Simple Embedded System Project

Objective

Work together as a class to create a wireless network of interactive devices. An example would be one controller responsible for lights, another controller responsible for motion sensor, and a central control can interact with these controllers to perform tasks such as turning on lights when motion has been detected.

Structure

There are minimum four nodes to be designed by a team of 10. Each team is then split into smaller sub-team for the design of each of the four nodes. Each team of 10 will also compete with the other teams in your class and your grade will be assigned relative to each other with the best team earning the best grade.

Example Nodes

The nodes listed below are just examples. You can and should create your own node with its own purpose that goes above and beyond the examples listed in this article. Four unique features are required per node, and some hints are provided in the latter part of this document.

Lights Node

This node shall act like a wireless node that is responsible to turn on and off lights. This will involve some hardware design such that you can connect your board to some high-power LEDs. Look-up “super bright led” at sparkfun.com for examples.

Sensor Node

This node shall act like a sense point for the commander node. The objective is not just to provide the on-board sense points such as temperature and light, but also implement features such that you can report other creative sense points such as a motion sensor, and distance sensor.

Commander Node

This node shall be responsible to put it all together and serve as a single commanding node to get sensor input and control the lights. This node shall provide the interface for the user, so try to provide user options to configure features such as automatic lights, or remote controlled operation.

Challenges

Over the course of the project, you will encounter some real-world problems such as :

• How will you design your project to be user friendly?
• How will you collaborate in your large team?
• How will you balance your budget and keep parts cost to a minimum?
• How will you design your network protocol such that each team understands a command and response system well?
• How will you make your project more creative? How will it stand out?
• What if you command a light output node that is not responding?

  How will you report this to the user and what would you do?

Sample Code

Light Sensor Node

#include "mesh.h"
#include "nrf_driver.h"

void process_command(char command);

int main(void)
{
    char our_addr = 100;
    mesh_set_node_addr(our_addr);

    while (1) {
        /* Check if we get a packet within 1 second : */
        mesh_packet_t wireless_pkt;
        if (nrf_get_pkt_received(&pkt, 1000)) {
            /* Assuming first data byte is our command: */
            process_command(pkt.data[0]);
        }
    }
    return 0;
}

void process_command(char command)
{
    enum {
        lights_on = 1;
        lights_off = 2;
    }

    switch(command) {
        case lights_on:
            /* TODO Turn on lights */
        break;

        case lights_off:
            /* TODO Turn off lights */
        break;

        default:
            /* TODO Take action for invalid command */
        break;
    }
}

Commander Node

#include "mesh.h"
#include "nrf_driver.h"

int main(void)
{
    /* Same enum as lights controller */
    enum {
        lights_on = 1;
        lights_off = 2;
    }

    char our_addr = 200;
    char lights_addr = 100;
    mesh_set_node_addr(our_addr);

    while (1) {
        /* Turn lights on/off every 3 seconds */
        char cmd = 0;

        cmd = lights_on;
        mesh_send(lights_addr, mesh_pkt_ack, &cmd, 1);
        /* TODO Check if we got an ACK */
        delay_ms(3000);

        cmd = lights_off;
        mesh_send(lights_addr, mesh_pkt_ack, &cmd, 1);
        /* TODO Check if we got an ACK */
        delay_ms(3000);
    }
    return 0;
}