Natalia Govor / Mbed OS lab3_DAC

Digital to analog conversion. Reads analog signal (voltage) and depending on it, sets the frequency to produce the analog output for sine wave.

Fork of DACandticker_sample by William Marsh

main.cpp@1:18e0f8aef32f, 2017-02-01 (annotated)

Committer:
WilliamMarshQMUL
Date:
Wed Feb 01 13:53:26 2017 +0000
Revision:
1:18e0f8aef32f
Parent:
0:5307f49cd305
Child:
2:e27fd3b65155
Version without debug

Who changed what in which revision?

UserRevisionLine numberNew contents of line
WilliamMarshQMUL 0:5307f49cd305 1 // Lab 3 Example Program 2
WilliamMarshQMUL 0:5307f49cd305 2 // -----------------------
WilliamMarshQMUL 0:5307f49cd305 3 // Periodically write to the AnalogOut to create a sine wave
WilliamMarshQMUL 0:5307f49cd305 4 // Alternate between two fixed frequencies every 5 sec
WilliamMarshQMUL 0:5307f49cd305 5 //
WilliamMarshQMUL 1:18e0f8aef32f 6 // THIS VERSION HAS NO DEBUGGING CODE
WilliamMarshQMUL 0:5307f49cd305 7
WilliamMarshQMUL 0:5307f49cd305 8 #include "mbed.h"
WilliamMarshQMUL 0:5307f49cd305 9 #include "rtos.h"
WilliamMarshQMUL 0:5307f49cd305 10 #include "sineTable.h"
WilliamMarshQMUL 0:5307f49cd305 11
WilliamMarshQMUL 0:5307f49cd305 12 Ticker tick ; // Creates periodic interrupt
WilliamMarshQMUL 0:5307f49cd305 13 AnalogOut ao(PTE30) ; // Analog output
WilliamMarshQMUL 0:5307f49cd305 14
WilliamMarshQMUL 1:18e0f8aef32f 15 // Function called periodically
WilliamMarshQMUL 1:18e0f8aef32f 16 // Write new value to AnalogOut
WilliamMarshQMUL 0:5307f49cd305 17 volatile int index = 0 ; // this variable is not just for debugging!!
WilliamMarshQMUL 0:5307f49cd305 18 void writeAout() {
WilliamMarshQMUL 0:5307f49cd305 19 ao.write_u16(sine[index]) ;
WilliamMarshQMUL 0:5307f49cd305 20 index = (index + 1) % 64 ;
WilliamMarshQMUL 0:5307f49cd305 21 }
WilliamMarshQMUL 0:5307f49cd305 22
WilliamMarshQMUL 0:5307f49cd305 23 // Control the frequency of updates
WilliamMarshQMUL 0:5307f49cd305 24 // Alternative between two frequencies
WilliamMarshQMUL 0:5307f49cd305 25 int main() {
WilliamMarshQMUL 1:18e0f8aef32f 26 int update_us = 1000 ; // 1ms
WilliamMarshQMUL 0:5307f49cd305 27 while (true) {
WilliamMarshQMUL 0:5307f49cd305 28 tick.attach_us(callback(&writeAout), update_us); // setup ticker to write to AnalogOut
WilliamMarshQMUL 0:5307f49cd305 29 Thread::wait(30000) ; // wait 30 sec - 30000ms
WilliamMarshQMUL 1:18e0f8aef32f 30 update_us = 2000 ; // 2ms
WilliamMarshQMUL 0:5307f49cd305 31 tick.attach_us(callback(&writeAout), update_us); // setup ticker to write to AnalogOut
WilliamMarshQMUL 0:5307f49cd305 32 Thread::wait(30000) ; // wait 30 sec - 30000ms
WilliamMarshQMUL 1:18e0f8aef32f 33 update_us = 1000 ; // 1ms
WilliamMarshQMUL 0:5307f49cd305 34 }
WilliamMarshQMUL 0:5307f49cd305 35 }