Shrink the logger

* Move _write function to the log.c
* Change the way to setup the logger
* Update the readme
* Add terminal commands

project/Core/Src/main.c

@@ -22,8 +22,7 @@
 
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
-#include <errno.h>
-#include <sys/unistd.h>
+#include "log.h"
 /* USER CODE END Includes */
 
 /* Private typedef -----------------------------------------------------------*/
@@ -431,24 +430,6 @@ static void MX_GPIO_Init(void)
 }
 
 /* USER CODE BEGIN 4 */
-int _write(int file, char *data, int len) {
-    HAL_StatusTypeDef status;
-
-    switch (file) {
-        case STDOUT_FILENO:
-        case STDERR_FILENO:
-            status = HAL_UART_Transmit(&huart1, (uint8_t*)data, len, HAL_MAX_DELAY);
-            if (status != HAL_OK) {
-                errno = EIO;
-                return -1;
-            }
-            break;
-        default:
-            errno = EBADF;
-            return -1;
-    }
-    return len;
-}
 /* USER CODE END 4 */
 
 /**