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Join our teamThe ColdFire® DSP Library contains digital signal processing algorithms optimized for the ColdFire architecture. These algorithms are implemented directly in assembly for computational efficiency and then encapsulated into a simple C interface. In addition, a large number of predefined and pretested filter configurations are provided in order to reduce the need for a user to design digital filters.
The library is designed to enable embedded sensor applications with basic signal processing functionality, but without the need for a DSP co-processor. By taking advantage of an on-chip multiply-accumulate unit (MAC), a ColdFire microcontroller can efficiently execute DSP algorithms.
Parameter | Options | Implications |
Shape | lowpass, highpass, bandpass, notch | Shape of frequency response, i.e., are high frequencies passed through or attenuated |
Order | 2,3,4,5,6 | Rolloff steepness. Higher orders roll off faster but require more MCU bandwidth |
Cutoff | varies by order, most cover 0.20-0.80 range in 0.05 increments | Digital cutoff frequency (-3dB). Related to analog frequency by sample rate, |
The following table identifies all filter configurations included in the library. Each combination of filter shape, order and cutoff constitutes a single filter configuration. Each configuration comes with four parameters – filter coefficients array, numerator scale factor, denominator scale factor, and filter order. The configurations below are all characterized as Butterworth IIR filters.
Shape | Order | Minimum Cutoff | Cutoff Increment | Maximum Cutoff |
Lowpass | 2 | 0.20 | 0.05 | 0.85 |
3 | 0.20 | 0.05 | 0.85 | |
4 | 0.25 | 0.05 | 0.80 | |
5 | 0.25 | 0.05 | 0.80 | |
6 | 0.25 | 0.05 | 0.75 | |
Highpass | 2 | 0.20 | 0.05 | 0.80 |
3 | 0.20 | 0.05 | 0.80 | |
4 | 0.25 | 0.05 | 0.75 | |
5 | 0.25 | 0.05 | 0.75 | |
6 | 0.25 | 0.05 | 0.75 | |
Bandpass | 4 | 0.20 | 0.05 | 0.80 |
Notch | 4 | 0.20 | 0.05 | 0.80 |
Parameter | Options | Implications |
Shape | lowpass, highpass, bandpass, notch | Shape of frequency response, i.e., are high frequencies passed through or attenuated |
Order | 2,3,4,5,6 | Rolloff steepness. Higher orders roll off faster but require more MCU bandwidth |
Cutoff | varies by order, most cover 0.20-0.80 range in 0.05 increments | Digital cutoff frequency (-3dB). Related to analog frequency by sample rate, |
The following table identifies all filter configurations included in the library. Each combination of filter shape, order and cutoff constitutes a single filter configuration. Each configuration comes with four parameters – filter coefficients array, numerator scale factor, denominator scale factor, and filter order. The configurations below are all characterized as Butterworth IIR filters.
Shape | Order | Minimum Cutoff | Cutoff Increment | Maximum Cutoff |
Lowpass | 2 | 0.20 | 0.05 | 0.85 |
3 | 0.20 | 0.05 | 0.85 | |
4 | 0.25 | 0.05 | 0.80 | |
5 | 0.25 | 0.05 | 0.80 | |
6 | 0.25 | 0.05 | 0.75 | |
Highpass | 2 | 0.20 | 0.05 | 0.80 |
3 | 0.20 | 0.05 | 0.80 | |
4 | 0.25 | 0.05 | 0.75 | |
5 | 0.25 | 0.05 | 0.75 | |
6 | 0.25 | 0.05 | 0.75 | |
Bandpass | 4 | 0.20 | 0.05 | 0.80 |
Notch | 4 | 0.20 | 0.05 | 0.80 |