STM32F3 ADC uses DMA mode to transfer conversion data

This article uses ADC to convert the voltage value output by the potentiometer, and uses DMA mode to transmit the conversion result. The average value is taken every 8 sampling conversions to perform a simple digital filter.

Detailed configuration and use of ADC

See the previous diary on the use of ADC in STM32 , just add a step to configure DMA at the end:

DMA for ADC channels features configuration
 To enable the DMA mode for ADC channels group, use the ADC_DMACmd() function.
 To configure the DMA transfer request, use ADC_DMAConfig() function.

DMA Configuration

(摘自STM32F3官方用户手册UM1581 User manual)
1. Enable The DMA controller clock using
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE) function for DMA1 or using RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2, ENABLE) function for DMA2.
2. Enable and configure the peripheral to be connected to the DMA channel (except for internal SRAM / FLASH memories: no initialization is necessary).
3. For a given Channel, program the Source and Destination addresses, the transfer Direction, the Buffer Size, the Peripheral and Memory Incrementation mode and Data
Size, the Circular or Normal mode, the channel transfer Priority and the Memory-to-Memory transfer mode (if needed) using the DMA_Init() function.
4. Enable the NVIC and the corresponding interrupt(s) using the function
DMA_ITConfig() if you need to use DMA interrupts.
5. Enable the DMA channel using the DMA_Cmd() function.
6. Activate the needed channel Request using PPP_DMACmd() function for any PPP peripheral except internal SRAM and FLASH (ie. SPI, USART ...) The function allowing this operation is provided in each PPP peripheral driver (ie. SPI_DMACmd for SPI peripheral).
7. Optionally, you can configure the number of data to be transferred when the channel
is disabled (ie. after each Transfer Complete event or when a Transfer Error occurs) using the function DMA_SetCurrDataCounter(). And you can get the number of remaining data to be transferred using the function DMA_GetCurrDataCounter() at run time (when the DMA channel is enabled and running).
8. To control DMA events you can use one of the following two methods:
a. Check on DMA channel flags using the function DMA_GetFlagStatus().
b. Use DMA interrupts through the function DMA_ITConfig() at initialization phase and DMA_GetITStatus() function into interrupt routines in communication phase. After checking on a flag you should clear it using DMA_ClearFlag() function. And after checking on an interrupt event you should clear it using DMA_ClearITPendingBit()function.

Important code:

1. #include "ADC_DMA.h"  

2.   

3. #define DATANUM 8  

4. uint8_t FLAG = 0; //Conversion times flag  

5. uint16_t CONV_RESULTS[DATANUM];  

6. void ADC_Config(void)  

7. {  

8.     ADC_InitTypeDef       ADC_InitStructure;  

9.     ADC_CommonInitTypeDef ADC_CommonInitStructure;  

10.       

11.     RCC_ADCCLKConfig(RCC_ADC12PLLCLK_Div2);  

12.     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_ADC12,ENABLE);  

13.       

14.     //GPIO_Config(); //Configure the sampling input pin to analog input mode  

15.   

16.     //......other  

17.     ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_2;  

18.     ADC_CommonInitStructure.ADC_DMAMode = ADC_DMAMode_Circular;  

19.     //.......other  

20.     ADC_CommonInit(USING_ADC,&ADC_CommonInitStructure);  

21.   

22.     //ADC Init,ADC_Init(USING_ADC,&ADC_InitStructure);  

23.       

24.     ADC_ITConfig(USING_ADC, ADC_IT_EOC, ENABLE); //Enable interrupt  

25.   

26.     ADC_DMAConfig(USING_ADC, ADC_DMAMode_Circular); //Configure ADC_DMA, very important  

27.   

28.     ADC_DMACmd(USING_ADC, ENABLE);//打开ADC_DMA  

29.   

30.     DMA_Config();  

31.   

32.     ADC_Cmd(USING_ADC,ENABLE);  

33.   

34.     while(!ADC_GetFlagStatus(USING_ADC, ADC_FLAG_RDY));  

35.   

36.     ADC_StartConversion(USING_ADC);   

37.   

38. }  

39.   

40. void GPIO_Config(void)  

41. {  

42.     //.......  

43.     //......  

44. }  

45. void DMA_Config(void)  

46. {  

47.     DMA_InitTypeDef DMA_InitStructure;  

48.   

49.     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);  

50.   

51.     DMA_DeInit(DMA1_Channel1);  

52.       

53.     DMA_InitStructure.DMA_PeripheralBaseAddr = ADC_DATA_ADDR; //Address of ADC data register DR  

54.     DMA_InitStructure.DMA_MemoryBaseAddr = (u32)&CONV_RESULTS; //Address to store conversion results  

55.     DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;  

56.     DMA_InitStructure.DMA_BufferSize = DATANUM;  

57.     //.....  

58.       

59.     DMA_Init(DMA1_Channel1, &DMA_InitStructure);  

60.       

61.   

62.     DMA_Cmd(DMA1_Channel1, ENABLE);  

63.   

64. }  

65. void ADC1_2_IRQHandler (void)  

66. {  

67.   

68.     FLAG++; // Check FLAG in the main function and wake up the process  

69.             // Calculate the number of converted data  

70.     if(FLAG>DATANUM-1)  

71.                 {  

72.                     FLAG=0;  

73.                 }  

74.       

75.     ADC_ClearITPendingBit(USING_ADC, ADC_IT_EOC);  

76. }  

77.   

78. //Get the average value of the conversion result and do filtering  

79. uint16_t GetAverage(void)  

80. {  

81.     u8 i=0;  

82.     u16 average=0;  

83.     u32 sum=0,voltage=0;  

84.       

85.     for(i=0;i

86.         {  

87.             sum += CONV_RESULTS[i];  

88.         }  

89.       

90.     average = sum/data;  

91.     voltage = average*3300/0xFFF;  

92.   

93.     return voltage;  

94. }  

95. //Abort placement  

96. void NVIC_Config(void)  

97. {  

98.     NVIC_InitTypeDef NVIC_InitStruct;  

99.       

100.     NVIC_InitStruct.NVIC_IRQChannel =ADC1_IRQn;  

101.     //........  

102.       

103.     NVIC_Init(&NVIC_InitStruct);  

104. }  

Source code download:

http://download.csdn.net/detail/wind4study/8674381