William Marsh
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.
Diff: main.cpp
- Revision:
- 4:75ad475aff41
- Parent:
- 3:2bf79a3c3cbc
- Child:
- 5:5161dd5f273e
--- a/main.cpp Wed Jan 23 17:56:42 2019 +0000
+++ b/main.cpp Mon Feb 04 16:12:23 2019 +0000
@@ -2,6 +2,10 @@
// -----------------------
// Periodically write to the AnalogOut to create a sine wave
// Alternate between two fixed frequencies every 5 sec
+//
+// This code uses the Ticker API to create a periodic interrupt
+// Devices used in this way must not call locks; a variant of
+// the AnalogOut device w/o locking is created for this.
//
// Updated for mbed 5
@@ -10,8 +14,21 @@
#include "mbed.h"
#include "sineTable.h"
+// --------------------------
+// This declaration introduces a derived version of the mbed AnalogOut
+// class with the locking removed.
+// You do NOT NEED TO UNDERSTAND this
+class AnalogOut_unsafe : public AnalogOut {
+ public:
+ AnalogOut_unsafe (PinName pin) : AnalogOut (pin) {}
+ protected:
+ virtual void lock() {}
+ virtual void unlock() {}
+};
+// --------------------------
+
Ticker tick ; // Creates periodic interrupt
-AnalogOut ao(PTE30) ; // Analog output
+AnalogOut_unsafe ao(PTE30) ; // Analog output
// Function called periodically
// Write new value to AnalogOut