University of Plymouth - Stages 1, 2 and 3 / Mbed OS Task531

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

main.cpp

Committer:
noutram
Date:
2015-09-24
Revision:
0:ee386c3c3a80
Child:
2:302b3ed98b81

File content as of revision 0:ee386c3c3a80:

#include "mbed.h"
//#include "spi.h"

PwmOut mypwm(PWM_OUT);

//This GPIO is used for Chip Select
DigitalOut DAC_CS(D10);

//SPI Object
SPI spi(D11, D12, D13);

//Ticker for setting the output sampling rate
Ticker t;

//Prototype for the ticker ISR
void writeSample();

int main() {

    //Set speed of the SPI interface
    spi.frequency(20000);
    
    //16 bit words, mode 0 clock
    spi.format(16,0);
    
    //Write at 1000Hz    
    t.attach(writeSample, 0.001);
    
    while(1) {
        sleep();
    }
}

//ISR for ticker
void writeSample()
{
    //Enable the selected slave device
    DAC_CS = 0;
    
    //Write a header (top 4 bits) and value (bottom 12 bits) 
    unsigned int val = 2048;
    spi.write(0x7000 | val);
    
    //Disable the selected slave device (and update the output)
    DAC_CS = 1;
}