add projects

labW5barnestr/Src/uart_driver.c

@@ -0,0 +1,92 @@
+/*
+ * uart_driver.c
+ *
+ *  Created on: Nov 8, 2016
+ *      Author: barnekow
+ */
+#include "uart_driver.h"
+#include <inttypes.h>
+#include <stdio.h>
+
+
+// These will override _read and _write in syscalls.c, which are
+// prototyped as weak
+int _read(int file, char *ptr, int len)
+{
+	int DataIdx;
+	// Modified the for loop in order to get the correct behavior for fgets
+	int byteCnt = 0;
+	for (DataIdx = 0; DataIdx < len; DataIdx++)
+	{
+		//*ptr++ = __io_getchar();
+		byteCnt++;
+		//*ptr++ = usart2_getch();
+		*ptr = usart2_getch();
+		if(*ptr == '\n') break;
+		ptr++;
+	}
+
+	//return len;
+	return byteCnt; // Return byte count
+}
+
+int _write(int file, char *ptr, int len)
+{
+	int DataIdx;
+
+	for (DataIdx = 0; DataIdx < len; DataIdx++)
+	{
+		usart2_putch(*ptr++);
+	}
+	return len;
+}
+
+
+
+char usart2_getch(){
+	char c;
+	while((*(USART_SR)&(1<<RXNE)) != (1<<RXNE));
+	c = ((char) *USART_DR);  // Read character from usart
+	usart2_putch(c);  // Echo back
+
+	if (c == '\r'){  // If character is CR
+		usart2_putch('\n');  // send it
+		c = '\n';   // Return LF. fgets is terminated by LF
+	}
+
+	return c;
+}
+
+void usart2_putch(char c){
+	while((*(USART_SR)&(1<<TXE)) != (1<<TXE));
+	*(USART_DR) = c;
+}
+
+void init_usart2(uint32_t baud, uint32_t sysclk){
+	// Enable clocks for GPIOA and USART2
+	*(RCC_AHB1ENR) |= (1<<GPIOAEN);
+	*(RCC_APB1ENR) |= (1<<USART2EN);
+
+	// Function 7 of PORTA pins is USART
+	*(GPIOA_AFRL) &= (0xFFFF00FF); // Clear the bits associated with PA3 and PA2
+	*(GPIOA_AFRL) |= (0b01110111<<8);  // Choose function 7 for both PA3 and PA2
+	*(GPIOA_MODER) &= (0xFFFFFF0F);  // Clear mode bits for PA3 and PA2
+	*(GPIOA_MODER) |= (0b1010<<4);  // Both PA3 and PA2 in alt function mode
+
+	// Set up USART2
+	//USART2_init();  //8n1 no flow control
+	// over8 = 0..oversample by 16
+	// M = 0..1 start bit, data size is 8, 1 stop bit
+	// PCE= 0..Parity check not enabled
+	// no interrupts... using polling
+	*(USART_CR1) = (1<<UE)|(1<<TE)|(1<<RE); // Enable UART, Tx and Rx
+	*(USART_CR2) = 0;  // This is the default, but do it anyway
+	*(USART_CR3) = 0;  // This is the default, but do it anyway
+	*(USART_BRR) = sysclk/baud;
+
+	/* I'm not sure if this is needed for standard IO*/
+	 //setvbuf(stderr, NULL, _IONBF, 0);
+	 //setvbuf(stdin, NULL, _IONBF, 0);
+	 setvbuf(stdout, NULL, _IONBF, 0);
+}
+