多个IO口采ADC的问题

2019-03-24 08:58发布

站内问答 / TI MCU
15776 3 1498
请教各位： 使用MSP430FR5969


我使用P3.0  （A12） 、 P3.2  (A14)、P3.3 (A15 )  三个IO口，分别采三个ADC，但是都是以第一个采到的ADC的值为准，不会变化

P3.0采2.0V的电压，P3.2采0.5V的电压 P3.3采1.0V的电压，最后得到的结果总是以P3.0的值为准

但是单次分别采各自的电压是正确的，就是3个IO口一起采的时候，会出现这种情况。

请问是通道没有转换所以一直以第一个通道来采电压吗？还是有其他可能？

请教大家，谢谢！

下面是ADC的初始化和采ADC函数代码

  1. void init_adc()
  2. {
  3. //Initialize the ADC12B Module
  4. /*
  5. * Base address of ADC12B Module
  6. * Use internal ADC12B bit as sample/hold signal to start conversion
  7. * USE MODOSC 5MHZ Digital Oscillator as clock source
  8. * Use default clock divider/pre-divider of 1
  9. * Not use internal channel
  10. */
  11. ADC12_B_initParam initParam = {0};
  12. initParam.sampleHoldSignalSourceSelect = ADC12_B_SAMPLEHOLDSOURCE_SC;
  13. initParam.clockSourceSelect = ADC12_B_CLOCKSOURCE_ADC12OSC;
  14. initParam.clockSourceDivider = ADC12_B_CLOCKDIVIDER_1;
  15. initParam.clockSourcePredivider = ADC12_B_CLOCKPREDIVIDER__1;
  16. initParam.internalChannelMap = ADC12_B_NOINTCH;
  17. ADC12_B_init(ADC12_B_BASE, &initParam);

  19. //Enable the ADC12B module
  20. ADC12_B_enable(ADC12_B_BASE);

  22. /*
  23. * Base address of ADC12B Module
  24. * For memory buffers 0-7 sample/hold for 64 clock cycles
  25. * For memory buffers 8-15 sample/hold for 4 clock cycles (default)
  26. * Disable Multiple Sampling
  27. */
  28. ADC12_B_setupSamplingTimer(ADC12_B_BASE, ADC12_B_CYCLEHOLD_16_CYCLES,
  29. ADC12_B_CYCLEHOLD_4_CYCLES, ADC12_B_MULTIPLESAMPLESDISABLE);

  31. //Configure Memory Buffer
  32. /*
  33. * Base address of the ADC12B Module
  34. * Configure memory buffer 0
  35. * Map input A3 to memory buffer 0
  36. * Vref+ = AVcc
  37. * Vref- = AVss
  38. * Memory buffer 0 is not the end of a sequence
  39. */
  40. ADC12_B_configureMemoryParam configureMemoryParam = {0};
  41. configureMemoryParam.memoryBufferControlIndex = ADC12_B_MEMORY_0;
  42. //        configureMemoryParam.inputSourceSelect = ADC12_B_INPUT_A3;
  43. configureMemoryParam.refVoltageSourceSelect =
  44. ADC12_B_VREFPOS_AVCC_VREFNEG_VSS;
  45. configureMemoryParam.endOfSequence = ADC12_B_NOTENDOFSEQUENCE;
  46. configureMemoryParam.windowComparatorSelect =
  47. ADC12_B_WINDOW_COMPARATOR_DISABLE;
  48. configureMemoryParam.differentialModeSelect =
  49. ADC12_B_DIFFERENTIAL_MODE_DISABLE;
  50. ADC12_B_configureMemory(ADC12_B_BASE, &configureMemoryParam);

  52. ADC12_B_clearInterrupt(ADC12_B_BASE, 0, ADC12_B_IFG0);
  53. //Enable memory buffer 0 interrupt
  54. ADC12_B_enableInterrupt(ADC12_B_BASE, ADC12_B_IE0, 0, 0);
  55. }
复制代码
  1. uint16_t ADC12_B_Sampling(uint16_t GpioPort, uint16_t GpioPin, uint16_t InputSource)
  2. {

  4. int16_t i16Adcdata[16];
  5. int16_t i16swap = 0;
  6. int16_t i16_temp = 0, i16_temp1 = 0;

  8. GPIO_setAsPeripheralModuleFunctionOutputPin(GpioPort, GpioPin,
  9. GPIO_TERNARY_MODULE_FUNCTION);

  11. HWREG16(ADC12_B_BASE + OFS_ADC12MCTL0 + ADC12_B_MEMORY_0) = InputSource; //Set Input Source

  13. //        __bic_SR_register(GIE);
  14. _disable_interrupts();

  16. for (i = 0; i < 16; i++)
  17. {
  18. // 开始采样和转化，在memory buffer 0 ，单通道单次转化
  19. ADC12_B_startConversion(ADC12_B_BASE, ADC12_B_MEMORY_0,
  20. ADC12_B_SINGLECHANNEL);

  22. while (!(HWREG8(ADC12_B_BASE + OFS_ADC12IFGR0) & ADC12IFG0));
  23. ADC_Get_Value = ADC12_B_getResults(ADC12_B_BASE, ADC12_B_MEMORY_0);
  24. HWREG16(ADC12_B_BASE + (OFS_ADC12MEM0 + ADC12_B_MEMORY_0)) = 0;
  25. i16Adcdata[i] = ADC_Get_Value;

  27. __no_operation();
  28. __delay_cycles(5000);
  29. }
  30. //        __bis_SR_register(GIE);
  31. _enable_interrupts();

  33. for (i16_temp = 0; i16_temp < 16; i16_temp++)
  34. {
  35. for (i16_temp1 = i16_temp + 1; i16_temp1 < 16; i16_temp1++)
  36. {
  37. if (i16Adcdata[i16_temp] < i16Adcdata[i16_temp1])
  38. {
  39. i16swap = i16Adcdata[i16_temp];
  40. i16Adcdata[i16_temp] = i16Adcdata[i16_temp1];
  41. i16Adcdata[i16_temp1] = i16swap;
  42. }
  43. }
  44. }

  46. for (i16_temp = 5; i16_temp < 12; i16_temp++)
  47. i16Adcdata[4] += i16Adcdata[i16_temp];
  48. i16Adcdata[4] += 8;
  49. i16Adcdata[4] = i16Adcdata[4] >> 3;
  50. ADV_Get_Aver_Value = i16Adcdata[4];


  53. //        DEBUG_PRINT(MSG_ALWAYS, "ADV_Get_Aver_Value=====%d ", ADV_Get_Aver_Value);

  55. return ADV_Get_Aver_Value;

  57. }
复制代码


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3条回答
gh131413
2019-03-24 15:54
< 转换通道和IO口切换再加切换时间延迟一般是没有问题的，再查查程序看有没有问题……

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