Erratic USART behaviour using KEIL 5 Compiler

Hi All,

I have a project that currently has a blinky, 2 ADC channel on DMA circular which were successfully working .

I have now implemented the USART2 on IRQ on my STM32F302 Nucleo. The USART2 is running at 32Mhz and 9600 baud. I have set up the USARt to echo back what I send from the PC.

As soon as I tried to implement the UART I started having issues.

1 - The characters echoed are not what I sent from my PC. I have tried changing the compiler setting in Keil 5. I changed the optimizations settings on the C/C++ tab from Level 0 to default. This helped somewhat but I still get back some random characters.

Furthermore, when I set it to default I cannot debug properly as the debugger seems to get stuck at some lines.

2 - My blinky also stops working which is odd

/*---------------------------------------------------------------------------------------------------------------
 
12/5/2019
 
SysCroeClock = 64Mhz
 
Blinky
ADC scaninng 2 channels continously in DMA Mode 1.5 conversiion cycles at 64Mhz
UART2 with interrupt running on clock of 32MHz at 9600 baud
---------------------------------------------------------------------------------------------------------------*/
 
 
 
 
#include "stm32f302x8.h"
 //----------------- Gloobal Variables -------------------------------------------------------------------------
uint16_t ADC_Samples[2] = {0,0};
void Delay (uint32_t nTime);
uint16_t ADC1ConvertedValue = 0;
uint16_t ADC1ConvertedVoltage = 0;
int calibration_value = 0;
volatile uint32_t TimingDelay = 0;
int x =0;
int 	CoreClock = 0;
 
void SysTick_Handler(void)
{
 TimingDelay--;
}
void Delay (uint32_t nTime)
{
 TimingDelay = nTime;
 while (TimingDelay !=0);
}
 
int init ()
{
	
	//---------------------- RCC Clock Initalization ------------------------------------------------------------------
	
	RCC->CR = 0x1; //HSI on
	while((RCC->CR & RCC_CR_HSIRDY) != RCC_CR_HSIRDY); // Waiting for HSI to be ready
	RCC->CR &= ~RCC_CR_PLLON; // Disable PLL
	while((RCC->CR & RCC_CR_PLLRDY)== RCC_CR_PLLRDY); // Wait for pll to turn off
	RCC->CFGR = RCC_CFGR_PLLSRC_HSI_DIV2 | RCC_CFGR_PLLMUL16 | RCC_CFGR_HPRE_DIV1 | RCC_CFGR_PPRE1_DIV2; //PLLSCR = HSI/2 , PLLMUL = x16 (64Mhz),AHB prescaler not devided, APB1 Clock /2 = 32MHz (Max=32MHz)
	RCC->CR |= 0x01000000; // Turn on PLL on
	while((RCC->CR & RCC_CR_PLLRDY) != RCC_CR_PLLRDY); // Waiting for PLL to be ready
	FLASH->ACR |= FLASH_ACR_LATENCY_1; // Adjust flash speed for new frequency
	RCC->CFGR |= RCC_CFGR_SW_1; // Set PLL as system clock
	while((RCC->CFGR & RCC_CFGR_SWS_1) != RCC_CFGR_SWS_1); // Wait fpr pll to be used as syste, clock
	
	
	//---------------------- DMA Initialization -------------------------------------------------------------------
	
	RCC->AHBENR |= RCC_AHBENR_DMA1EN; // DMA1 Enabled 
	
	//---------------------- Blinky Initialization ----------------------------------------------------------------
	
	RCC->AHBENR |= (1<<18); //Enabling AHB GPIOB
	 
 GPIOB->MODER |= 0x00000010; // PB2 Output
	GPIOB->OSPEEDR |= 0x0; // Low speed output on all of port B
 GPIOB->PUPDR |= 0x30; // PB2 pull down
 
	
	//----------------------- Checking System Clock ---------------------------------------------------------------
 SystemCoreClockUpdate(); // Calculating new system clock
	CoreClock = SystemCoreClock; 
	
	while (CoreClock != 64000000) // Error Handling
	{
		GPIOB->BSRR = (1<<2) ;
	}
	
	//--------------------------- ADC Configuration ----------------------------------------------------------------
	// ADC running off sysclock at 64Mhz, with mininum cycles for conversion to ensure maximum speed
	
	
	ADC1_COMMON->CCR = 0x0; // Resetting CKMODE
	RCC->CFGR2 = RCC_CFGR2_ADC1PRES_DIV12; // ADC Prescaler /1 i.e. ADC Clock = 64Mhz
	RCC->AHBENR |= RCC_AHBENR_ADC1EN; // Enable ADC1 clock
 ADC1_COMMON->CCR = 0x0; // Resetting CKMODE
	GPIOB->MODER |=	0x0000000F; // GPIOB PB1 set to Analog Mode ADC1_IN12, ADC1_IN11
	
 // Calibration procedure 
 ADC1->CR &= ~ADC_CR_ADVREGEN;
 ADC1->CR |= ADC_CR_ADVREGEN_0; // ADC Voltage regulator enabled
 for(x=0;x<500;x++); // Delay for ADC to stabilize
	
 ADC1->CR &= ~ADC_CR_ADCALDIF; // calibration in Single-ended inputs Mode.
 ADC1->CR |= ADC_CR_ADCAL; // Start ADC calibration
 // Read at 1 means that a calibration in progress.
 while (ADC1->CR == (ADC1->CR & ADC_CR_ADCAL)); // wait until calibration done
	calibration_value = ADC1->CALFACT; // Get Calibration Value ADC1
 
 
 ADC1->CR |= ADC_CR_ADEN; // Enable ADC1
 while(!ADC1->ISR & ADC_ISR_ADRD); // wait for ADRDY
	
 ADC1->SQR1 = 0xB301; // Channel 12 first, Channel 11 second, two in sequence 
	ADC1->SMPR2 = 0x0; // Channel 11 and 12 Minimum conversion time
	ADC1->CFGR = ADC_CFGR_DMAEN | ADC_CFGR_DMACFG | ADC_CFGR_CONT; // ADC DMA Enableed and set to circular mode and ADC in continous mode
	
	DMA1_Channel1->CPAR = (uint32_t)(&(ADC1->DR)); // Passing the pheripheral address of the data register into DMA Channel 1 
 DMA1_Channel1->CMAR = (uint32_t)ADC_Samples; // Passing the address of the arry to store the data in 
	DMA1_Channel1->CNDTR = 2; // " sets of data being passed
	DMA1_Channel1->CCR |= DMA_CCR_CIRC | DMA_CCR_MINC | DMA_CCR_PSIZE_0 | DMA_CCR_MSIZE_0; // Channel 1 Circular Mode, Memory Increment , P size = 16bit, M size = 16 bit
	DMA1_Channel1->CCR |= DMA_CCR_EN; // Enabling DMA
	
 ADC1->CR |= ADC_CR_ADSTART; // Start ADC1 Software Conversion 
	
	
	//------------------------------------ UART Enable -------------------------------------
	
	RCC->APB1ENR |= RCC_APB1ENR_USART2EN; // Enabling USART2 Clock
	RCC->AHBENR |= RCC_AHBENR_GPIOAEN; // Enabling Port A
	
	GPIOA->MODER |= GPIO_MODER_MODER2_1 | GPIO_MODER_MODER3_1; // Setting P24, PA3 as alternate function mode
	GPIOA->AFR[0] = 0x7700; // Alternate Functions USART 2 For PA2, PA3
 
	
 
	USART2->BRR = 0xD05; // 32MHz / 9600
	USART2->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_RXNEIE | USART_CR1_TXEIE; // Transmit Enable, Revive Enable, RX not empty Int Enable, TX not empty Int Enable
	USART2->CR1 |= USART_CR1_UE; // Uart Enable 
	
	NVIC_EnableIRQ(USART2_IRQn); // Enabling USART2 interrupt
	
	return(0);
	
}
int main()
{
 
	init();
 
	while (1)
	{
		
		GPIOB->BSRR = (1<<2) ;
		for ( x = 0; x<5000; x++)
		{
		}
		GPIOB->BSRR = (1<<(2+16));
		for ( x = 0; x<5000; x++)
		{
		}
	
	
}
}
 
	
void USART2_IRQHandler(void)
{
		if (USART2->ISR & USART_ISR_RXNE)
		{
			char temp = USART2->RDR;
			USART2->TDR = temp;
			while(!(USART2->ISR & USART_ISR_TC));
		}
		
		if (USART2->ISR & USART_ISR_TXE)
		{
		
		}
			
}

Do you guys have any ideas on might have cause this?

Thanks,

Glenn