DM300014 Microchip Technology, DM300014 Datasheet - Page 34

• Manufacturer Part Number: DM300014
• Description: BOARD DEMO DSPICDEM 1.1 GEN PURP
• Manufacturer: Microchip Technology

Specifications of DM300014

• Processor To Be Evaluated: PIC30F
• Data Bus Width: 16 bit
• Interface Type: RS-485, CAN, SPI
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

dsPICDEM™ 1.1 Development Board User’s Guide
DS70099B-page 30
3.3.1.2
From the Menu Options display, pressing switch SW3 launches the DSP Operations
demo, which displays the digital signal values shown in Figure 3-6. This display
provides information on the various signal-processing operations that are performed on
the signal at analog input pin, AN3.
FIGURE 3-6:
The DSP operations display shows several parameters for a sampled sinewave signal.
A fundamental sinewave signal is generated by stepping the MCP41010 digital
potentiometer (U9) output at an 8 kHz rate. The output of the digital potentiometer is
applied to a low-pass (LP) filter with a cutoff frequency of approximately 4 kHz. This LP
filter removes the high-frequency components and yields a sinewave adequate for this
demonstration. Five frequencies are developed and selected by varying potentiometer
RP1, as shown in Table 3-1.
TABLE 3-1:
The filtered output of the MCP41010 is routed to pin AN3/RB3, which is an input to the
dsPIC30F 12-bit A/D converter. The A/D converter collects 256 samples from the
MCP41010 at an 8 kHz sample rate. These samples are optionally subjected to a digital
filtering algorithm implemented on the dsPIC30F. The following three digital filtering
options are provided and selected by switch SW2:
• None
• Infinite Impulse Response (IIR)
• Finite Impulse Response (FIR)
Subsequently, their spectral components are estimated. The frequency estimate of the
signal on pin AN3/RB3 is displayed on the first row of the DSP Operations display.
DSP OPERATIONS MODE
Potentiometer Setting
0 ≤ RP1 ≤ 1V
1 ≤ RP1 ≤ 2V
2 ≤ RP1 ≤ 3V
3 ≤ RP1 ≤ 4V
4 ≤ RP1 ≤ 5V
FREQUENCIES VS. POTENTIOMETER SETTING
Advance Information
DSP OPERATIONS DISPLAY
F = 1000
256
I I R
MAIN
PT
– s1
T
T
FILT
FFT
CHNGFILT
=018175
=028649
B
IN
= 032
–
Resulting Frequency
CY
CY
S
2
 2003 Microchip Technology Inc.
1000 Hz
1500 Hz
2000 Hz
100 Hz
500 Hz