108 lines
5.2 KiB
Markdown
108 lines
5.2 KiB
Markdown
|
# IIR Filter Example
|
||
|
|
|
||
|
|
(See the README.md file in the upper level 'examples' directory for more information about examples.)
|
||
|
|
|
||
|
|
This example demonstrates how to use IIR filters functionality from esp-dsp library. Example does the following steps:
|
||
|
|
|
||
|
|
1. Initialize the library
|
||
|
|
2. Initialize input signal
|
||
|
|
3. Show LPF filter with Q factor 1
|
||
|
|
* Calculate iir filter coefficients
|
||
|
|
* Filter the input test signal (delta function)
|
||
|
|
* Shows impulse response on the plot
|
||
|
|
* Shows frequency response on the plot
|
||
|
|
* Calculate execution performance
|
||
|
|
4. The same for LPF filter with Q factor 10
|
||
|
|
|
||
|
|
## How to use 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 an typical example console output.
|
||
|
|
|
||
|
|
```
|
||
|
|
I (58) main: Start Example.
|
||
|
|
I (58) main: Impulse response of IIR filter with F=0.100000, qFactor=1.000000
|
||
|
|
I (68) view: Data min[8] = -0.060052, Data max[2] = 0.333517
|
||
|
|
________________________________________________________________
|
||
|
|
0 |
|
||
|
|
1 |
|
||
|
|
2 - |
|
||
|
|
3- - |
|
||
|
|
4 -------------------------------------------------------------|
|
||
|
|
5 |
|
||
|
|
6 |
|
||
|
|
7 |
|
||
|
|
8 |
|
||
|
|
9 |
|
||
|
|
0123456789012345678901234567890123456789012345678901234567890123
|
||
|
|
I (138) view: Plot: Length=128, min=-1.000000, max=1.000000
|
||
|
|
I (148) view: Data min[511] = -149.983795, Data max[0] = 0.000000
|
||
|
|
________________________________________________________________
|
||
|
|
0 |
|
||
|
|
1 |
|
||
|
|
2----------------- |
|
||
|
|
3 ---------- |
|
||
|
|
4 ------------- |
|
||
|
|
5 ---------- |
|
||
|
|
6 ------- |
|
||
|
|
7 --- |
|
||
|
|
8 -- |
|
||
|
|
9 --|
|
||
|
|
0123456789012345678901234567890123456789012345678901234567890123
|
||
|
|
I (228) view: Plot: Length=512, min=-100.000000, max=0.000000
|
||
|
|
I (228) main: IIR for 1024 samples take 20276 cycles
|
||
|
|
I (238) main: Impulse response of IIR filter with F=0.100000, qFactor=10.000000
|
||
|
|
I (248) view: Data min[7] = -0.453739, Data max[2] = 0.526114
|
||
|
|
________________________________________________________________
|
||
|
|
0 |
|
||
|
|
1 |
|
||
|
|
2 - - |
|
||
|
|
3- - - - --- --- - - |
|
||
|
|
4- - - - - ---- -------------------------------------|
|
||
|
|
5 -- -- -- -- |
|
||
|
|
6 |
|
||
|
|
7 |
|
||
|
|
8 |
|
||
|
|
9 |
|
||
|
|
0123456789012345678901234567890123456789012345678901234567890123
|
||
|
|
I (318) view: Plot: Length=128, min=-1.000000, max=1.000000
|
||
|
|
I (328) view: Data min[511] = -149.480377, Data max[0] = 0.000000
|
||
|
|
________________________________________________________________
|
||
|
|
0 -- |
|
||
|
|
1 -- - |
|
||
|
|
2---------- ----- |
|
||
|
|
3 -------- |
|
||
|
|
4 ------------ |
|
||
|
|
5 ---------- |
|
||
|
|
6 ------- |
|
||
|
|
7 --- |
|
||
|
|
8 -- |
|
||
|
|
9 --|
|
||
|
|
0123456789012345678901234567890123456789012345678901234567890123
|
||
|
|
I (408) view: Plot: Length=512, min=-100.000000, max=0.000000
|
||
|
|
I (408) main: IIR for 1024 samples take 17456 cycles
|
||
|
|
I (418) main: End Example.
|
||
|
|
|
||
|
|
```
|