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@5:5161dd5f273e, 2020-02-06 (annotated)

Committer:
WilliamMarshQMUL
Date:
Thu Feb 06 09:03:54 2020 +0000
Revision:
5:5161dd5f273e
Parent:
4:75ad475aff41 
Update mbed. Repace wait with sleep for

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 4:75ad475aff41 5 //
WilliamMarshQMUL 4:75ad475aff41 6 // This code uses the Ticker API to create a periodic interrupt
WilliamMarshQMUL 4:75ad475aff41 7 // Devices used in this way must not call locks; a variant of
WilliamMarshQMUL 4:75ad475aff41 8 // the AnalogOut device w/o locking is created for this.
WilliamMarshQMUL 0:5307f49cd305 9 //
WilliamMarshQMUL 2:e27fd3b65155 10 // Updated for mbed 5
WilliamMarshQMUL 2:e27fd3b65155 11
WilliamMarshQMUL 1:18e0f8aef32f 12 // THIS VERSION HAS NO DEBUGGING CODE
WilliamMarshQMUL 0:5307f49cd305 13
WilliamMarshQMUL 0:5307f49cd305 14 #include "mbed.h"
WilliamMarshQMUL 0:5307f49cd305 15 #include "sineTable.h"
WilliamMarshQMUL 0:5307f49cd305 16
WilliamMarshQMUL 4:75ad475aff41 17 // --------------------------
WilliamMarshQMUL 4:75ad475aff41 18 // This declaration introduces a derived version of the mbed AnalogOut
WilliamMarshQMUL 4:75ad475aff41 19 // class with the locking removed.
WilliamMarshQMUL 4:75ad475aff41 20 // You do NOT NEED TO UNDERSTAND this
WilliamMarshQMUL 4:75ad475aff41 21 class AnalogOut_unsafe : public AnalogOut {
WilliamMarshQMUL 4:75ad475aff41 22 public:
WilliamMarshQMUL 4:75ad475aff41 23 AnalogOut_unsafe (PinName pin) : AnalogOut (pin) {}
WilliamMarshQMUL 4:75ad475aff41 24 protected:
WilliamMarshQMUL 4:75ad475aff41 25 virtual void lock() {}
WilliamMarshQMUL 4:75ad475aff41 26 virtual void unlock() {}
WilliamMarshQMUL 4:75ad475aff41 27 };
WilliamMarshQMUL 4:75ad475aff41 28 // --------------------------
WilliamMarshQMUL 4:75ad475aff41 29
WilliamMarshQMUL 0:5307f49cd305 30 Ticker tick ; // Creates periodic interrupt
WilliamMarshQMUL 4:75ad475aff41 31 AnalogOut_unsafe ao(PTE30) ; // Analog output
WilliamMarshQMUL 0:5307f49cd305 32
WilliamMarshQMUL 1:18e0f8aef32f 33 // Function called periodically
WilliamMarshQMUL 1:18e0f8aef32f 34 // Write new value to AnalogOut
WilliamMarshQMUL 2:e27fd3b65155 35 volatile int index = 0 ; // index into array of sin values
WilliamMarshQMUL 0:5307f49cd305 36 void writeAout() {
WilliamMarshQMUL 0:5307f49cd305 37 ao.write_u16(sine[index]) ;
WilliamMarshQMUL 0:5307f49cd305 38 index = (index + 1) % 64 ;
WilliamMarshQMUL 0:5307f49cd305 39 }
WilliamMarshQMUL 0:5307f49cd305 40
WilliamMarshQMUL 0:5307f49cd305 41 // Control the frequency of updates
WilliamMarshQMUL 0:5307f49cd305 42 // Alternative between two frequencies
WilliamMarshQMUL 0:5307f49cd305 43 int main() {
WilliamMarshQMUL 1:18e0f8aef32f 44 int update_us = 1000 ; // 1ms
WilliamMarshQMUL 0:5307f49cd305 45 while (true) {
WilliamMarshQMUL 0:5307f49cd305 46 tick.attach_us(callback(&writeAout), update_us); // setup ticker to write to AnalogOut
WilliamMarshQMUL 5:5161dd5f273e 47 ThisThread::sleep_for(30000) ; // wait 30 sec
WilliamMarshQMUL 1:18e0f8aef32f 48 update_us = 2000 ; // 2ms
WilliamMarshQMUL 0:5307f49cd305 49 tick.attach_us(callback(&writeAout), update_us); // setup ticker to write to AnalogOut
WilliamMarshQMUL 5:5161dd5f273e 50 ThisThread::sleep_for(30000) ; // wait 30 sec
WilliamMarshQMUL 1:18e0f8aef32f 51 update_us = 1000 ; // 1ms
WilliamMarshQMUL 0:5307f49cd305 52 }
WilliamMarshQMUL 0:5307f49cd305 53 }