Bob Merrison-Hort / Mbed 2 deprecated elec350

elec350

Dependencies:   mbed

Fork of elec350 by Bob Merrison-Hort

microphone.cpp@16:721e41936a07, 2015-11-19 (annotated)

Committer:
rmerrisonhort
Date:
Thu Nov 19 10:06:45 2015 +0000
Revision:
16:721e41936a07
Parent:
14:b1f94dd4a47f 
Added InternalTemperature class.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rmerrisonhort 9:3801e1da153b 1 #include "microphone.h"
rmerrisonhort 9:3801e1da153b 2
rmerrisonhort 9:3801e1da153b 3 bool _mic_toggle = false;
rmerrisonhort 9:3801e1da153b 4 uint8_t _mic_pulses= 0;
rmerrisonhort 9:3801e1da153b 5 uint8_t _mic_pulses_buffered = 0;
rmerrisonhort 9:3801e1da153b 6 uint8_t _mic_counter = 0;
rmerrisonhort 9:3801e1da153b 7 DigitalIn* _mic_d;
rmerrisonhort 9:3801e1da153b 8 DigitalOut* _mic_clk;
rmerrisonhort 9:3801e1da153b 9
rmerrisonhort 9:3801e1da153b 10 void _mic_timer_int()
rmerrisonhort 9:3801e1da153b 11 {
rmerrisonhort 9:3801e1da153b 12 // If clock output to mic is low, read data pin and increment
rmerrisonhort 9:3801e1da153b 13 // pulse count if it's high.
rmerrisonhort 9:3801e1da153b 14 if (!_mic_toggle) {
rmerrisonhort 9:3801e1da153b 15 _mic_counter += 1;
rmerrisonhort 9:3801e1da153b 16 if (_mic_counter == 0) {
rmerrisonhort 9:3801e1da153b 17 _mic_pulses_buffered = _mic_pulses;
rmerrisonhort 9:3801e1da153b 18 _mic_pulses = 0;
rmerrisonhort 9:3801e1da153b 19 }
rmerrisonhort 9:3801e1da153b 20 if (_mic_d->read()) _mic_pulses++;
rmerrisonhort 9:3801e1da153b 21 }
rmerrisonhort 9:3801e1da153b 22
rmerrisonhort 9:3801e1da153b 23 // Toggle clock output to mic
rmerrisonhort 9:3801e1da153b 24 _mic_toggle = !_mic_toggle;
rmerrisonhort 9:3801e1da153b 25 _mic_clk->write(_mic_toggle);
rmerrisonhort 9:3801e1da153b 26
rmerrisonhort 9:3801e1da153b 27 // Clear interrupt
rmerrisonhort 9:3801e1da153b 28 TIM3->SR &= ~TIM_SR_UIF;
rmerrisonhort 9:3801e1da153b 29 }
rmerrisonhort 9:3801e1da153b 30
rmerrisonhort 9:3801e1da153b 31 Microphone::Microphone()
rmerrisonhort 9:3801e1da153b 32 {
rmerrisonhort 9:3801e1da153b 33 this->isStarted = false;
rmerrisonhort 9:3801e1da153b 34 }
rmerrisonhort 9:3801e1da153b 35
rmerrisonhort 9:3801e1da153b 36 void Microphone::start()
rmerrisonhort 9:3801e1da153b 37 {
rmerrisonhort 14:b1f94dd4a47f 38 if (!this->isStarted) {
rmerrisonhort 9:3801e1da153b 39 // Two pins: clock to microphone and data from microphone.
rmerrisonhort 9:3801e1da153b 40 _mic_d = new DigitalIn(PC_3);
rmerrisonhort 9:3801e1da153b 41 _mic_clk = new DigitalOut(PB_10);
rmerrisonhort 9:3801e1da153b 42
rmerrisonhort 9:3801e1da153b 43 // Use timer 3 to sample from the MP45DT02 microphone.
rmerrisonhort 9:3801e1da153b 44
rmerrisonhort 9:3801e1da153b 45 // Enable timer.
rmerrisonhort 9:3801e1da153b 46 RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
rmerrisonhort 9:3801e1da153b 47
rmerrisonhort 9:3801e1da153b 48 // Scale timer so ticks are 100ns
rmerrisonhort 9:3801e1da153b 49 uint32_t PCLK = SystemCoreClock / 4;
rmerrisonhort 9:3801e1da153b 50 uint32_t prescale = PCLK / 10000000; // 10Mhz (100ns ticks)
rmerrisonhort 9:3801e1da153b 51 TIM3->PSC = prescale - 1;
rmerrisonhort 9:3801e1da153b 52
rmerrisonhort 9:3801e1da153b 53 // Enable counter
rmerrisonhort 9:3801e1da153b 54 TIM3->CR1 |= TIM_CR1_CEN;
rmerrisonhort 9:3801e1da153b 55
rmerrisonhort 9:3801e1da153b 56 // Set auto-reset after five ticks (500ns).
rmerrisonhort 9:3801e1da153b 57 TIM3->ARR = 4;
rmerrisonhort 9:3801e1da153b 58
rmerrisonhort 9:3801e1da153b 59 // Re-initialize counter.
rmerrisonhort 9:3801e1da153b 60 TIM3->EGR |= TIM_EGR_UG;
rmerrisonhort 9:3801e1da153b 61
rmerrisonhort 9:3801e1da153b 62 // Set up and enable interrupt for when timer overflows.
rmerrisonhort 9:3801e1da153b 63 NVIC_SetVector(TIM3_IRQn, (uint32_t)_mic_timer_int);
rmerrisonhort 9:3801e1da153b 64 NVIC_EnableIRQ(TIM3_IRQn);
rmerrisonhort 9:3801e1da153b 65 TIM3->DIER |= TIM_DIER_UIE;
rmerrisonhort 14:b1f94dd4a47f 66 this->isStarted = true;
rmerrisonhort 9:3801e1da153b 67 }
rmerrisonhort 9:3801e1da153b 68 }
rmerrisonhort 9:3801e1da153b 69
rmerrisonhort 9:3801e1da153b 70 void Microphone::stop() // Not tested!
rmerrisonhort 9:3801e1da153b 71 {
rmerrisonhort 14:b1f94dd4a47f 72 if (this->isStarted) {
rmerrisonhort 14:b1f94dd4a47f 73 // Disable interrupts.
rmerrisonhort 14:b1f94dd4a47f 74 NVIC_SetVector(TIM3_IRQn, (uint32_t)_mic_timer_int);
rmerrisonhort 14:b1f94dd4a47f 75 NVIC_DisableIRQ(TIM3_IRQn);
rmerrisonhort 14:b1f94dd4a47f 76 TIM3->DIER &= ~TIM_DIER_UIE;
rmerrisonhort 14:b1f94dd4a47f 77
rmerrisonhort 14:b1f94dd4a47f 78 // Disable counter
rmerrisonhort 14:b1f94dd4a47f 79 TIM3->CR1 &= ~TIM_CR1_CEN;
rmerrisonhort 14:b1f94dd4a47f 80
rmerrisonhort 14:b1f94dd4a47f 81 // Disable timer.
rmerrisonhort 14:b1f94dd4a47f 82 RCC->APB1ENR &= ~RCC_APB1ENR_TIM3EN;
rmerrisonhort 14:b1f94dd4a47f 83
rmerrisonhort 14:b1f94dd4a47f 84 // Clear interrupt
rmerrisonhort 14:b1f94dd4a47f 85 TIM3->SR &= ~TIM_SR_UIF;
rmerrisonhort 9:3801e1da153b 86
rmerrisonhort 14:b1f94dd4a47f 87 delete _mic_d; _mic_d = NULL;
rmerrisonhort 14:b1f94dd4a47f 88 delete _mic_clk; _mic_clk = NULL;
rmerrisonhort 14:b1f94dd4a47f 89 }
rmerrisonhort 9:3801e1da153b 90 }
rmerrisonhort 9:3801e1da153b 91
rmerrisonhort 9:3801e1da153b 92 int8_t Microphone::read()
rmerrisonhort 9:3801e1da153b 93 {
rmerrisonhort 14:b1f94dd4a47f 94 if (this->isStarted) {
rmerrisonhort 14:b1f94dd4a47f 95 return (int8_t)((uint16_t)_mic_pulses_buffered - 128);
rmerrisonhort 14:b1f94dd4a47f 96 } else {
rmerrisonhort 14:b1f94dd4a47f 97 return 0;
rmerrisonhort 14:b1f94dd4a47f 98 }
rmerrisonhort 12:ae626e46b996 99 }