DM300014 Microchip Technology, DM300014 Datasheet - Page 39

• 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

 2003 Microchip Technology Inc.
3.4.2
The step-by-step Main Loop execution sequence is shown in Table 3-4.
TABLE 3-4:
Seq
10
11
1
2
3
4
5
6
7
8
9
Main Loop Code Execution
12-bit ADC collects 256 samples from the digital potentiometer output on AN3 into
a RAM buffer.
Buffered data set is filtered using an IIR filter to remove line noise. The filter can
be changed to an FIR filter or no filter from the DSP menu options. The filtering
operation is benchmarked using the Timer4/5 pair.
A complex in-place 256-point FFT is performed on the filtered data set, resulting
in complex frequency data (x + jy). This operation is benchmarked using the
Timer4/5 pair.
Squared magnitude is computed for each frequency bin in an in-place fashion
(x
The magnitude data is run through a routine that returns the frequency bin and
magnitude of the largest element.
The magnitude of the largest element is compared against a threshold and
captured if it is greater than the threshold so that low-level noise does not show
up as a frequency estimate. (Provides a simplified peak-detection algorithm.)
The ADC settings are changed to sample pins AN4 (RP2), AN5 (RP3), AN6
(RP1) and AN8 (temperature sensor U9). One sample of each is recorded and
the ADC is reconfigured for the initial settings.
If a Timer3 count has expired, a software flag is set to inform the CPU that the
results recorded may now be displayed. This ensures that the CPU refreshes the
display buffers.
Any user choices entered via the switches SW1-SW4 are checked and the new
user selections are applied. May involve a change of display screen or some
parameter displayed on the LCD.
The changes are communicated to the PIC18F242 LCD controller via the SPI 2
module.
In the special case of the DTMF menu, the main routine may also kick off the DCI
module operation when the user requests DTMF tone generation.
2
+ y
MAIN LOOP CODE EXECUTION SEQUENCE
2
Demonstration Program Operation
).
Advance Information
Program Task
DS70099B-page 35