Charles Tritt / Mbed 2 deprecated AnalogSine

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Dependencies:   mbed

main.cpp@0:076821894a5d, 2017-10-26 (annotated)

Committer:
CSTritt
Date:
Thu Oct 26 19:25:24 2017 +0000
Revision:
0:076821894a5d
Initial version.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
CSTritt 0:076821894a5d 1 /*
CSTritt 0:076821894a5d 2 Project: AnalogSine (based on Nucleo_sinwave_output example)
CSTritt 0:076821894a5d 3 File: main.cpp
CSTritt 0:076821894a5d 4 Modified by by: Dr. C. S. Tritt
CSTritt 0:076821894a5d 5 Last revision on: 9/26/17 (v. 1.0)
CSTritt 0:076821894a5d 6
CSTritt 0:076821894a5d 7 Generates sine and cosine wave forms to demonstrate D to A operation. Use a
CSTritt 0:076821894a5d 8 data buffer for maximum speed (not necessary for 4 mS samples & 1.0 Hz
CSTritt 0:076821894a5d 9 signal). Output clips at a bit 0 and 3.3 V, so use AMPLITUDE <= 0.4 and
CSTritt 0:076821894a5d 10 OFFSET = 1.1. Zoom Horizontal scale out on MSOX2012A scopes and wait for
CSTritt 0:076821894a5d 11 refresh. Without wait, max. freq. (with both channels) is about 2 kHz.
CSTritt 0:076821894a5d 12 */
CSTritt 0:076821894a5d 13 #include "mbed.h"
CSTritt 0:076821894a5d 14
CSTritt 0:076821894a5d 15 #if !DEVICE_ANALOGOUT // Flag set by mbed.
CSTritt 0:076821894a5d 16 #error AnalogOut is not supported on this device. // Abort compilation.
CSTritt 0:076821894a5d 17 #else
CSTritt 0:076821894a5d 18 AnalogOut my_Sin(PA_4); // Sine
CSTritt 0:076821894a5d 19 AnalogOut my_Cos(PA_5); // Cosine
CSTritt 0:076821894a5d 20
CSTritt 0:076821894a5d 21 const float PI = 3.14159265f; // Value of Pi for radians calculation.
CSTritt 0:076821894a5d 22 const float AMPLITUDE = 0.4f; // x * 3.3V. D to A is limited to < 3.3 V.
CSTritt 0:076821894a5d 23 const float OFFSET = 1.1f; // Make signal all possitive.
CSTritt 0:076821894a5d 24
CSTritt 0:076821894a5d 25 // Configuration for sinewave output
CSTritt 0:076821894a5d 26 const int BUFFER_SIZE = 250; // Elements (i.e., points).
CSTritt 0:076821894a5d 27 float buffer[BUFFER_SIZE];
CSTritt 0:076821894a5d 28
CSTritt 0:076821894a5d 29 void calculate_sinewave(void); // Fills buffer.
CSTritt 0:076821894a5d 30
CSTritt 0:076821894a5d 31 int main()
CSTritt 0:076821894a5d 32 {
CSTritt 0:076821894a5d 33 printf("Sinewave example\n");
CSTritt 0:076821894a5d 34 calculate_sinewave();
CSTritt 0:076821894a5d 35 while(true) {
CSTritt 0:076821894a5d 36 // sinewave output
CSTritt 0:076821894a5d 37 for (int i = 0; i < BUFFER_SIZE; i++) {
CSTritt 0:076821894a5d 38 my_Sin.write(buffer[i]); // Output a point.
CSTritt 0:076821894a5d 39 // Generate Cosine by shifting sine by 1/4 cycle.
CSTritt 0:076821894a5d 40 my_Cos.write(buffer[(i + BUFFER_SIZE/4) % BUFFER_SIZE]);
CSTritt 0:076821894a5d 41 wait_ms(4); // Was wait_us(10); Remove for max. freq.
CSTritt 0:076821894a5d 42 }
CSTritt 0:076821894a5d 43 }
CSTritt 0:076821894a5d 44 }
CSTritt 0:076821894a5d 45
CSTritt 0:076821894a5d 46 void calculate_sinewave(void) // This function fills the buffer.
CSTritt 0:076821894a5d 47 {
CSTritt 0:076821894a5d 48 for (int i = 0; i < BUFFER_SIZE; i++) {
CSTritt 0:076821894a5d 49 // Calculate radians from 0 to 2*Pi.
CSTritt 0:076821894a5d 50 float rads = (2.0f * PI * (float) i / (float)BUFFER_SIZE);
CSTritt 0:076821894a5d 51 // Fill the buffer.
CSTritt 0:076821894a5d 52 buffer[i] = AMPLITUDE * (sin(rads) + OFFSET); // Sine of radians.
CSTritt 0:076821894a5d 53 }
CSTritt 0:076821894a5d 54 }
CSTritt 0:076821894a5d 55 #endif