espvban/ESPIDFNEW/managed_components/espressif__esp-dsp/examples/fir

FIR Filter Example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

This example demonstrates how to use FIR filter functionality from esp-dsp library. Example does the following steps:

1. Initialize the FFT library
2. Initialize input signal
   • 1st Sine wave (f = 0.2Fs)
   • 2nd Sine wave (f = 0.4Fs)
   • Combine the waves
3. Show input signal
   • Calculate windows coefficients
   • Apply the windowing to the input signal
   • Do the FFT
   • Show the frequency response on a plot
   • Calculate execution performance
4. Show filtered signal
   • Initialize the FIR filter library
   • Calculate Windowed-Sinc coefficients of FIR filter
   • Apply the FIR filter to the input signal
   • Do the FFT
   • Show the frequency response on a plot
   • Calculate execution performance

How to use the example

Hardware required

This example does not require any special hardware, and can be run on any common development board.

Configure the project

Under Component Config ---> DSP Library ---> DSP Optimization, it's possible to choose either the optimized or ANSI implementation, to compare them.

Build and flash

Build the project and flash it to the board, then run monitor tool to view serial output (replace PORT with serial port name):

idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example output

Here is a typical example of console output.

I (340) main: Start Example.
I (400) view: Data min[388] = -108.419342, Data max[205] = 30.267143
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 0123456789012345678901234567890123456789012345678901234567890123
I (470) view: Plot: Length=512, min=-120.000000, max=40.000000


I (490) view: Data min[254] = -114.853371, Data max[205] = 27.247583
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 0123456789012345678901234567890123456789012345678901234567890123
I (560) view: Plot: Length=256, min=-120.000000, max=40.000000
I (560) main: FIR for 1024 samples and decimation 2 takes 763647 cycles
I (570) main: End Example.