ce200_readme.txt

pic24单片机程序示例

		Readme File for Code Example:
              CE200 - ADC Sampling and IIR Filtering 
             ----------------------------------------

This file contains the following sections:
1. Code Example Description
2. Folder Contents
3. Suggested Development Resources
4. Reconfiguring the project for a different PIC24H device
5. Revision History


1. Code Example Description:
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In this example, ADC is configured to sample (AIN5) at 8Khz rate and coverted data is assembled as 256 sample buffer before triggering filtering operation.

Timer 3 is setup to time-out every 125 microseconds (8Khz Rate). 
As a result, the module will stop sampling and trigger a 12-bit A/D conversion on every Timer3 time-out, i.e., Ts=125us. 
At that time, the conversion process starts and completes Tc=14*Tad periods later.
When the conversion completes, the module starts sampling again. However, since Timer3 
is already on and counting, about (Ts-Tc)us later, Timer3 will expire again and trigger 
next conversion. 

ADC module clock time period is configured as Tad=Tcy*(ADCS+1)= (1/40M)*64 = 1.6us (625Khz). 
Hence the conversion time for 12-bit A/D Conversion Time Tc=14*Tad = 22.4us

void initTmr3();
Timer 3 is configured to time-out at 8Khz rate. 

void initAdc1(void);
ADC module is set-up to convert AIN5 input using CH0 S/H on Timer 3 event in 12-bit mode.

void initDma0(void);
DMA channel 0 is confiured in ping-pong mode to move the converted data from ADC to DMA RAM on every sample/convert sequence. 
It generates interrupt after every 16 sample transfer. 

void __attribute__((__interrupt__)) _DMA0Interrupt(void);
DMA interrupt service routine, moves the data from DMA buffer to ADC signal buffer and collects 256 samples before initiating filtering function. 
Filtering is performed in the background loop. 




2. Folder Contents:
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This folder contains the following sub-folders:
a. C:\Program Files\Microchip\MPLAB C30\support\gld
        This folder will have the device GLD file, it is used for building the project. 
	This file was provided with the MPLAB