Datasheet

Development Systems Ordering Guide
DS30177T-page 22 © 2005 Microchip Technology Inc.
Digital Filter Design/Digital Filter Design Lite
The Digital Filter Design tool for the dsPIC
®
16-bit Digital
Signal Controllers makes designing, analyzing and
implementing Finite Impulse Response (FIR) and Infinite
Impulse Response (IIR) digital filters easy through a
menu-driven and intuitive user interface. The filter design
tool performs complex mathematical computations for
filter design, provides superior graphical displays and
generates comprehensive design reports. Desired filter
frequency specifications are entered and the tool
automatically generates the filter code and coefficient files
ready to use in the MPLAB
®
IDE. System analysis of the
filter transfer function is supported with multiple generated
graphs, such as: magnitude, phase, group delay, log
magnitude, impulse response and pole/zero locations.
Finite Impulse Response Filter Design
• Design method selection:
- FIR Windows design
- FIR Equiripple design (Parks-McClellan)
• Low-pass, high-pass, band-pass and band-stop filters
• FIR filters can have up to 513 taps
• Following window functions are supported:
- Rectangular: 4 Term Cosine
- Hanning (Hann): 4 Term Cosine with continuous 5th
derivative
- Hamming: Minimum 4 Term Cosine
- Triangular: Good 4 Term Blackman Harris
- Blackman: Harris Flat Top
- Exact Blackman: Kaiser
- 3 Term Cosine: Dolph-Tschebyscheff
- 3 Term Cosine with continuous 3rd derivative: Taylor
- Minimum 3 Term Cosine: Gaussian
• Reports show design details, such as window
coefficients and Impulse Response, prior to
multiplying by the window function
• Filters are designed for a maximum gain of 1
Comparison – Filter Design vs. Filter Design Lite
Infinite Impulse Response Filter Design
• Low-pass, high-pass, band-pass and band-stop filters
• Filter orders up to 10 for low-pass and high-pass filters
• Filter orders up to 20 for band-pass and band-stop filters
• Five analog prototype filters are available:
- Butterworth
- Tschebyscheff
- Inverse Tschebyscheff
- Elliptic
-Bessel
• Digital Transformations are performed by bilinear
transformation method
• Reports show design details, such as all
transformations from normalized low-pass filter to
desired filter
Code Generation Features
• Generated files are compliant with the Microchip
dsPIC30F C30 C Compiler, Assembler and Linker
• Choice of placement of coefficients in program space
or data space
• ‘C’ wrapper/header code generation
Graphs
• Magnitude Response vs. Frequency
• Log Magnitude vs. Frequency
• Phase Response vs. Frequency
• Group Delay vs. Frequency
• Impulse Response vs. Time (per sample)
• Step Response vs. Time (per sample)
• Pole and Zero Locations (IIR only)
Filter Design Filter Design Lite
Low-pass ✓✓
High-pass ✓✓
Band-pass ✓✓
Band-stop ✓
FIR Taps Up to 513 Up to 64
IIR Taps for LP, HP Up to 10 Up to 4
IIR Taps for BP, BS Up to 20 Up to 8
Generate ASM Code ✓ —
Export to MPLAB
®
IDE ✓✓
Export to MPLAB
®
C30 C Compiler ✓✓
MATLAB
®
Support ✓✓
Ordering Information:
SW300001 Digital Filter Design
SW300001-LT Digital Filter Design Lite
DS51442
“Digital Filter Design/Digital Filter Design Lite” (Available at: www.microchip.com)