Chris Taylor / SignalGenerator

Provides a simple way to generate complex square wave signals on any available pin. In addition the SignalGenerator can generate a carrier wave which is useful when generating IR signals to control electronic devices like a TV etc. The signal generation can be carried out either synchronously or asynchronously. In the case of synchronous signal generation all interrupts can optionally be disabled to improve timing accuracy.

SignalGenerator.cpp@1:4a1bcc41c473, 2014-09-12 (annotated)

Committer:
taylorza
Date:
Fri Sep 12 04:13:43 2014 +0000
Revision:
1:4a1bcc41c473
Parent:
0:b7c65c0d82d3
Child:
2:b2a449bd787f
Added author details in comments

Who changed what in which revision?

UserRevisionLine numberNew contents of line
taylorza 1:4a1bcc41c473 1 ///////////////////////////////////////////////////////////////////////////////
taylorza 1:4a1bcc41c473 2 // Signal Generator
taylorza 1:4a1bcc41c473 3 // Author: Chris Taylor (taylorza)
taylorza 0:b7c65c0d82d3 4 #include "mbed.h"
taylorza 0:b7c65c0d82d3 5 #include "SignalGenerator.h"
taylorza 0:b7c65c0d82d3 6
taylorza 0:b7c65c0d82d3 7 SignalGenerator::SignalGenerator(PinName pin) : _pin(pin)
taylorza 0:b7c65c0d82d3 8 {
taylorza 0:b7c65c0d82d3 9 _pin = 0;
taylorza 0:b7c65c0d82d3 10 }
taylorza 0:b7c65c0d82d3 11
taylorza 0:b7c65c0d82d3 12 void SignalGenerator::set(bool pinState)
taylorza 0:b7c65c0d82d3 13 {
taylorza 0:b7c65c0d82d3 14 _pin = pinState ? 1 : 0;
taylorza 0:b7c65c0d82d3 15 }
taylorza 0:b7c65c0d82d3 16
taylorza 1:4a1bcc41c473 17 void SignalGenerator::set(
taylorza 1:4a1bcc41c473 18 bool initialState,
taylorza 1:4a1bcc41c473 19 uint32_t timingBuffer[],
taylorza 1:4a1bcc41c473 20 uint16_t bufferCount,
taylorza 1:4a1bcc41c473 21 uint32_t lastStateHoldTime,
taylorza 1:4a1bcc41c473 22 int carrierFrequency)
taylorza 0:b7c65c0d82d3 23 {
taylorza 0:b7c65c0d82d3 24 uint32_t carrierHalfPeriod = 0;
taylorza 0:b7c65c0d82d3 25
taylorza 0:b7c65c0d82d3 26 if (carrierFrequency > 0)
taylorza 0:b7c65c0d82d3 27 {
taylorza 0:b7c65c0d82d3 28 carrierHalfPeriod = (uint32_t)(500000 / carrierFrequency);
taylorza 0:b7c65c0d82d3 29
taylorza 0:b7c65c0d82d3 30 bool state = initialState;
taylorza 0:b7c65c0d82d3 31 for(uint16_t i = 0; i < bufferCount; i++)
taylorza 0:b7c65c0d82d3 32 {
taylorza 0:b7c65c0d82d3 33 int c = (int)((double)timingBuffer[i] / carrierHalfPeriod);
taylorza 0:b7c65c0d82d3 34 if (!state)
taylorza 0:b7c65c0d82d3 35 {
taylorza 0:b7c65c0d82d3 36 wait_us(timingBuffer[i]);
taylorza 0:b7c65c0d82d3 37 }
taylorza 0:b7c65c0d82d3 38 else
taylorza 0:b7c65c0d82d3 39 {
taylorza 0:b7c65c0d82d3 40 for(int j = 0; j < c; j += 2)
taylorza 0:b7c65c0d82d3 41 {
taylorza 0:b7c65c0d82d3 42 _pin = 1;
taylorza 0:b7c65c0d82d3 43 wait_us(carrierHalfPeriod);
taylorza 0:b7c65c0d82d3 44 _pin = 0;
taylorza 0:b7c65c0d82d3 45 wait_us(carrierHalfPeriod);
taylorza 0:b7c65c0d82d3 46 }
taylorza 0:b7c65c0d82d3 47 }
taylorza 0:b7c65c0d82d3 48 state = !state;
taylorza 0:b7c65c0d82d3 49 }
taylorza 0:b7c65c0d82d3 50
taylorza 0:b7c65c0d82d3 51 if (lastStateHoldTime > 0)
taylorza 0:b7c65c0d82d3 52 {
taylorza 0:b7c65c0d82d3 53 int c = (int)((double)lastStateHoldTime / carrierHalfPeriod);
taylorza 0:b7c65c0d82d3 54 if (!state)
taylorza 0:b7c65c0d82d3 55 {
taylorza 0:b7c65c0d82d3 56 wait_us(lastStateHoldTime);
taylorza 0:b7c65c0d82d3 57 }
taylorza 0:b7c65c0d82d3 58 else
taylorza 0:b7c65c0d82d3 59 {
taylorza 0:b7c65c0d82d3 60 for(int j = 0; j < c; j += 2)
taylorza 0:b7c65c0d82d3 61 {
taylorza 0:b7c65c0d82d3 62 _pin = 1;
taylorza 0:b7c65c0d82d3 63 wait_us(carrierHalfPeriod);
taylorza 0:b7c65c0d82d3 64 _pin = 0;
taylorza 0:b7c65c0d82d3 65 wait_us(carrierHalfPeriod);
taylorza 0:b7c65c0d82d3 66 }
taylorza 0:b7c65c0d82d3 67 }
taylorza 0:b7c65c0d82d3 68 }
taylorza 0:b7c65c0d82d3 69 }
taylorza 0:b7c65c0d82d3 70 else
taylorza 0:b7c65c0d82d3 71 {
taylorza 0:b7c65c0d82d3 72 set(initialState);
taylorza 0:b7c65c0d82d3 73 for(uint16_t i = 0; i < bufferCount; ++i)
taylorza 0:b7c65c0d82d3 74 {
taylorza 0:b7c65c0d82d3 75 wait_us(timingBuffer[i]);
taylorza 0:b7c65c0d82d3 76 _pin = !_pin;
taylorza 0:b7c65c0d82d3 77 }
taylorza 0:b7c65c0d82d3 78
taylorza 0:b7c65c0d82d3 79 if (lastStateHoldTime > 0)
taylorza 0:b7c65c0d82d3 80 {
taylorza 0:b7c65c0d82d3 81 wait_us(lastStateHoldTime);
taylorza 0:b7c65c0d82d3 82 }
taylorza 0:b7c65c0d82d3 83 }
taylorza 1:4a1bcc41c473 84 }