dsp281x_adc.c

tms320f2812例子程序

//###########################################################################
//
// FILE:	DSP281x_Adc.c
//
// TITLE:	DSP281x ADC Initialization & Support Functions.
//
//###########################################################################
//
//  Ver | dd mmm yyyy | Who  | Description of changes
// =====|=============|======|===============================================
//  1.00| 11 Sep 2003 | L.H. | Changes since previous version (v.58 Alpha)
//      |             |      | ADC_usDELAY changed from 5000L to 8000L
//###########################################################################

#include "DSP281x_Device.h"     // DSP281x Headerfile Include File
#include "DSP281x_Examples.h"   // DSP281x Examples Include File

#define ADC_usDELAY  8000L
#define ADC_usDELAY2 20L

//---------------------------------------------------------------------------
// InitAdc: 
//---------------------------------------------------------------------------
// This function initializes ADC to a known state.
//
void InitAdc(void)
{
	extern void DSP28x_usDelay(Uint32 Count);
	
    // To powerup the ADC the ADCENCLK bit should be set first to enable
    // clocks, followed by powering up the bandgap and reference circuitry.
    // After a 5ms delay the rest of the ADC can be powered up. After ADC
    // powerup, another 20us delay is required before performing the first
    // ADC conversion. Please note that for the delay function below to
    // operate correctly the CPU_CLOCK_SPEED define statement in the
    // DSP28_Examples.h file must contain the correct CPU clock period in
    // nanoseconds. For example:

	AdcRegs.ADCTRL3.bit.ADCBGRFDN = 0x3;	// Power up bandgap/reference circuitry
	DELAY_US(ADC_usDELAY);                  // Delay before powering up rest of ADC
	AdcRegs.ADCTRL3.bit.ADCPWDN = 1;		// Power up rest of ADC
	DELAY_US(ADC_usDELAY2);                 // Delay after powering up ADC
}	

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// No more.
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