William Marsh / Mbed OS DACandticker_sample

Lab 3 example 2, no debugging

Fork of DACandticker_sample_with_debug by William Marsh

DAC Ticker

  • Sample code for part 2 of lab 3 using the DAC, called from a Ticker.
  • Note that to use AnalogOut from the Ticker (an ISR), we create a version without locking.

main.cpp

Committer:
WilliamMarshQMUL
Date:
2019-01-23
Revision:
3:2bf79a3c3cbc
Parent:
2:e27fd3b65155
Child:
4:75ad475aff41

File content as of revision 3:2bf79a3c3cbc:

// Lab 3 Example Program 2
// -----------------------
// Periodically write to the AnalogOut to create a sine wave
// Alternate between two fixed frequencies every 5 sec
//
// Updated for mbed 5

// THIS VERSION HAS NO DEBUGGING CODE

#include "mbed.h"
#include "sineTable.h"

Ticker tick ;          // Creates periodic interrupt
AnalogOut ao(PTE30) ;  // Analog output

// Function called periodically
// Write new value to AnalogOut 
volatile int index = 0 ; // index into array of sin values
void writeAout() {
    ao.write_u16(sine[index]) ;
    index = (index + 1) % 64 ;   
}

// Control the frequency of updates
//   Alternative between two frequencies      
int main() {
    int update_us = 1000 ; // 1ms
    while (true) {
        tick.attach_us(callback(&writeAout), update_us); // setup ticker to write to AnalogOut
        wait(30.0) ; // wait 30 sec 
        update_us = 2000 ; // 2ms
        tick.attach_us(callback(&writeAout), update_us); // setup ticker to write to AnalogOut
        wait(30.0) ; // wait 30 sec 
        update_us = 1000 ; // 1ms
    }
}