consists of two parts. The hardware platform and the application.

Hardware platform

The hardware platform includes the sensor definitions, the pin mapping for the sensors and the configuration for contiki. Existing hardware platforms can be found @ JENNISENSE_PATH/contiki-jn51xx/platform/. For example the jndevkit (Jennic demo board).

Application

The application contains the contiki processes, which can use the defined sensors of the hardware platform. Existing applications can be found @ JENNISENSE_PATH/applications/. An application is independent of the hardware platform and can be compiled for each one, as long as the necessary sensors are available.

Compilation

After the toolchain is installed as described in the getting started, an application can be compiled by following steps.

cd JENNISENSE_PATH/applications/ethbridge
make TARGET=jnusb ethbridge.u

The TARGET defines the used hardware platform. Make will compile the application and uses jenprog for serial programming. If another programming method is needed you can use following commands.

make TARGET=jnusb ethbridge
ba-elf-objcopy ethbridge.jnusb -O binary ethbridge.jnusb.hex

The resulting HEX file can be used with jenprog.

Application development

A basic application has following design:

#include "contiki.h"
#include "dev/leds.h"

PROCESS(basis_process, "basis process"); //process definition
AUTOSTART_PROCESSES(&basis_process); //processes wich will be executed at startup

PROCESS_THREAD(basis_process, ev, data) //process implementation
{  
  PROCESS_BEGIN();
  PROCESS_PAUSE();
  while(1)
  {
    PROCESS_YIELD_UNTIL(ev == PROCESS_EVENT_POLL);
    //do something
  }  
  PROCESS_END();
}

AUTOSTART_PROCESSES can contain more then one process for example: AUTOSTART_PROCESSES(&basis_process, &another_process);

Sensors

Here a simple example of a process, which is using the button sensor. The button is checked every 100ms. It is important that process objects are static. Otherwise it won't work. The function sensors_find(SENSOR_NAME) returns a handle to the sensor. With the handle, the sensor can be configured and used.

PROCESS_THREAD(sensor_process, ev, data) 
{
  static struct sensors_sensor *button_sensor; //sensor object
  static struct etimer et; //timer for yield
  PROCESS_BEGIN();
  PROCESS_PAUSE();
  button_sensor = sensors_find(BUTTON_SENSOR); //get handle of sensor
  button_sensor->configure(SENSORS_ACTIVE, 1); //activate sensor
  etimer_set(&et, CLOCK_SECOND/10);
  while (1)  
  {
    if (button_sensor->value(0)) //read sensor
    {
      //button is pressed
    } 
    etimer_reset(&et);
    PROCESS_YIELD_UNTIL(ev==PROCESS_EVENT_TIMER);
  }
  PROCESS_END();
}

Makefile

CONTIKI_PROJECT = main
all: $(CONTIKI_PROJECT)
CONTIKI_TARGET_SOURCEFILES = *additional sourcefiles*

UIP_CONF_IPV6=1
DEFINES=WITH_UIP6

CONTIKI = ../../contiki-jn51xx
include $(CONTIKI)/Makefile.include

CONTIKI_PROJECT must define the main C source file. Additional source files can be defined with CONTIKI_TARGET_SOURCEFILES.