Hello,
I am working on a college project and struggle with sending a message to the virtual terminal using USART interrupt.
I work with following code:
void UART_Send (uint8_t *buffer){
USART1->CR1 |= USART_CR1_TXEIE; // Enable TXE Interrupt
USART1->DR = buffer[0]; // Send data
}
void USART1_IRQHandler(void) {
// Check TXE flag
int Tx1_Counter=0;
if(USART1->SR & USART_SR_TXE) {
Tx1_Counter++;
if(Tx1_Counter <= strLength(buffer) - 1)
{
USART1->DR = buffer[Tx1_Counter] & 0xFF;
} else
{
}
// Transmission completes
Tx1_Counter = 0;
// Clear the counter
// Disable TXE interrupt
USART1->CR1 &= ~USART_CR1_TXEIE;
}
}
I set up whole init using registers which currently looks like this:
#include <stdio.h>
#include "stm32f103x6.h"
#include "util.h"
void USART_Init (USART_TypeDef * USARTx) {
// Default setting:
// No hardware flow control, 8 data bits, no parity, 1 start bit and 1 stop bit
USARTx->CR1 &= ~USART_CR1_UE; // Disable USART
// Configure word length to 8 bit
USARTx->CR1 &= ~USART_CR1_M; // M: 00 = 8 data bits, 01 = 9 data bits, 10 = 7 data bits
USARTx->CR1 |= (01 << USART_CR1_M_Pos);
// Configure oversampling mode: Oversampling by 16
// CORTEX M4 samo - USARTx->CR1 &= ~USART_CR1_OVER8; // 0 = oversampling by 16, 1 = oversampling by 8
// Configure stop bits to 1 stop bit
// 00: 1 Stop bit; 01: 0.5 Stop bit
// 10: 2 Stop bits; 11: 1.5 Stop bit
USARTx->CR2 &= ~USART_CR2_STOP;
// Podesavanje Baudrate - Strana 798 i 799, 27.3.4 Fractional baud rate generation, Tabela 192. na strani 799
// CSet Baudrate to 9600 using APB frequency
// Tx/Rx baud = f_CK / (16*USARTDIV),
// BRR = 0x1D4C za USARTDIV=468,75 za 72MHz, odnosno BRR = 0xEA6, USARTDIV = 234,75 za 36MHZ, Limited to 16 bits
// Default clock je 8MHz, USARTDIV = 8.000.000/(16*9600) = 52,083 ,
// DIV_Mantissa = 52 = 0x34, DIV_Fraction=0,083 u hex broju = 0,083*16=1,328->DIV_Fraction=0x1
// -> BRR = 0x341
USARTx->BRR = 0x341;
USARTx->CR1 |= (USART_CR1_RE | USART_CR1_TE); // Transmitter and Receiver enable
USARTx->CR1 |= USART_CR1_UE; // USART enable
}
void UART1_GPIO_Init(void) {
// Enable the peripheral clock of GPIO Port A
RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
// ********************** USART 1 ***************************
// U Reference Manualu STM32F103R6 treba videti na koje pinove GPIO porta se mapira USART1 i u kojem rezimu treba setovati te pinove GPIO porta
// jer se ukljucuje alternativna funkcija
// PA9 = USART1_TX, PA10 = USART1_RX (strana 181)
// Rezim rada GPIO Porta - strana 166 i 167
// USARTx_TX - Ako radi u Full duplex rezimu podesiti: Alternate function push-pull (The USART_TX pin can also be configured as alternate function open drain.)
// USARTx_TX - Ako radi u Half duplex synchronous rezimu podesiti: Alternate function push-pull
// USARTx_RX - Ako radi u Full duplex rezimu, podesiti port kao: Input floating / Input pull-up
// USARTx_RX - Ako radi u Half duplex synchronous rezimu, onda se ne koristi pin: Not used. Can be used as a general IO
// Prvo podesavamo pin PA9 na koji se povezuje USART1_TX, tako da pin treba da radi u izlaznom rezimu sa alternativnom funkcijom
GPIOA->CRH &= ~(GPIO_CRH_MODE9 | GPIO_CRH_CNF9); // Obrisati CNF9[1:0] i MODE9[1:0] - za konfiguraciju 9 pina, porta A
// Alternativno moze da se koristi GPIOA_CRH &= ~(0xF << 4);
// Ili GPIOA_CRH &= ~0xF0;
// Prvo se podesava rezim rada pina 9 porta A - ulazni, ili jedan od tri izlazna.
// Vrednosti za MODE[1:0]: 00: Input mode (reset state), 01: Output mode, max speed 10 MHz.
// 10: Output mode, max speed 2 MHz, 11: Output mode, max speed 50 MHz.
GPIOA->CRH |= (GPIO_CRH_MODE9_1 | GPIO_CRH_MODE9_0);// Setujemo vrednost 11 za Mode9[1:0] = Output mode, max speed 50 MHz.
// isto moze i GPIO->CRH |= 0b11 << 4; ili GPIO->CRH |= 0x30;
// Sada se podesava kako da pin radi u izlaznom rezimu.
// Vrednosti za GPIOx_CNF[1:0]: Ako polje MODE[1:0] nije = 00, odnosno pin je setovan u nekom od izlaznih rezima, onda:
// 00: General purpose output push-pull, 01: General purpose output Open-drain
// 10: Alternate function output Push-pull, 11: Alternate function output Open-drain
GPIOA->CRH |= GPIO_CRH_CNF9_1; // Setuje se vrednost 10 za Mode9[1:0] -> Alternate function push-pull
// Moze i GPIO->CRH |= 0x80;
// Zatim podesavamo pin PA10 na koji se povezuje USART1_RX, tako da pin treba da radi u ulaznom rezimu sa alternativnom funkcijom
GPIOA->CRH &= ~(GPIO_CRH_MODE10 | GPIO_CRH_CNF10); // Obrisati CNF9[1:0] i MODE9[1:0] - za konfiguraciju 10 pina, porta A
// Prvo podesavamo rezim rada pina 10, porta A
// Vrednosti za MODE[1:0]: 00: Input mode (reset state), 01: Output mode, max speed 10 MHz. 10: Output mode, max speed 2 MHz, 11: Output mode, max speed 50 MHz.
// Mi hocemo da postavimo vrednost 00: Input mode, ali posto smo prethodno obrisali te bitove, ne diramo nista
// Vrednosti za GPIOx_CNF[1:0]: Ako je polje MODE[1:0] = 00, odnosno pin je u input rezimu, onda:
// 00: Analog mode, 01: Floating input (reset state), 10: Input with pull-up / pull-down, 11: Reserved
GPIOA->CRH |= GPIO_CRH_CNF10_0; // USART radi u full-duplex rezimu, pa setujemo kao Floating input = 01, videti gore ili strana 167
}
void UART1_Init(void) {
// Enable the clock of USART 1
RCC->APB2ENR |= RCC_APB2ENR_USART1EN; // Enable USART 1 clock
UART1_GPIO_Init();
USART_Init(USART1);
//NVIC_SetPriority(USART1_IRQn, 0); // Set Priority to 1
//NVIC_EnableIRQ(USART1_IRQn); // Enable interrupt of USART1 peripheral
}
Sorry if Serbian comments make the code hard to read.
The whole project is done in Proteus 8.12 and Eclipse. I am working with STM32F103R6.
The main problem is how to call the interrupt and how to pass buffer in the interrupt handler.
Any help would be much appreciated!
