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Cutoff frequency variable LPF, HPF, BPF, and BRF by FIR 160th-order filter.
Dependencies: UIT_ACM1602NI UITDSP_ADDA mbed UIT_AQM1602
main.cpp@1:58271fae2e01, 2014-12-09 (annotated)
- Committer:
- MikamiUitOpen
- Date:
- Tue Dec 09 06:04:35 2014 +0000
- Revision:
- 1:58271fae2e01
- Parent:
- 0:ca94cfc90365
- Child:
- 3:24b6aa1a19ba
2
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
MikamiUitOpen | 0:ca94cfc90365 | 1 | //------------------------------------------------------------------------------ |
MikamiUitOpen | 1:58271fae2e01 | 2 | // Cutoff frequency variable LPF, HPF, BPF and BRF by FIR 160th-order filter |
MikamiUitOpen | 0:ca94cfc90365 | 3 | // A0: Signal to be filtered |
MikamiUitOpen | 0:ca94cfc90365 | 4 | // A2: Value which controls cutoff frequency |
MikamiUitOpen | 0:ca94cfc90365 | 5 | // |
MikamiUitOpen | 0:ca94cfc90365 | 6 | // 1: LPF, 3: HPF, 5: BPF, 7: BRF, even: through |
MikamiUitOpen | 1:58271fae2e01 | 7 | // 2014/12/09, Copyright (c) 2014 MIKAMI, Naoki |
MikamiUitOpen | 0:ca94cfc90365 | 8 | //------------------------------------------------------------------------------ |
MikamiUitOpen | 0:ca94cfc90365 | 9 | |
MikamiUitOpen | 0:ca94cfc90365 | 10 | #include "mbed.h" |
MikamiUitOpen | 0:ca94cfc90365 | 11 | |
MikamiUitOpen | 0:ca94cfc90365 | 12 | #include "ADC_Interrupt.hpp" // for ADC using interrupt |
MikamiUitOpen | 0:ca94cfc90365 | 13 | #include "DAC_MCP4922.hpp" // for DAC MCP4922 |
MikamiUitOpen | 0:ca94cfc90365 | 14 | #include "ACM1602NI.hpp" // for LCD display |
MikamiUitOpen | 0:ca94cfc90365 | 15 | |
MikamiUitOpen | 0:ca94cfc90365 | 16 | #include "WindowingDesign.hpp" // for design of FIR filter |
MikamiUitOpen | 0:ca94cfc90365 | 17 | |
MikamiUitOpen | 0:ca94cfc90365 | 18 | using namespace Mikami; |
MikamiUitOpen | 0:ca94cfc90365 | 19 | |
MikamiUitOpen | 0:ca94cfc90365 | 20 | const int FS_ = 16000; // Sampling frequency: 16 kHz |
MikamiUitOpen | 0:ca94cfc90365 | 21 | ADC_Intr myAdc_(A0, FS_, A1, A2); |
MikamiUitOpen | 0:ca94cfc90365 | 22 | DAC_MCP4922 myDac_; |
MikamiUitOpen | 0:ca94cfc90365 | 23 | |
MikamiUitOpen | 0:ca94cfc90365 | 24 | const int ORDER_ = 160; |
MikamiUitOpen | 0:ca94cfc90365 | 25 | float hm_[ORDER_/2+1]; |
MikamiUitOpen | 0:ca94cfc90365 | 26 | float xn_[ORDER_+1]; |
MikamiUitOpen | 0:ca94cfc90365 | 27 | |
MikamiUitOpen | 0:ca94cfc90365 | 28 | DigitalIn sw1_(D2, PullDown); |
MikamiUitOpen | 0:ca94cfc90365 | 29 | DigitalIn sw2_(D3, PullDown); |
MikamiUitOpen | 0:ca94cfc90365 | 30 | DigitalIn sw4_(D4, PullDown); |
MikamiUitOpen | 0:ca94cfc90365 | 31 | DigitalIn sw8_(D5, PullDown); |
MikamiUitOpen | 0:ca94cfc90365 | 32 | |
MikamiUitOpen | 0:ca94cfc90365 | 33 | WindowingDesign design_(ORDER_, FS_); |
MikamiUitOpen | 0:ca94cfc90365 | 34 | |
MikamiUitOpen | 0:ca94cfc90365 | 35 | uint16_t a2_ = 0; // Inputted data from A2 pin |
MikamiUitOpen | 0:ca94cfc90365 | 36 | |
MikamiUitOpen | 0:ca94cfc90365 | 37 | // Interrupt service routine for ADC |
MikamiUitOpen | 0:ca94cfc90365 | 38 | void AdcIsr() |
MikamiUitOpen | 0:ca94cfc90365 | 39 | { |
MikamiUitOpen | 1:58271fae2e01 | 40 | xn_[0] = myAdc_.Read(); // Read from A0 |
MikamiUitOpen | 0:ca94cfc90365 | 41 | |
MikamiUitOpen | 0:ca94cfc90365 | 42 | myAdc_.Select3rdChannel(); // Select A2 |
MikamiUitOpen | 0:ca94cfc90365 | 43 | myAdc_.SoftStart(); // ADC start for A2 input |
MikamiUitOpen | 0:ca94cfc90365 | 44 | |
MikamiUitOpen | 0:ca94cfc90365 | 45 | //----------------------------------------- |
MikamiUitOpen | 0:ca94cfc90365 | 46 | // Execute FIR filter |
MikamiUitOpen | 0:ca94cfc90365 | 47 | float yn = hm_[ORDER_/2]*xn_[ORDER_/2]; |
MikamiUitOpen | 0:ca94cfc90365 | 48 | for (int k=0; k<ORDER_/2; k++) |
MikamiUitOpen | 0:ca94cfc90365 | 49 | yn = yn + hm_[k]*(xn_[k] + xn_[ORDER_-k]); |
MikamiUitOpen | 0:ca94cfc90365 | 50 | |
MikamiUitOpen | 0:ca94cfc90365 | 51 | for (int k=ORDER_; k>0; k--) |
MikamiUitOpen | 0:ca94cfc90365 | 52 | xn_[k] = xn_[k-1]; // move input signals |
MikamiUitOpen | 0:ca94cfc90365 | 53 | //----------------------------------------- |
MikamiUitOpen | 0:ca94cfc90365 | 54 | |
MikamiUitOpen | 0:ca94cfc90365 | 55 | if (sw1_ == 0) myDac_.Write(xn_[0]); // Using no filter |
MikamiUitOpen | 0:ca94cfc90365 | 56 | else myDac_.Write(yn); // Using filter |
MikamiUitOpen | 0:ca94cfc90365 | 57 | |
MikamiUitOpen | 0:ca94cfc90365 | 58 | // Read value which controls cutoff frequency |
MikamiUitOpen | 0:ca94cfc90365 | 59 | a2_ = myAdc_.ReadWait_u16(); |
MikamiUitOpen | 0:ca94cfc90365 | 60 | |
MikamiUitOpen | 0:ca94cfc90365 | 61 | myAdc_.Select1stChannel(); // Select A0 |
MikamiUitOpen | 0:ca94cfc90365 | 62 | myAdc_.ClearPending_EnableIRQ();// Clear pending interrupt |
MikamiUitOpen | 0:ca94cfc90365 | 63 | // and enable ADC_IRQn |
MikamiUitOpen | 0:ca94cfc90365 | 64 | } |
MikamiUitOpen | 0:ca94cfc90365 | 65 | |
MikamiUitOpen | 0:ca94cfc90365 | 66 | int main() |
MikamiUitOpen | 0:ca94cfc90365 | 67 | { |
MikamiUitOpen | 0:ca94cfc90365 | 68 | myDac_.ScfClockTim3(670000); // cutoff frequency: 6.7 kHz |
MikamiUitOpen | 0:ca94cfc90365 | 69 | |
MikamiUitOpen | 0:ca94cfc90365 | 70 | Acm1602Ni lcd; // objetc for display using LCD |
MikamiUitOpen | 0:ca94cfc90365 | 71 | |
MikamiUitOpen | 0:ca94cfc90365 | 72 | // Clear buffer in FIR filter |
MikamiUitOpen | 0:ca94cfc90365 | 73 | for (int n=0; n<=ORDER_; n++) |
MikamiUitOpen | 0:ca94cfc90365 | 74 | xn_[n] = 0; |
MikamiUitOpen | 0:ca94cfc90365 | 75 | myAdc_.SetIntrVec(AdcIsr); // Assign ISR for ADC interrupt |
MikamiUitOpen | 0:ca94cfc90365 | 76 | |
MikamiUitOpen | 0:ca94cfc90365 | 77 | float fc1 = 0; |
MikamiUitOpen | 0:ca94cfc90365 | 78 | while (true) |
MikamiUitOpen | 0:ca94cfc90365 | 79 | { |
MikamiUitOpen | 0:ca94cfc90365 | 80 | int sw = (sw8_ << 3) | (sw4_ << 2) | (sw2_ << 1) | sw1_; |
MikamiUitOpen | 0:ca94cfc90365 | 81 | if (sw1_ == 0) |
MikamiUitOpen | 0:ca94cfc90365 | 82 | { |
MikamiUitOpen | 0:ca94cfc90365 | 83 | printf("Through\r\n"); |
MikamiUitOpen | 0:ca94cfc90365 | 84 | lcd.ClearLine(1); |
MikamiUitOpen | 0:ca94cfc90365 | 85 | lcd.WriteStringXY("Through ", 0, 0); |
MikamiUitOpen | 0:ca94cfc90365 | 86 | wait(0.2f); |
MikamiUitOpen | 0:ca94cfc90365 | 87 | lcd.ClearLine(0); |
MikamiUitOpen | 0:ca94cfc90365 | 88 | fc1 = 0; |
MikamiUitOpen | 0:ca94cfc90365 | 89 | } |
MikamiUitOpen | 0:ca94cfc90365 | 90 | else |
MikamiUitOpen | 0:ca94cfc90365 | 91 | { |
MikamiUitOpen | 1:58271fae2e01 | 92 | // fc: cutoff or center frequency, 200 -- 2000 Hz |
MikamiUitOpen | 1:58271fae2e01 | 93 | float fc = 1800.0f*(a2_/4095.6f) + 200.0f; |
MikamiUitOpen | 1:58271fae2e01 | 94 | |
MikamiUitOpen | 0:ca94cfc90365 | 95 | if (fabs(fc - fc1) > 10.0f) |
MikamiUitOpen | 0:ca94cfc90365 | 96 | { |
MikamiUitOpen | 0:ca94cfc90365 | 97 | printf("fc = %4d\r\n", int(fc+0.5f)); |
MikamiUitOpen | 0:ca94cfc90365 | 98 | char str[18]; |
MikamiUitOpen | 0:ca94cfc90365 | 99 | sprintf(str, "fc = %4d Hz", int(fc+0.5f)); |
MikamiUitOpen | 0:ca94cfc90365 | 100 | lcd.WriteStringXY(str, 0, 1); |
MikamiUitOpen | 1:58271fae2e01 | 101 | fc1 = fc; |
MikamiUitOpen | 0:ca94cfc90365 | 102 | |
MikamiUitOpen | 1:58271fae2e01 | 103 | switch (sw) |
MikamiUitOpen | 0:ca94cfc90365 | 104 | { |
MikamiUitOpen | 1:58271fae2e01 | 105 | case 1: printf("LPF\r\n"); |
MikamiUitOpen | 1:58271fae2e01 | 106 | lcd.WriteStringXY("LPF", 0, 0); |
MikamiUitOpen | 1:58271fae2e01 | 107 | design_.Design(ORDER_, design_.LPF, fc, 0, hm_); |
MikamiUitOpen | 1:58271fae2e01 | 108 | break; |
MikamiUitOpen | 1:58271fae2e01 | 109 | case 3: printf("HPF\r\n"); |
MikamiUitOpen | 1:58271fae2e01 | 110 | lcd.WriteStringXY("HPF", 0, 0); |
MikamiUitOpen | 1:58271fae2e01 | 111 | design_.Design(ORDER_, design_.HPF, fc, 0, hm_); |
MikamiUitOpen | 1:58271fae2e01 | 112 | break; |
MikamiUitOpen | 1:58271fae2e01 | 113 | case 5: printf("BPF\r\n"); |
MikamiUitOpen | 1:58271fae2e01 | 114 | lcd.WriteStringXY("BPF", 0, 0); |
MikamiUitOpen | 1:58271fae2e01 | 115 | design_.Design(ORDER_, design_.BPF, fc-100, fc+100, hm_); |
MikamiUitOpen | 1:58271fae2e01 | 116 | break; |
MikamiUitOpen | 1:58271fae2e01 | 117 | case 7: printf("BRF\r\n"); |
MikamiUitOpen | 1:58271fae2e01 | 118 | lcd.WriteStringXY("BRF", 0, 0); |
MikamiUitOpen | 1:58271fae2e01 | 119 | design_.Design(ORDER_, design_.BRF, fc-100, fc+100, hm_); |
MikamiUitOpen | 1:58271fae2e01 | 120 | break; |
MikamiUitOpen | 0:ca94cfc90365 | 121 | } |
MikamiUitOpen | 0:ca94cfc90365 | 122 | } |
MikamiUitOpen | 0:ca94cfc90365 | 123 | } |
MikamiUitOpen | 0:ca94cfc90365 | 124 | wait(0.1f); |
MikamiUitOpen | 0:ca94cfc90365 | 125 | } |
MikamiUitOpen | 0:ca94cfc90365 | 126 | } |