STM32F103ZE USART baud rate over 115200

Question

Posted on July 29, 2011 at 14:10Hi,  I have a little problem with setting a custom speed on the STM32 above 115200th The problem occurs both when using the init or manual configuration (manual calculation of values ??for the registry BRR). There is no problem with different transmissions 9600, 28800 until 115200th After this value, the terminal is silent. Only by using the library function to initialize the USART to the terminal reached some wrong information. With manual configuration did not reach above the 115200th Overall, I must dispel USART to 1Mb, because I make the servo controller which is at such a speed that communicates with the interface.  I would add that I am using win 7 and the terminal v1.9b. Once I tested the speed, eg 256 000 for ATMega32 and worked without a problem.  &sharpinclude ''stm32f10x.h''&sharpinclude ''stm32f10x_conf.h'' void RCC_Conf(void); int main(){ RCC_Conf();uint16_t zmienna =0;  USART_InitTypeDef USART_InitStructure; GPIO_InitTypeDef GPIO_InitStructure;  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE); /* Configure USART1 Tx (PA.09) as alternate function push-pull */ GPIO_InitStructure.GPIO_Pin= GPIO_Pin_9; GPIO_InitStructure.GPIO_Mode= GPIO_Mode_AF_PP; GPIO_InitStructure.GPIO_Speed= GPIO_Speed_50MHz; GPIO_Init(GPIOA, &GPIO_InitStructure); /* Configure USART1 Rx (PA.10) as input floating */ GPIO_InitStructure.GPIO_Pin= GPIO_Pin_10; GPIO_InitStructure.GPIO_Mode= GPIO_Mode_IN_FLOATING; GPIO_Init(GPIOA, &GPIO_InitStructure);    USART_ClockInitTypeDef USART_ClockInitStructure;  USART_ClockInitStructure.USART_Clock= USART_Clock_Disable; USART_ClockInitStructure.USART_CPOL= USART_CPOL_Low; USART_ClockInitStructure.USART_CPHA= USART_CPHA_2Edge; USART_ClockInitStructure.USART_LastBit= USART_LastBit_Disable;  USART_ClockInit(USART1, &USART_ClockInitStructure);   USART_InitStructure.USART_WordLength= USART_WordLength_8b; USART_InitStructure.USART_StopBits= USART_StopBits_1; USART_InitStructure.USART_Parity= USART_Parity_No ; USART_InitStructure.USART_HardwareFlowControl= USART_HardwareFlowControl_None; USART_InitStructure.USART_Mode= USART_Mode_Rx | USART_Mode_Tx; uint32_t tmp;  tmp = USART1->CR1; tmp |= USART_InitStructure.USART_WordLength|USART_InitStructure.USART_Parity|USART_InitStructure.USART_Mode; USART1->CR1 = tmp;  tmp = USART1->CR2; tmp |= USART_InitStructure.USART_StopBits; USART1->CR2 = tmp;  tmp = USART1->CR3; tmp |= USART_InitStructure.USART_HardwareFlowControl; USART1->CR3 = tmp;  USART1->BRR =(uint16_t)0x9c4; /* Enable USART1 */ USART_Cmd(USART1, ENABLE); while(1){while(USART_GetFlagStatus(USART1, USART_FLAG_TXE)== RESET){} USART_SendData(USART1, 0xA2);while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE)== RESET){} zmienna = USART_ReceiveData(USART1);} return0;} void RCC_Conf(void){ ErrorStatus HSEStartStatus; //reset ustawie? RCC RCC_DeInit(); //W??cz HSE RCC_HSEConfig(RCC_HSE_ON); //Czekaj a? HSE b?dzie gotowy HSEStartStatus = RCC_WaitForHSEStartUp(); if(HSEStartStatus == SUCCESS){ FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable); //zwloka dla pamieci Flash FLASH_SetLatency(FLASH_Latency_2); //HCLK = SYSCLK RCC_HCLKConfig(RCC_SYSCLK_Div1); //PCLK2 = HCLK RCC_PCLK2Config(RCC_HCLK_Div1); //PCLK1 = HCLK/2 RCC_PCLK1Config(RCC_HCLK_Div2); //PLLCLK = 8MHz * 9 = 72MHz RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9); //W??cz PLL RCC_PLLCmd(ENABLE); //Czekaj a? PLL poprawnie si? uruchomiwhile(RCC_GetFlagStatus(RCC_FLAG_PLLRDY)== RESET){} //PLL b?dzie zrodlem sygnalu zegarowego RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK); while(RCC_GetSYSCLKSource()!=0x08){}}   } #stm32-usart

Tesla DeLorean · Answer

Posted on July 29, 2011 at 17:56The 24 MHz VL Discovery has NO problem outputting at 460800 baud into a USB-to-CMOS Serial dongle. a) Check your serial port supports the rate. Most internal/motherboard ones don't. b) Attach a scope and verify the bit/baud clocking is what you expect. c) RS232 driver chips often filter >1Mbaud. void RCC_Configuration(void); void GPIO_Configuration(void); void USART_Configuration(void); void RCC_Configuration(void) {     ErrorStatus HSEStartUpStatus;   /* Enable HSE */   RCC_HSEConfig(RCC_HSE_ON);   /* Wait till HSE is ready */   HSEStartUpStatus = RCC_WaitForHSEStartUp();   if (HSEStartUpStatus == SUCCESS)   { #if 0 // VL Does not require     /* Enable Prefetch Buffer */     FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);     /* Flash 0 wait state */     FLASH_SetLatency(FLASH_Latency_0); #endif     /* HCLK = SYSCLK */     RCC_HCLKConfig(RCC_SYSCLK_Div1);     /* PCLK2 = HCLK */     RCC_PCLK2Config(RCC_HCLK_Div1);     /* PCLK1 = HCLK */     RCC_PCLK1Config(RCC_HCLK_Div1);     /* ADCCLK = PCLK2/4 */     RCC_ADCCLKConfig(RCC_PCLK2_Div4);     /* PLLCLK = 8MHz * 3 = 24 MHz */     RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_3);     /* Enable PLL */     RCC_PLLCmd(ENABLE);     /* Wait till PLL is ready */     while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);     /* Select PLL as system clock source */     RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);     /* Wait till PLL is used as system clock source */     while(RCC_GetSYSCLKSource() != 0x08);     } } void USART_Configuration(void) {     GPIO_InitTypeDef GPIO_InitStructure;   USART_InitTypeDef USART_InitStructure;   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);   /* Configure USART Tx as alternate function push-pull */   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;  // PA.09 USART1.TX   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   GPIO_Init(GPIOA, &GPIO_InitStructure);   /* Configure USART Rx as input floating */   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; // PA.10 USART1.RX   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;   GPIO_Init(GPIOA, &GPIO_InitStructure);   /* USART resources configuration (Clock, GPIO pins and USART registers) ----*/   /* USART configured as follow:         - BaudRate = 460800 baud         - Word Length = 8 Bits         - One Stop Bit         - No parity         - Hardware flow control disabled (RTS and CTS signals)         - Receive and transmit enabled   */   USART_InitStructure.USART_BaudRate = 460800;   USART_InitStructure.USART_WordLength = USART_WordLength_8b;   USART_InitStructure.USART_StopBits = USART_StopBits_1;   USART_InitStructure.USART_Parity = USART_Parity_No;   USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;   USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;   /* Enable UART clock */   RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);   /* USART configuration */   USART_Init(USART1, &USART_InitStructure);   /* Enable the USART1 */   USART_Cmd(USART1, ENABLE); } int main(void) {     char str[] = ''Welcome to wherever you are...'';     char *s;   RCC_Configuration();   USART_Configuration();   /* Infinite loop */     while(1)     {         s = str;         while(*s)       {         while((USART1->SR & 0x40)==0);         USART1->DR = *s++;       }     }   /* does not exit - kind of important */   return(1); }

Sign up

Login with SSO

Login to the community

Login with SSO

Scanning file for viruses.

This file cannot be downloaded