DSPIC33EP ADC配置它是在12位模式但转换发生在10位

您好，这是我在Microchip论坛上的第一篇文章，我非常感谢大家的帮助。我目前使用的是DSPIC33 EP512MC204微控制器，我在ADC功能方面遇到了一些问题。我配置它是在12位模式，但转换发生在10位（ADC1BUF0只包含10位）。电压基准是3.3V，而我正在接收的值确认我处于10位模式。我检查了配置寄存器和勘误表，但是我的init函数对于12位模式似乎是正确的。我尝试用10位模式配置它，同样的问题也出现了：在转换之后，我只接收8位。我需要12位来增加我的应用程序的分辨率。我正在使用的代码（见下面）是我为适应我的应用而定制的一个例子。谢谢你的帮助。玛丽



      以下为原文

    Hello, this is my first post on the Microchip forum and I thank you all in advance for your help.


I'm currently using DSPIC33EP512MC204 microcontroller and I'm experiencing some issues with the ADC feature. I configure it to be in 12 bits mode but the conversion is occuring in 10 bits (ADC1BUF0 contains only 10 bits). The voltage reference is 3.3V and the values I'm receiving confirm that I'm in a 10 bits mode. I checked the config registers and the errata but my init function seems right for a 12 bits mode. I tried to configure it in a 10 bits mode and the same problem is appearing: I receive only 8 bits after the conversion. I need 12 bits to increase the resolution of my application.

The code I'm using (see below) is an example I customed to fit my application.

#include
#include
#include "main.h"
#include "adcdrv2.h"
#include "tglpin.h"

// *****************************************************************************
// *****************************************************************************
// Section: File Scope or Global Constants
// *****************************************************************************
// *****************************************************************************
/* This section defines the input and the output buffers having a integer data type.
The input buffers are stored in either the extended data space or the x-memory area
depending on whether the extended data space (EDS) is available in the given dsPIC33E device.
*/
#ifdef _HAS_DMA_
__eds__ int bufferA[NUMSAMP] __attribute__( (eds, space(dma)) );
__eds__ int bufferB[NUMSAMP] __attribute__( (eds, space(dma)) );
#else
int bufferA[NUMSAMP] __attribute__( (space(xmemory)) );
int bufferB[NUMSAMP] __attribute__( (space(xmemory)) );
#endif
void ProcessADCSamples( __eds__ int *adcBuffer );

/******************************************************************************
* Function: void InitAdc1(void)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: None
*
* Overview: This function is used to configure A/D to convert channel 5 on Timer event.
                    It generates event to DMA on every sample/convert sequence. ADC clock is configured at 625Khz.
*****************************************************************************/
void InitAdc1( void )
{
    AD1CON1bits.AD12B = 1; // 12 bits mode
    AD1CON1bits.FORM = 0; // Data Output Format: Integer
    AD1CON1bits.SSRC = 7; // Interan Counter (SAMC) ends sampling and starts convertion
    AD1CON1bits.SIMSAM = 0;
    AD1CON1bits.ASAM = 1; // ADC Sample Control: Sampling begins immediately after conversion
    AD1CON2bits.CHPS = 0; // Converts CH0/CH1
    AD1CON3bits.ADRC = 0; // ADC Clock is derived from Systems Clock
    AD1CON3bits.SAMC = 0; // Auto Sample Time = 0*Tad
    AD1CON3bits.ADCS = 30; // ADC Conversion Clock

    AD1CON1bits.ADDMABM = 1; // DMA buffers are built in conversion order mode
    AD1CON2bits.SMPI = 0; // SMPI must be 0
    AD1CON4bits.ADDMAEN = 1; // Converts in ADC1BUF0


    AD1CHS0bits.CH0SA = 2; // MUXA +ve input selection (AIN20) for CH0
    AD1CHS0bits.CH0NA = 0; // MUXA -ve input selection (Vref-) for CH0

    AD1CHS0bits.CH0NB = 0;
    AD1CHS0bits.CH0SB = 0b000001;
    IFS0bits.AD1IF = 0; // Clear the A/D interrupt flag bit
    IEC0bits.AD1IE = 0; // Do Not Enable A/D interrupt
    AD1CON1bits.ADON = 1; // Turn on the A/D converter
}

/******************************************************************************
* Function: void InitDma0(void)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: None
*
* Overview: DMA0 configuration function.
                    Direction: Read from peripheral address 0-x300 (ADC1BUF0) and write to DMA RAM
                    AMODE: Register indirect with post increment
                    MODE: Continuous, Ping-Pong Mode
                    IRQ: ADC Interrupt
                    ADC stores results stored alternatively between DMA_BASE[0]/DMA_BASE[16] on every
                    16th DMA request
*****************************************************************************/
void InitDma0( void )
{
    DMA0CONbits.AMODE = 0; // Configure DMA for Register indirect with post increment
    DMA0CONbits.MODE = 2; // Configure DMA for Continuous Ping-Pong mode
    DMA0PAD = ( int ) &ADC1BUF0;
    DMA0CNT = ( NUMSAMP - 1 );

    DMA0REQ = 13;

    #ifdef _HAS_DMA_
    DMA0STAL = __builtin_dmaoffset( &bufferA );
    DMA0STAH = __builtin_dmapage( &bufferA );

    DMA0STBL = __builtin_dmaoffset( &bufferB );
    DMA0STBH = __builtin_dmapage( &bufferB );

    #else
    DMA0STAL = ( unsigned int ) &bufferA;
    DMA0STAH = ( unsigned int ) &bufferA;

    DMA0STBL = ( unsigned int ) &bufferB;
    DMA0STBH = ( unsigned int ) &bufferB;
    #endif
    IFS0bits.DMA0IF = 0; //Clear the DMA interrupt flag bit
    IEC0bits.DMA0IE = 1; //Set the DMA interrupt enable bit
    DMA0CONbits.CHEN = 1;
}

unsigned int dmaBuffer = 0;
#ifdef TEST_MODE
        unsigned char test_flag_buffA=0;
        unsigned char test_flag_buffB=0;
#endif
/******************************************************************************
* Function: void __attribute__((interrupt, auto_psv)) _DMA0Interrupt(void)
*
* PreCondition: None
*
* Input: None
*
* Output: None
*
* Side Effects: None
*
* Overview: Depending on the dmaBuffer value, the data in bufferA or bufferB is passed
*****************************************************************************/
void __attribute__ ( (interrupt, auto_psv) ) _DMA0Interrupt( void )
{
    if( dmaBuffer == 0 )
    {
#ifdef TEST_MODE
        test_flag_buffA=1;
#endif
        ProcessADCSamples( bufferA );
    }
    else
    {
#ifdef TEST_MODE
        test_flag_buffB=1;
#endif
        ProcessADCSamples( bufferB );
    }
    dmaBuffer ^= 1;
    IFS0bits.DMA0IF = 0; //Clear the DMA0 Interrupt Flag
}

End of File
*/


Thanks for your help.

Marie

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