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dsPICDEM™ 1.1 Plus Development Board User’s Guide
DS70099D-page 30
©
2006 Microchip Technology Inc.
FIGURE 3-2:
DEMO MENU OPTIONS
From this menu you can choose one of three demonstration modes:
• Data Acquisition Display mode
• Digital Signal Processing (DSP) Operations mode
• Dual Tone Multi-Frequency (DTMF) Generation mode
3.3.1.1
DATA ACQUISITION DISPLAY MODE
The Data Acquisition Display mode demonstrates the capability of the dsPIC30F
device to convert inputs from five different analog signal sources at varying sampling
rates.
Data Acquisition mode is initiated by pressing switch SW2. Figure 3-3 shows the
resulting display on the LCD.
FIGURE 3-3:
DATA ACQUISITION DISPLAY
This display shows the values of the following analog signal sources:
• Potentiometers RP1-RP3
The three potentiometers available on the dsPICDEM™ 1.1 Plus Development
Board, RP1, RP2 and RP3, are connected to analog input pins AN6, AN4 and
AN5, respectively, on the dsPIC30F device.
• Temperature Sensor U9:
Temperature sensor, TC1047A, is connected to the analog input pin, AN8, on the
dsPIC30F device.
• Frequency:
A fundamental sine-wave signal is generated by stepping the MCP41010 digital
potentiometer (U8) output at an 8 kHz rate. The analyzed frequency is displayed
on the LCD.
The 12-bit ADC on the dsPIC30F device is used to convert these analog input sources.
To estimate the frequency of the generated sine-wave signal, the program converts and
buffers 256 samples of the signal on pin AN3 and then performs a Fast-Fourier
Transform (FFT) on the buffer. The ADC is interrupt driven to sample and convert at a
16 kHz rate for this operation. AN3 is converted on every alternate conversion, thus
delivering an effective sampling rate of 8 kHz for the signal presented at AN3.
The program scans input pins AN4, AN5, AN6 and AN8 to sample and convert the
values of the temperature sensor and potentiometer signals and delivers one sample
of each of these signals to the LCD display.
M
ENU
O
PTIONS
D
ATA
A
CQ
D
ISPLAY
– S2
DSP O
PERATIONS
– S3
DTMF G
ENERATION
– S4
F = 1000
HZ
T
EMP
= +23
DG
C
RP1 = 1.67
V
RP2 = 2.95
V
RP3 = 2.62
V
MAIN
– s1
Содержание dsPICDEM 1.1 Plus
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