DM300019 Microchip Technology, DM300019 Datasheet - Page 33

• Manufacturer Part Number: DM300019
• Description: BOARD DEMO DSPICDEM 80L STARTER
• Manufacturer: Microchip Technology
• Type: MCUr

Specifications of DM300019

• Contents: Board, CD, Sample Part
• Processor To Be Evaluated: dsPIC30F and dsPIC33F
• Interface Type: RS-232
• Silicon Manufacturer: Microchip
• Silicon Core Number: DsPIC30F6014A, DsPIC33FJ256GP710
• Silicon Family Name: DsPIC30F And DsPIC33F
• Kit Contents: Development Board And Docs On CD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: dsPIC30F, dsPIC33F
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

© 2006 Microchip Technology Inc.
3.4.3
This program uses Digital Potentiometer MCP41010 on the dsPICDEM 80-Pin Starter
Development Board as a D/A converter to generate a sine-wave signal (audio tone) to
the LINE OUT pin. The digital potentiometer is driven by the output of the serial
peripheral interface SPI2 of the dsPIC30F6014A device, which receives its input from
the program.
The program retrieves HEX values from a table in data memory and delivers it to the
SPI. Thirty-two stored values cover the full range of the digital potentiometer. As the
analog output of the digital potentiometer passes through the MCP6022 Operational
Amplifier (configured as a low-pass filter) it results in a 400 Hz sine wave based on a
new table value every 125 μsec covering all 32 table values. The sine wave is placed
on the LINE OUT pin of the development board.
Figure 3-3 illustrates the digital-to-analog conversion process. Switches S1 and S2 are
used to change the output frequency to 800 Hz and 1600 Hz, respectively, by skipping
over some of the table values.
FIGURE 3-3:
Digital-to-Analog Conversion
No
Set Reg W2 to Start of Tone Table
Set Reg W3 to End of Tone Table
Set Reg W1 = W2
Set W4 = Value Pointed to by
Transmit Contents of W4 to
Has 150 μsec Interrupt
Set W1 = W1 + 2
Set W1 = W1 + 2
DIGITAL-TO-ANALOG CONVERSION PROGRAM FLOW
W1 Using PSV
Set W1 = W2
S1 Pressed?
W1 > W3?
Occurred?
INIT SPI2
START
SPI2
Yes
Yes
Yes
Demonstration Program Operation
No
No
Set W1 = W1 + 4
S2 Pressed?
Yes
DS51584B-page 29
No