88 lines
3.5 KiB
Markdown
88 lines
3.5 KiB
Markdown
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# FIR Filter Example
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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This example demonstrates how to use FIR filter functionality from esp-dsp library. Example does the following steps:
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1. Initialize the FFT library
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2. Initialize input signal
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* 1st Sine wave (f = 0.2Fs)
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* 2nd Sine wave (f = 0.4Fs)
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* Combine the waves
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3. Show input signal
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* Calculate windows coefficients
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* Apply the windowing to the input signal
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* Do the FFT
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* Show the frequency response on a plot
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* Calculate execution performance
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4. Show filtered signal
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* Initialize the FIR filter library
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* Calculate Windowed-Sinc coefficients of FIR filter
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* Apply the FIR filter to the input signal
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* Do the FFT
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* Show the frequency response on a plot
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* Calculate execution performance
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## How to use the example
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### Hardware required
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This example does not require any special hardware, and can be run on any common development board.
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### Configure the project
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Under Component Config ---> DSP Library ---> DSP Optimization, it's possible to choose either the optimized or ANSI implementation, to compare them.
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### Build and flash
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Build the project and flash it to the board, then run monitor tool to view serial output (replace PORT with serial port name):
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```
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idf.py -p PORT flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example output
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Here is a typical example of console output.
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```
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I (340) main: Start Example.
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I (400) view: Data min[388] = -108.419342, Data max[205] = 30.267143
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0123456789012345678901234567890123456789012345678901234567890123
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I (470) view: Plot: Length=512, min=-120.000000, max=40.000000
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I (490) view: Data min[254] = -114.853371, Data max[205] = 27.247583
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________________________________________________________________
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0123456789012345678901234567890123456789012345678901234567890123
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I (560) view: Plot: Length=256, min=-120.000000, max=40.000000
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I (560) main: FIR for 1024 samples and decimation 2 takes 763647 cycles
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I (570) main: End Example.
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```
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