Worksheet.md

In our First Task we are going to make use of the Simulator to read from a Sensor

Simulator: Starting Point

#include "mbed.h"
#include "mbed_events.h"
#include "Sht31.h"

// An EventQueue is a very useful construct in Mbed OS, it allows you to schedule events
// and to defer from one context to another (e.g. from ISR to normal thread) without
// writing your own state machines, and while maintaining context.
// https://os.mbed.com/docs/v5.6/tutorials/the-eventqueue-api.html
EventQueue queue;

DigitalOut led1(LED1);
DigitalOut led2(LED2);

InterruptIn btn(BUTTON1);

//Setup the Sensor
Sht31 sht31(I2C_SDA, I2C_SCL);

void blink_led() {
    led1 = !led1;
        float temp = sht31.readTemperature ();
    float humidity = sht31.readHumidity();
    printf("Temp  %.2f  Humidity  %.2f\n", temp, humidity);
}

// This does not run in an ISR, so it's safe to use `printf` or other blocking calls
void btn_handler() {
    printf("Button Pressed\n");

    led2 = !led2;
}

int main() {
    // Schedule an event to run every second
    queue.call_every(1000, &blink_led);

    // Normally code in the `fall` handler runs in an ISR,
    // but you can directly defer it to the thread that runs the queue
    btn.rise(queue.event(&btn_handler));

    // Because the simulator does not support multiple threads,
    // we have to call dispatch_forever from the main thread.
    // Typically you'd run this on a separate thread within Mbed's RTOS.
    queue.dispatch_forever();
}

Simulator Task:

• Get the Sensor to read and print the temperature value when the button is pressed
• Store the Periodic Readings in Global Variables (no threads so no need to lock)
• Create a new event that runs every 0.5 Seconds
  • Check the Temperature reading, and do something if it is above 30C
  • Check the Temperature reading, and get an LED to blink if it is below 5C (you will need to trigger a new event)

Using the On Board Accelerometer:

The Discovery board has an On board accelerometer.

• https://os.mbed.com/users/grantphillips/code/LIS3DSH/docs/tip/classLIS3DSH.html

To get this working we first need to install the relevant Libaries to platform IO

• In the Homepage
  • Libaries window
  • Search and Install the relevant Libary

Accelerometr: Starting point

#include "mbed.h"
#include "mbed_events.h"
#include "LIS3DSH.h"

//Leds for Debugging
DigitalOut led1(LED1);
DigitalOut led2(LED2);

//Hopefully Serial
Serial uart(PC_6,PC_7);

//Setup Accelerometr
LIS3DSH acc(PA_7, PA_6, PA_5, PE_3);

//Thread for our event loop 
Thread eventThread;
//Event Loop itself
EventQueue theQueue(32 * EVENTS_EVENT_SIZE);

//Function to read the values
void readValues(){
    led2 = !led2;
    int16_t X, Y, Z;
    acc.ReadData(&X, &Y, &Z);           //read X, Y, Z values
    uart.printf("X: %d Y: %d Z: %d", X, Y, Z);
}

int main(){
    //Hopefully
    uart.baud(9600);
    uart.printf("Testing\n");

    //And setup event Queue
    eventThread.start(callback(&theQueue, &EventQueue::dispatch_forever));
    theQueue.call_every(1000, &readValues);

    while(1){
        //Standard Blinking, Let me know things are alive
        led1 = !led1;
        wait(1.0);
    }
}

TASK

• Using the Previous task as a Guide
  • Take a reading every 0.25 Seconds
  • Store the readings in a relevant object
  • Check the Values of the X and Y Axis every second
    • Light the Relevant LED's to show which way the board is facing
  • Print a Debug message Every Second.