Readme File for Code Example:
Using Timer 3 to Start ADC
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This file contains the following sections:
1. Code Example Description
2. Folder Contents
3. Suggested Development Resources
4. Reconfiguring the project for a different PIC24F device
5. Revision History
1. Code Example Description:
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In this example, ADC is configured to sample (AIN5) at 4Khz rate and coverted data is assembled as 16 sample buffer before triggering filtering operation.
Timer 3 is setup to time-out every 250 microseconds (4Khz Rate).
As a result, the module will stop sampling and trigger a 10-bit A/D conversion on every Timer3 time-out, i.e., Ts = 250us.
At that time, the conversion process starts and completes Tc=12*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)= (1/8M)*64 = 8us (125Khz).
Hence the conversion time for 10-bit A/D Conversion Time Tc=12*Tad = 96us
void initTmr3();
Timer 3 is configured to time-out at 4Khz rate.
void initAdc1(void);
ADC module is set-up to convert AIN5 input using CH0 S/H on Timer 3 event in 10-bit mode.
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?C30 toolsuite.
b. C:\Program Files\Microchip\MPLAB C30\support\h
This folder contains C header files useful in building this
project. Device register and bit definitions are provided in
the *.h file that follows the device name. These files were provided
with the MPLAB?C30 toolsuite.
c. C:\Program Files\Microchip\MPLAB C30\lib
This folder contains library archive files, which are a
collection of precompiled object files. The file
named "libpic30-coff.a" contains the C run-time start-up
library. These file were provided with the
MPLAB?C30 toolsuite.
d. hex
This folder contains three file types - coff, hex and map.
These are files generated by the MPLAB?C30 toolsuite on build
operation performed within MPLAB?IDE. The *.map file contains
details on memory allocation for various variables, constants
and dsPIC instructions specified in the source and library
code. The *.hex file contains a binary file that may be
programmed into the dsPIC device. The *.coff file contains
a binary file that is used by MPLAB?IDE for simulation.
e. h
This folder contains include files for the code example.
f. src
This folder contains all the C and Assembler source files (*.c,
*.s) used in demonstrating the described example. This folder
also contains a sub-folder named "obj" that stores compiled
object files generated when the project is built.
3. Suggested Development Resources:
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a. Explorer 16 Demo board with PIC24FJ128GA010 controller
4. Reconfiguring the project for a different PIC24F device:
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The Project/Workspace can be easily reconfigured for any PIC24F device.
Please use the following general guidelines:
a. Change device selection within MPLAB?IDE to a PIC24F device of
your choice by using the following menu option:
MPLAB IDE>>Configure>>Select Device
b. Provide the correct device linker script and header file for your
device. Device linker scripts and header files are available in your
MPLAB?C30 installation folder under:
Device Linker Script-
YourDrive:>Program Files\Microchip\MPLAB C30\support\gld
Device C Header file-
YourDrive:>Program Files\Microchip\MPLAB C30\support\h
Device ASM Include file-
YourDrive:>Program Files\Microchip\MPLAB C30\support\inc
c. Provide the appropriate path to your MPLAB C30 support file locations
using the menu option:
MPLAB IDE>>Project>>Build Options>>Project
d. Chose the development board applicable to your device. Some options
are provided below:
e. Re-build the MPLAB?project using the menu option:
MPLAB IDE>>Project>>Build All
f. Download the hex file into the device and run.
5. Revision History :
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04/01/2008 - Initial Release of the Code Example