msp430的24位AD使用问题

gandong

Other Parts Discussed in Thread: MSP430AFE253, MSP430F4270

1、我用到高精度24位AD，我主要参考官方例程，发现MSP430F4270的例程中有过采样率1024的，但是只读出低十六位。我想用msp430afe253读出24位AD数应该怎么改造。
请把下面代码改造成msp430afe253的24位精度的例程。

2、下图是430指南的截图，我的问题是两次读取，重叠的部分怎么处理？

代码如下
MSP430F4270
//     -----------------
// /|\|      XIN|-
// | |         | 32kHz
// --|RST XOUT|-
//    |         |
// Vin+ -->|A0+      |
// Vin- -->|A0-      |
//    |         |
//    |    VREF |---+
//    |         | |
//    |         | -+- 100nF
//    |         | -+-
//    |         | |
//    |    AVss |---+
//    |         |
//
// L. Westlund / S. Karthikeyan
// Texas Instruments Inc.
// June 2005
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.30A
//*****************************************************************************
#include <msp430.h>

unsigned int result;

int main(void)
{
volatile unsigned int i;          // Use volatile to prevent removal
                                    // by compiler optimization

WDTCTL = WDTPW + WDTHOLD;         // Stop WDT
FLL_CTL0 |= XCAP14PF;             // Configure load caps
for (i = 0; i < 10000; i++);      // Delay for 32 kHz crystal to
                                    // stabilize

SD16CTL = SD16REFON+SD16SSEL0;    // 1.2V ref, SMCLK
SD16CCTL0 |= SD16SNGL+SD16IE+SD16XOSR+SD16OSR0;// Single conv, enable interrupt, 1024 OSR
SD16INCTL0 |= SD16INTDLY_0;       // Interrupt on 4th sample
for (i = 0; i < 0x3600; i++);     // Delay for 1.2V ref startup

_EINT();                          // Enable general interrupts

while (1)
{
SD16CCTL0 |= SD16SC;            // SET BREAKPOINT HERE
                                    // Set bit to start conversion
_BIS_SR(LPM0_bits);             // Enter LPM0
}
}

#pragma vector=SD16_VECTOR
__interrupt void SD16ISR(void)
{
switch (SD16IV)
{
case 2:                           // SD16MEM Overflow
break;
case 4:                           // SD16MEM0 IFG
result = SD16MEM0;              // Save CH0 results (clears IFG)
break;
}

_BIC_SR_IRQ(LPM0_bits);           // Exit LPM0
}

11 年多前

0 gandong 11 年多前

Prodigy 90 points

？？？？

0 Nathan Zaker 11 年多前

Prodigy 30 points

1.AFE253自带24位Sigma Delta ADC，而F4270为16位SD，我想可以直接使用24位AD。

例程：http://www.ti.com/lit/zip/slac487

范例：

//*****************************************************************************
// MSP430AFE25x Demo - SD24, Continuous Conversion on a Group of 3 Channels
//
// Description: This program uses the SD24 module to perform continuous
// conversions on a group of channels (0, 1 and 2). A SD24 interrupt occurs
// whenever the conversions have completed. Test by applying voltages to the
// 3 input channels and setting a breakpoint at the line indicated
// below. Run program until it reaches the breakpoint, then use
// the debugger's watch window to view the conversion results. Results
// (upper 16 bits only) are stored in three arrays, one for each channel.
// ACLK = n/a, MCLK = SMCLK = DCO = ~ 1.1MHz
// //* For minimum Vcc required for SD24 module - see datasheet *//
// //* 100nF cap btw Vref and AVss is recommended when using 1.2V ref *//
//
// MSP430AFE25x
// -----------------
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// Vin1+ -->|A0.0+ |
// Vin1- -->|A0.0- |
// Vin2+ -->|A1.0+ |
// Vin2- -->|A1.0- |
// Vin3+ -->|A2.0+ |
// Vin3- -->|A2.0- |
// | VREF |---+
// | | |
// | | -+- 100nF
// | | -+-
// | | |
// | AVss |---+
// | |
//
// Naveen Kala
// Texas Instruments, Inc
// March 2011
// Built with IAR Embedded Workbench Version: 5.20.1
//*****************************************************************************
#include <msp430afe253.h>

#define Num_of_Results 8

/* Arrays to store SD24 conversion results */
unsigned int Ch0results[Num_of_Results];
unsigned int Ch1results[Num_of_Results];
unsigned int Ch2results[Num_of_Results];

void main(void)
{
volatile unsigned int i; // Use volatile to prevent removal
// by compiler optimization

WDTCTL = WDTPW + WDTHOLD; // Stop WDT

P1DIR |= BIT0+BIT1; // Set P1.0, P1.1 to output
SD24CTL = SD24REFON + SD24SSEL0; // 1.2V ref, SMCLK
SD24CCTL0 |= SD24GRP+SD24DF; // Group with CH1
SD24CCTL1 |= SD24GRP+SD24DF; // Group with CH2
SD24CCTL2 |= SD24IE+SD24DF; // Enable interrupt
for (i = 0; i < 0x3600; i++); // Delay for 1.2V ref startup

SD24CCTL2 |= SD24SC; // Set bit to start conversion
__bis_SR_register(LPM0_bits + GIE); // Enter LPM0 w/ interrupts
}

#pragma vector=SD24_VECTOR
__interrupt void SD24AISR(void)
{
static unsigned int index = 0;

switch (SD24IV)
{
case 2: // SD24MEM Overflow
break;
case 4: // SD24MEM0 IFG
break;
case 6: // SD24MEM1 IFG
break;
case 8: // SD24MEM2 IFG
Ch0results[index] = SD24MEM0; // Save CH0 results (clears IFG)
Ch1results[index] = SD24MEM1; // Save CH1 results (clears IFG)
Ch2results[index] = SD24MEM2; // Save CH2 results (clears IFG)
P1OUT ^=BIT0;
if (++index == Num_of_Results)
{
index = 0; // SET BREAKPOINT HERE
P1OUT ^=BIT1;
}
break;
}
}

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msp430的24位AD使用问题