LPC5516_SDK例程ADC_2Msps高速采集

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LPC5516_SDK例程ADC_2Msps高速采集

最近支持一个客户，需要在LPC5516下实现ADC 2Msps高速采集，根据数据手册描述：

ADC在12-bit模式下最高可以达到2.3Msps
ADC在16-bit模式下最高可以达到2.0Msps.
那么实际情况是否真如数据手册所述，能达到如此高的转换速率呢？小编这次就编写了测试代码进行了实测，结果为：
12-bit模式下ADC最快可达2.326Msps,  16-bit模式下2.083Msps, 结果还是和数据手册很吻合的。

代码设计
代码基于SDK的例程：
\SDK_2_12_0_LPCXpresso55S16\boards\lpcxpresso55s16\driver_examples\lpadc\dma
修改：
1. 为了实现最快速度ADC采集，我们需要将ADC配置为：
ADC输入时钟: ADCCLK = 48MHz
无硬件平均: HWAVG=1
ADC采样时长设置为最短3xCLK:  STS=0
ADC功率最大: PWRSEL=3


除此之外，还需要将ADC设置为连续转换模式：即将g_LpadcCommandConfigStruct.chainedNextCommandNumber指向自己，即完成当前转换后，自动开始下次转换。


以上所有配置对应SDK代码如下：

1. /* Configure ADC. */
   
2.     LPADC_GetDefaultConfig(&lpadcConfigStruct);
   
3.     lpadcConfigStruct.enableAnalogPreliminary = true;
   
4.     lpadcConfigStruct.conversionAverageMode = kLPADC_ConversionAverage1;
   
5.     lpadcConfigStruct.powerLevelMode=kLPADC_PowerLevelAlt4;
   
6.     lpadcConfigStruct.referenceVoltageSource = DEMO_LPADC_VREF_SOURCE;
   
7.     lpadcConfigStruct.FIFO0Watermark = 2;

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1.    LPADC_GetDefaultConvCommandConfig(&g_LpadcCommandConfigStruct);
   
2.     g_LpadcCommandConfigStruct.channelNumber = DEMO_LPADC_USER_CHANNEL;
   
3.     g_LpadcCommandConfigStruct.sampleTimeMode = kLPADC_SampleTimeADCK3;
   
4.     g_LpadcCommandConfigStruct.loopCount = 1;
   
5.     g_LpadcCommandConfigStruct.conversionResolutionMode = kLPADC_ConversionResolutionHigh;
   
6.   // g_LpadcCommandConfigStruct.conversionResolutionMode =kLPADC_ConversionResolutionStandard;
   
7.     g_LpadcCommandConfigStruct.chainedNextCommandNumber = DEMO_LPADC_USER_CMDID;

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2. 配置DMA，使用DMA  Ping-Pang buffer接收ADC数据，即定义两个DMA描述符，A和B：A传输完成后自动触发B，B传输完成后自动触发A。对应SDK代码为：

1.   SDK_ALIGN(uint32_t s_dma_table[DMA_DESCRIPTOR_NUM * sizeof(dma_descriptor_t)], FSL_FEATURE_DMA_LINK_DESCRIPTOR_ALIGN_SIZE);
   
2. 2.
   
3. 3.   const uint32_t g_XferConfig =
   
4. 4.      DMA_CHANNEL_XFER(true,                         /* Reload linkdescriptor after current exhaust, */
   
5. 5.                      true,                         /* Clear trigger status.*/
   
6. 6.                      true,                         /* Enable interruptA. */
   
7. 7.                      false,                        /* Not enable interruptB. */
   
8. 8.                      sizeof(uint32_t),           /* Dma transfer width. */
   
9. 9.                      kDMA_AddressInterleave0xWidth, /* Dma source address no interleave */
   
10. 10.                      kDMA_AddressInterleave1xWidth, /* Dma destination address nointerleave  */
    
11. 11.                      sizeof(uint32_t)*ADC_DMA_SIZE              /* Dma transfer byte. */

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1. static void DMA_Configuration(void)
   
2. {
   
3.     dma_channel_config_t dmaChannelConfigStruct;
   
4. #if defined (DEMO_DMA_HARDWARE_TRIGGER) && DEMO_DMA_HARDWARE_TRIGGER
   
5.     /* Configure INPUTMUX. */
   
6.     INPUTMUX_Init(DEMO_INPUTMUX_BASE);
   
7.     INPUTMUX_AttachSignal(DEMO_INPUTMUX_BASE, DEMO_DMA_ADC_CHANNEL, DEMO_DMA_ADC_CONNECTION);
   
8. #endif /* DEMO_DMA_HARDWARE_TRIGGER */
   
9. 
   
10.     /* Configure DMA. */
    
11.     DMA_Init(DEMO_DMA_BASE);
    
12.     DMA_EnableChannel(DEMO_DMA_BASE, DEMO_DMA_ADC_CHANNEL);
    
13.     DMA_CreateHandle(&g_DmaHandleStruct,  DEMO_DMA_BASE,  DEMO_DMA_ADC_CHANNEL);
    
14.     DMA_SetCallback(&g_DmaHandleStruct, DEMO_DMA_Callback, NULL);
    
15. 
    
16. 
    
17.     /* Prepare and submitthe transfer. */
    
18.     DMA_PrepareChannelTransfer(&dmaChannelConfigStruct,             /* DMA channel transfer configuration structure. */
    
19.                               (void *)DEMO_LPADC_RESFIFO_REG_ADDR,  /* DMA transfer source address.*/
    
20.                               (void *)adc_result,             /* DMA transfer destination address. */
    
21.                               g_XferConfig,                        /* Xfer configuration */
    
22.                              kDMA_PeripheralToMemory,               /* DMAtransfer type. */
    
23.                               NULL,                                /*DMA channel trigger configurations. */
    
24.                               (dma_descriptor_t *)&(s_dma_table[0]) /* Address of next descriptor. */
    
25. 
    
26.     );
    
27.     DMA_SubmitChannelTransfer(&g_DmaHandleStruct, &dmaChannelConfigStruct);
    
28. 
    
29.     /* Set two DMAdescripters to use ping-pong mode.  */
    
30.     DMA_SetupDescriptor((dma_descriptor_t *)&(s_dma_table[0]), g_XferConfig, (void *)DEMO_LPADC_RESFIFO_REG_ADDR, (void *)adc_result, (dma_descriptor_t *)&(s_dma_table[4]));
    
31.     DMA_SetupDescriptor((dma_descriptor_t *)&(s_dma_table[4]), g_XferConfig, (void *)DEMO_LPADC_RESFIFO_REG_ADDR, (void *)adc_result, (dma_descriptor_t *)&(s_dma_table[0]));
    
32. 
    
33. }

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3. 最后小编还使能了SysTick定时器用于记录转换时间，程序开始运行后，ADC会启动连续转换，DMA设置为传输100次ADC转换结果后触发DMA完成中断,  DMA中断触发后(传输完成)，程序会统计ADC转换时间，计算ADC转换结果的平均值和标准差，以及打印转换结果。

代码清单


最后为大家呈上完整代码清单(可以直接复制到lpadc_dma.c里运行)：

1. /*
   
2. * Copyright 2018-2021 NXP
   
3. * All rights reserved.
   
4. *
   
5. *
   
6. * SPDX-License-Identifier: BSD-3-Clause
   
7. */
   
8. 
   
9. #include "pin_mux.h"
   
10. #include "clock_config.h"
    
11. #include "board.h"
    
12. #include "fsl_debug_console.h"
    
13. #include "fsl_dma.h"
    
14. #include "fsl_inputmux.h"
    
15. #include "fsl_lpadc.h"
    
16. #include "stdio.h"
    
17. #include "math.h"
    
18. #include "fsl_power.h"
    
19. #include "fsl_anactrl.h"
    
20. /*******************************************************************************
    
21. * Definitions
    
22. 
    
23. ******************************************************************************/
    
24. #define PF(a)   ((a) * (a))
    
25. #define DEMO_LPADC_BASE                  ADC0
    
26. #define DEMO_LPADC_USER_CHANNEL          0U
    
27. #define DEMO_LPADC_USER_CMDID            1U /* CMD1 */
    
28. #define DEMO_LPADC_VREF_SOURCE           kLPADC_ReferenceVoltageAlt2
    
29. #define DEMO_LPADC_DO_OFFSET_CALIBRATION true
    
30. #define DEMO_LPADC_RESFIFO_REG_ADDR      (uint32_t)(&(ADC0->RESFIFO[0]))
    
31. #define DEMO_RESULT_FIFO_READY_FLAG      kLPADC_ResultFIFO0ReadyFlag
    
32. 
    
33. #define DEMO_DMA_BASE          DMA0
    
34. #define DEMO_DMA_ADC_CHANNEL   21U
    
35. #define DMA_DESCRIPTOR_NUM 2U
    
36. #define ADC_DMA_SIZE        (100)
    
37. 
    
38. static void ADC_Configuration(void);
    
39. static void DMA_Configuration(void);
    
40. 
    
41. lpadc_conv_command_config_t g_LpadcCommandConfigStruct; /*
    
42. Structure to configure conversion command. */
    
43. 
    
44. dma_handle_t g_DmaHandleStruct;              /* Handler structure for using DMA. */
    
45. uint32_t adc_result[ADC_DMA_SIZE];                 /* Keep the ADC conversion resulut moved from ADC data register by DMA. */
    
46. static double adc_sum;
    
47. static double adc_mean, adc_std;
    
48. static double adc_sum_sqrt;
    
49. 
    
50. volatile bool g_DmaTransferDoneFlag = false; /* Flag of DMA transfer done trigger by ADC conversion. */
    
51. /* DMA descripter table used for ping-pong mode. */
    
52. SDK_ALIGN(uint32_t s_dma_table[DMA_DESCRIPTOR_NUM * sizeof(dma_descriptor_t)], FSL_FEATURE_DMA_LINK_DESCRIPTOR_ALIGN_SIZE);
    
53.           const uint32_t g_XferConfig =    DMA_CHANNEL_XFER(true,                          /* Reload link descriptor after current exhaust, */
    
54.                     true,                          /* Clear trigger status. */
    
55.                     true,                          /* Enable interruptA. */
    
56.                     false,                         /* Not enable interruptB. */
    
57.                     sizeof(uint32_t),            /* Dma transfer width. */
    
58.                     kDMA_AddressInterleave0xWidth, /* Dma source address no interleave  */
    
59.                     kDMA_AddressInterleave1xWidth, /* Dma destination address no interleave  */
    
60.                     sizeof(uint32_t)*ADC_DMA_SIZE               /* Dma transfer byte. */
    
61.    );
    
62. 
    
63. const uint32_t g_LpadcFullRange   = 65536U;
    
64. const uint32_t g_LpadcResultShift = 0U;
    
65. 
    
66.                     void DEMO_DMA_Callback(dma_handle_t *handle, void *param, bool transferDone, uint32_t tcds)
    
67. {
    
68.    //printf("DEMO_DMA_Callback\r\n");
    
69.    if (true == transferDone)
    
70.    {
    
71.        g_DmaTransferDoneFlag = true;
    
72.    }
    
73. }
    
74. 
    
75. int main(void)
    
76. {
    
77.    /* Initialize board hardware. */
    
78.    /* set BOD VBAT level to 1.65V */
    
79.    POWER_SetBodVbatLevel(kPOWER_BodVbatLevel1650mv, kPOWER_BodHystLevel50mv, false);
    
80.    /* attach main clock divide to FLEXCOMM0 (debug console) */    CLOCK_AttachClk(BOARD_DEBUG_UART_CLK_ATTACH);    BOARD_InitBootPins();    BOARD_InitBootClocks();    BOARD_InitDebugConsole();    /* Set clock source for ADC0 */    CLOCK_SetClkDiv(kCLOCK_DivAdcAsyncClk, 2U, true);    CLOCK_AttachClk(kFRO_HF_to_ADC_CLK);    /* Disable LDOGPADC power down */    POWER_DisablePD(kPDRUNCFG_PD_LDOGPADC);    ANACTRL_Init(ANACTRL);    ANACTRL_EnableVref1V(ANACTRL, true);    PRINTF("LPADC DMA Example\r\n");    PRINTF("ADC CLK:%d\r\n", CLOCK_GetAdcClkFreq());    PRINTF("CORE CLK:%d\r\n", CLOCK_GetCoreSysClkFreq());        /* Configure peripherals. */    DMA_Configuration();    ADC_Configuration();    PRINTF("ADC Full Range: %d\r\n", g_LpadcFullRange);    PRINTF("ADCResolution: %dbit\r\n", (g_LpadcCommandConfigStruct.conversionResolutionMode == kLPADC_ConversionResolutionStandard)?(12):(16));            SysTick_Config(0xFFFFFF);    int tick;    PRINTF("Please press any key to trigger the conversion.\r\n");    while (1)    {        /* Get the input from terminal and trigger the converter by software. */        GETCHAR();        g_DmaTransferDoneFlag = false;                LPADC_DoSoftwareTrigger(DEMO_LPADC_BASE, 1UL); /* Trigger the ADC and start the conversion. */        DMA_StartTransfer(&g_DmaHandleStruct); /* Enable the DMA every time for each transfer. */                tick = SysTick->VAL;        /* Wait for the converter & transfer to be done. */        while (false == g_DmaTransferDoneFlag) {};        tick = tick - SysTick->VAL;        tick = tick / (CLOCK_GetCoreSysClkFreq() / (1000*1000));        printf("%-16s%dus(%.3fMS/s)\r\n",     "TIME:",      tick, (1 / (float)tick)*ADC_DMA_SIZE);                int i;        adc_sum = 0;        adc_sum_sqrt = 0;        for(i=0; i<ADC_DMA_SIZE; i++)        {            adc_result[i] = ((uint16_t)(adc_result[i] & ADC_RESFIFO_D_MASK) >> g_LpadcResultShift);            adc_sum += (float)adc_result[i];            adc_sum_sqrt += (adc_result[i]*adc_result[i]);                       // PRINTF("ADC[%d]:%d\r\n", i, adc_result[i]);        }               // printf("SUM:%.2f\r\n", adc_sum);      //  printf("SSUM:%.2f\r\n", adc_sum_sqrt);        adc_mean = adc_sum / ADC_DMA_SIZE;        adc_std  = (adc_sum_sqrt -  PF(adc_sum)/ADC_DMA_SIZE) / (ADC_DMA_SIZE-1);        adc_std  = sqrt(adc_std);                printf("%-16s%f\r\n",     "AVG :",      adc_mean);        printf("%-16s%f\r\n",     "STD :",      adc_std);    } } static void ADC_Configuration(void) {    lpadc_config_t lpadcConfigStruct;    lpadc_conv_trigger_config_t lpadcTriggerConfigStruct;    /* Configure ADC. */    LPADC_GetDefaultConfig(&lpadcConfigStruct);    lpadcConfigStruct.enableAnalogPreliminary = true;    lpadcConfigStruct.conversionAverageMode = kLPADC_ConversionAverage1;    lpadcConfigStruct.powerLevelMode=kLPADC_PowerLevelAlt4;    lpadcConfigStruct.referenceVoltageSource = DEMO_LPADC_VREF_SOURCE;    lpadcConfigStruct.FIFO0Watermark = 2;    LPADC_Init(DEMO_LPADC_BASE, &lpadcConfigStruct);    LPADC_DoOffsetCalibration(DEMO_LPADC_BASE);    LPADC_DoAutoCalibration(DEMO_LPADC_BASE);    /* Set conversion CMD configuration. */    LPADC_GetDefaultConvCommandConfig(&g_LpadcCommandConfigStruct);    g_LpadcCommandConfigStruct.channelNumber = DEMO_LPADC_USER_CHANNEL;    g_LpadcCommandConfigStruct.sampleTimeMode = kLPADC_SampleTimeADCK3;    g_LpadcCommandConfigStruct.loopCount = 1;    g_LpadcCommandConfigStruct.conversionResolutionMode = kLPADC_ConversionResolutionHigh;  //  g_LpadcCommandConfigStruct.conversionResolutionMode = kLPADC_ConversionResolutionStandard;        g_LpadcCommandConfigStruct.chainedNextCommandNumber = DEMO_LPADC_USER_CMDID;    LPADC_SetConvCommandConfig(DEMO_LPADC_BASE, DEMO_LPADC_USER_CMDID, &g_LpadcCommandConfigStruct);    /* Set trigger configuration. */    LPADC_GetDefaultConvTriggerConfig(&lpadcTriggerConfigStruct);    lpadcTriggerConfigStruct.targetCommandId       = DEMO_LPADC_USER_CMDID;    lpadcTriggerConfigStruct.enableHardwareTrigger = true;    LPADC_SetConvTriggerConfig(DEMO_LPADC_BASE, 0U, &lpadcTriggerConfigStruct); /* Configurate the trigger0. */    /* DMA request enabled. */    LPADC_EnableFIFO0WatermarkDMA(DEMO_LPADC_BASE, true); } static void DMA_Configuration(void) {    dma_channel_config_t dmaChannelConfigStruct; #if defined(DEMO_DMA_HARDWARE_TRIGGER) && DEMO_DMA_HARDWARE_TRIGGER    /* Configure INPUTMUX. */    INPUTMUX_Init(DEMO_INPUTMUX_BASE);    INPUTMUX_AttachSignal(DEMO_INPUTMUX_BASE, DEMO_DMA_ADC_CHANNEL, DEMO_DMA_ADC_CONNECTION); #endif /* DEMO_DMA_HARDWARE_TRIGGER */    /* Configure DMA. */    DMA_Init(DEMO_DMA_BASE);    DMA_EnableChannel(DEMO_DMA_BASE, DEMO_DMA_ADC_CHANNEL);    DMA_CreateHandle(&g_DmaHandleStruct, DEMO_DMA_BASE, DEMO_DMA_ADC_CHANNEL);    DMA_SetCallback(&g_DmaHandleStruct, DEMO_DMA_Callback, NULL);    /* Prepare and submit the transfer. */    DMA_PrepareChannelTransfer(&dmaChannelConfigStruct,              /* DMA channel transfer configuration structure. */                               (void *)DEMO_LPADC_RESFIFO_REG_ADDR,  /* DMA transfer source address. */                               (void *)adc_result,              /* DMA transfer destination address. */                               g_XferConfig,                         /* Xfer configuration */                               kDMA_PeripheralToMemory,               /* DMA transfer type. */                               NULL,                                 /* DMA channel trigger configurations. */                               (dma_descriptor_t *)&(s_dma_table[0]) /* Address of next descriptor. */    );    DMA_SubmitChannelTransfer(&g_DmaHandleStruct, &dmaChannelConfigStruct);    /* Set two DMA descripters to use ping-pong mode.  */    DMA_SetupDescriptor((dma_descriptor_t *)&(s_dma_table[0]), g_XferConfig, (void *)DEMO_LPADC_RESFIFO_REG_ADDR, (void *)adc_result, (dma_descriptor_t *)&(s_dma_table[4]));    DMA_SetupDescriptor((dma_descriptor_t *)&(s_dma_table[4]), g_XferConfig, (void *)DEMO_LPADC_RESFIFO_REG_ADDR, (void *)adc_result, (dma_descriptor_t *)&(s_dma_table[0])); } void SysTick_Handler(void) { }

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