Differences

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--- stm32:peripherals:usart [2016/03/03 12:14] – created feur
+++ stm32:peripherals:usart [2022/12/28 08:39] (current) – ruan
@@ Line 1: / Line 1: @@
-====== Universal (Synchronous/Asynchronous) Receiver Transmitter ======
+====== Universal Asynchronous Receiver Transmitter ======
-The USART offers a very flexible, full-duplex, industrial standard, serial receiver / transmitter. \\
+The UART offers a very flexible, full-duplex, industrial standard, serial receiver / transmitter. \\
 Including IrDA and modem operations (CTS/RTS). \\
@@ Line 13: / Line 13: @@
   * DMA and interrupt support.
 \\
-===== Programming Example =====
 ===== Configuration Registers =====
-==== CRx ====
+==== USART_CR1 - Configuration register 1 ====
-=== CR1 ===
-Configuration register 1
 \\ {{usart_reg_cr1.svg}} \\ \\
@@ Line 43: / Line 37: @@
 \\
-=== CR2 ===
+==== USART_CR2 - Configuration register 2 ====
-Configuration register 2
 \\ {{usart_reg_cr2.svg}} \\ \\
@@ Line 56: / Line 48: @@
 \\
-==== BRR ====
+==== USART_BRR - Baud rate register ====
-Baud rate register
 \\ {{usart_reg_brr.svg}} \\ \\
@@ Line 69: / Line 59: @@
 ===== Status Register =====
-==== SR ====
+==== USART_SR -  Status register ====
 \\ {{usart_reg_sr.svg}} \\ \\
@@ Line 84: / Line 74: @@
 ===== Data Register =====
-==== DR ====
+==== USART_DR - Data register ====
 \\ {{usart_reg_dr.svg}} \\ \\
@@ Line 92: / Line 82: @@
 \\
-===== Legend =====
-\\ {{legende.svg}} \\ \\
+===== Programming Example =====
+==== Setup GPIO ====
+<code c>
+#include "reg_stm32f4xx.h"
+RCC->AHBENR[0] |= (0x1 << 0u);       /* Enable GPIOA clock */
+/* Configure GPIO pin A.0 and A.1 in alternate function mode. */
+GPIOA->MODER &= ~(0xf << 0u);        /* Clear existing mode bits 0 to 3. */
+GPIOA->MODER |= (0xa << 0u);         /* Set pin 0..1 to alternate function mode. */
+GPIOA->OSPEEDR &= ~(0xff << 0u);     /* Clear existing output speed bits 0 to 3. */
+GPIOA->OSPEEDR |= (0xff << 0u);      /* Set pin 0..1 to high speed (100MHz) mode. */
+GPIOA->AFR[0] &= ~(0xff << 0u);      /* Clear existing af bits 0 to 7. */
+GPIOA->AFR[0] |= (0x88 << 0u);       /* Set pin 0..1 to AF8 (UART4). */
+</code>
+\\
+==== Transmitting Data ====
+<code c>
+#include "reg_stm32f4xx.h"
+RCC->APBENR[0] |= (0x1 << 19u);      /* Enable UART4 clock */
+UART4->CR1 |= (0x1 << 13u);          /* Enable UART */
+UART4->BRR |= (42000000 / 115200);   /* Set baudrate to 115'200 */
+UART4->CR1 |= (0x1 << 3u);           /* Enable transmission */
+UART4->DR = data_send[0];            /* Send first data */
+while(!(UART4->SR & (0x1 << 7u)));   /* Wait til TXE flag is set */
+UART4->DR = data_send[1];            /* Send first data */
+while(!(UART4->SR & (0x1 << 7u)));   /* Wait til TXE flag is set */
+UART4->DR = data_send[2];            /* Send last data */
+while(!(UART4->SR & (0x1 << 6u)));   /* Wait til TC flag is set */
+</code>
+\\
+==== Receiving Data ====
+<code c>
+#include "reg_stm32f4xx.h"
+RCC->APBENR[0] |= (0x1 << 19u);      /* Enable UART4 clock */
+UART4->CR1 |= (0x1 << 13u);          /* Enable UART */
+UART4->BRR |= (42000000 / 115200);   /* Set baudrate to 115'200 */
+UART4->CR1 |= (0x1 << 2u);           /* Enable receiver */
+while(!(UART4->SR & (0x1 << 5u)));   /* Wait til RXNE flag is set */
+data_received = UART4->DR            /* Read data */
+</code>
+\\