STM32F4 getting values from buffer

[fiulala]

Posted on July 01, 2015 at 18:07

Hi, I wanted to personalize this code I found to fill half a buffer and then process the data while the second half of the buffer continues to fill. To understand how this works I modified the code so it turns on a LED if the first value stored in the buffer is higher than 2500 mV. I think I don't know how to get data from the buffer... Need help.

Here is the code:

// STM32 ADC Sample @ 200 KHz (PC.1) STM32F4 Discovery - sourcer32@gmail.com
// Assumptions per system_stm32f4xx.c CPU @ 168 MHz, APB2 @ 84 MHz (/2), APB1 @ 42 MHz (/4)
#include ''stm32f4xx.h''
#include ''stm32f4xx_rcc.h''
#include ''stm32f4xx_gpio.h''
#include ''stm32f4xx_adc.h''
#include ''stm32f4xx_dma.h''
#include ''stm32f4_discovery.h''
#include ''stm32f4xx_tim.h''
/**************************************************************************************/
void RCC_Configuration(void)
{
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
}
/**************************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* ADC Channel 11 -> PC1
*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOC, &GPIO_InitStructure);
}
/**************************************************************************************/
void ADC_Configuration(void)
{
ADC_CommonInitTypeDef ADC_CommonInitStructure;
ADC_InitTypeDef ADC_InitStructure;
/* ADC Common Init */
ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div2;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&ADC_CommonInitStructure);
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = DISABLE; // 1 Channel
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; // Conversions Triggered
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T2_TRGO;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion = 1;
ADC_Init(ADC1, &ADC_InitStructure);
/* ADC1 regular channel 11 configuration */
ADC_RegularChannelConfig(ADC1, ADC_Channel_11, 1, ADC_SampleTime_15Cycles); // PC1
/* Enable DMA request after last transfer (Single-ADC mode) */
ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);
/* Enable ADC1 DMA */
ADC_DMACmd(ADC1, ENABLE);
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
}
/**************************************************************************************/
#define BUFFERSIZE 400 // 200KHz x2 HT/TC at 1KHz
__IO uint16_t ADCConvertedValues[BUFFERSIZE];
static void DMA_Configuration(void)
{
DMA_InitTypeDef DMA_InitStructure;
DMA_InitStructure.DMA_Channel = DMA_Channel_0;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&ADCConvertedValues[0];
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = BUFFERSIZE; // Count of 16-bit words
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Enable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream0, &DMA_InitStructure);
/* Enable DMA Stream Half / Transfer Complete interrupt */
DMA_ITConfig(DMA2_Stream0, DMA_IT_TC | DMA_IT_HT, ENABLE);
/* DMA2_Stream0 enable */
DMA_Cmd(DMA2_Stream0, ENABLE);
}
/**************************************************************************************/
void TIM2_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
/* Time base configuration */
TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
TIM_TimeBaseStructure.TIM_Period = (84000000 / 200000) - 1; // 200 KHz, from 84 MHz TIM2CLK (ie APB1 = HCLK/4, TIM2CLK = HCLK/2)
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
/* TIM2 TRGO selection */
TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update); // ADC_ExternalTrigConv_T2_TRGO
/* TIM2 enable counter */
TIM_Cmd(TIM2, ENABLE);
}
/**************************************************************************************/
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
/* Enable the DMA Stream IRQ Channel */
NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
/**************************************************************************************/
void DMA2_Stream0_IRQHandler(void) // Called at 1 KHz for 200 KHz sample rate, LED Toggles at 500 Hz
{
/* Test on DMA Stream Half Transfer interrupt */
if(DMA_GetITStatus(DMA2_Stream0, DMA_IT_HTIF0))
{
/* Clear DMA Stream Half Transfer interrupt pending bit */
DMA_ClearITPendingBit(DMA2_Stream0, DMA_IT_HTIF0);
/* Turn LED3 off: Half Transfer */
STM_EVAL_LEDOff(LED3);
// Add code here to process first half of buffer (ping)
int a;
double valueinmV;
a=ADCConvertedValues[0];
valueinmV = (a*3300)/4095;
if(valueinmV>2500)
{
STM_EVAL_LEDOn(LED5);
}
else
{
STM_EVAL_LEDOff(LED5);
}
}
/* Test on DMA Stream Transfer Complete interrupt */
if(DMA_GetITStatus(DMA2_Stream0, DMA_IT_TCIF0))
{
/* Clear DMA Stream Transfer Complete interrupt pending bit */
DMA_ClearITPendingBit(DMA2_Stream0, DMA_IT_TCIF0);
/* Turn LED3 on: End of Transfer */
STM_EVAL_LEDOn(LED3);
// Add code here to process second half of buffer (pong)
}
}
void ClockSetUp(void) {
/* Initialize system */
SystemInit();
RCC_DeInit();
/* PLL Setup */
RCC_HSEConfig(RCC_HSE_ON);
RCC_WaitForHSEStartUp();
RCC_PLLConfig(RCC_PLLSource_HSE,5,210,2,4);
RCC_PLLCmd(ENABLE);
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) != SET);
RCC_HCLKConfig(RCC_SYSCLK_Div1);
RCC_PCLK1Config(RCC_HCLK_Div4);
RCC_PCLK2Config(RCC_HCLK_Div2);
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
}
/**************************************************************************************/
int main(void)
{
RCC_Configuration();
GPIO_Configuration();
NVIC_Configuration();
TIM2_Configuration();
DMA_Configuration();
ADC_Configuration();
ClockSetUp();
STM_EVAL_LEDInit(LED3); /* Configure LEDs to monitor program status */
STM_EVAL_LEDInit(LED4);
STM_EVAL_LEDOn(LED3); /* Turn LED3 on, 500 Hz means it working */
/* Start ADC1 Software Conversion */
ADC_SoftwareStartConv(ADC1);
while(1){
}
}

#stm32f4-dma

[Tesla DeLorean]

Posted on July 01, 2015 at 19:35

I think I don't know how to get data from the buffer... Need help.

Get it where, it's just a standard C array full of data. You need to figure out where you want to sink/process it, at the rate it's being generated.The first half of the array, elements [0..199] will be available at the HT interrupt, and then [200..399] at the TC interrupt.The DISCO boards have a 3.0V reference, not a 3.3V one.

[Tesla DeLorean]

Posted on July 01, 2015 at 19:37

Are you using CooCox?

I'd do the ClockSetUp(); very early in main(), if your tool chain is not calling SystemInit() properly prior to entering.