STM32F303 ADC Sequence Conversion Problem

[MAbba.8]

Hello I am trying to use STM32F303VCT6 ADC1 to measure 4 channels in sequence. I am using TIMER 3 to trigger start of sequence conversion. I am using DMA1 to transfer data to an array. My code is as follows:

ADC Configuration:

ADC_InitTypeDef ADC_InitStructure;
ADC_CommonInitTypeDef ADC_CommonInitStructure;
 
/* Configure the ADC clock */
 RCC_ADCCLKConfig(RCC_ADC12PLLCLK_Div16);
 
 /* Enable ADC1 clock */
 RCC_AHBPeriphClockCmd(RCC_AHBPeriph_ADC12, ENABLE);
	
 ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent; 
 ADC_CommonInitStructure.ADC_Clock = ADC_Clock_AsynClkMode; 
 ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_1 ; 
 ADC_CommonInitStructure.ADC_DMAMode = ADC_DMAMode_Circular; 
 ADC_CommonInitStructure.ADC_TwoSamplingDelay = 0; 
 ADC_CommonInit(ADC1, &ADC_CommonInitStructure);
 
 ADC_InitStructure.ADC_ContinuousConvMode = ADC_ContinuousConvMode_Disable;
 ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b; 
 ADC_InitStructure.ADC_ExternalTrigConvEvent = ADC_ExternalTrigConvEvent_4; /*TIMER 
 3 Triggers ADC*/ 
 ADC_InitStructure.ADC_ExternalTrigEventEdge = ADC_ExternalTrigEventEdge_RisingEdge;
 ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
 ADC_InitStructure.ADC_OverrunMode = ADC_OverrunMode_Disable; 
 ADC_InitStructure.ADC_AutoInjMode = ADC_AutoInjec_Disable; 
 ADC_InitStructure.ADC_NbrOfRegChannel = 4;
 ADC_Init(ADC1, &ADC_InitStructure);
	
 /* ADC1 regular channel1 configuration */ 
 ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_1Cycles5);
 /* ADC1 regular channel2 configuration */ 
 ADC_RegularChannelConfig(ADC1, ADC_Channel_2, 2, ADC_SampleTime_1Cycles5);
 /* ADC1 regular channel3 configuration */ 
 ADC_RegularChannelConfig(ADC1, ADC_Channel_3, 3, ADC_SampleTime_1Cycles5);
 /* ADC1 regular channel4 configuration */ 
 ADC_RegularChannelConfig(ADC1, ADC_Channel_4, 4, ADC_SampleTime_1Cycles5);
	
 ADC_RegularChannelSequencerLengthConfig (ADC1, 4);
	
 /* Configure ADC Channels 1,2,3,4 as analog input */
 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
 GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
 GPIO_Init(GPIOA, &GPIO_InitStructure);
	
 /* Calibration procedure */ 
 ADC_VoltageRegulatorCmd(ADC1, ENABLE);
 
 /* Insert delay equal to 5 ms */
 Delay(5);
 
 ADC_SelectCalibrationMode(ADC1, ADC_CalibrationMode_Single);
 ADC_StartCalibration(ADC1);
	
 while(ADC_GetCalibrationStatus(ADC1) != RESET );
	
 ADC_DMAConfig(ADC1, ADC_DMAMode_Circular);
 ADC_DMACmd(ADC1, ENABLE);
 
 /* Enable ADC1 */
 ADC_Cmd(ADC1, ENABLE);

DMA1 Configuration:

 DMA_InitTypeDef DMA_InitStructure;
 RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
	
 DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
 DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&adc_values; /*Array to hold ADC 
 values*/
 DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
 DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
 DMA_InitStructure.DMA_Priority = DMA_Priority_High;
 DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
 DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
 DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
 DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
 DMA_InitStructure.DMA_BufferSize = 4; // in data unit
 DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;
 DMA_Init(DMA1_Channel1, &DMA_InitStructure);
 DMA_Cmd(DMA1_Channel1, ENABLE);

TIMER 3 Configuration:

 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
 
	
 /* TIM3 Periph clock enable */
 RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
 
 /* Time base configuration */
 TIM_TimeBaseStructInit(&TIM_TimeBaseStructure); 
 TIM_TimeBaseStructure.TIM_Period = 0x2328; 
 TIM_TimeBaseStructure.TIM_Prescaler = 0x0; 
 TIM_TimeBaseStructure.TIM_ClockDivision = 0x0; 
 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; 
 TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
 
 /* TIM3 TRGO selection */
 TIM_SelectOutputTrigger(TIM3, TIM_TRGOSource_Update);
	
 /* TIM3 enable counter */
 TIM_Cmd(TIM3, ENABLE);

In main I have used following code to start the ADC process:

 DMA_Config();
 ADC_Config();
 TIM_Config();
 
 /* wait for ADRDY */
 while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_RDY));
 /* Start ADC1 Software Conversion */
 ADC_StartConversion(ADC1);

The problem I am facing is that my code can only convert the channel which is highest in the sequence. For example, for the configuration given above, I am able to see correct conversion value only on channel 1 of ADC 1, because its rank is 1 in the sequence. I have tried changing the channels in the sequence to confirm that the channel with highest rank i.e. first channel in sequence gets converted. I have not enabled any interrupts.

Kindly see the code and tell me what I am missing.