Implement ring buffer and auxiliary functions

src/main.c

@@ -1,22 +1,12 @@
 #include "common.h"
 #include "serial.h"
 
-#include <stdio.h>
 #include <avr/interrupt.h>
 
-#define MAX_CMDBUF 256
-
 int main(void)
 {
 	unsigned long i;
-	char buf[128];
-	char *cmd;
-
-	// UART command buffer
-	cmd = malloc(MAX_CMDBUF);
-	if (cmd == NULL) {
-		return 1;
-	}
+	char ch;
 
 	// Handle USART_RXC interrupt
 	UCSRB |= (1 << RXCIE);
@@ -27,13 +17,10 @@ int main(void)
 	for (i = 1;; i++) {
 		if (i >= 99999) i = 1;
 
-		sprintf(buf, "[CORE] Fetching sensors #%05lu...\r\n", i);
-		USART_Write(buf);
-		USART_Update();
-
-		// USART_Read(&cmd, MAX_CMDBUF);
-		// sprintf(buf, "[CORE] Checking cmdbuf=\"%s\"\r\n", cmd);
-		// USART_Write(buf);
+		ch = USART_GetChar();
+		USART_Printf("[CORE] Fetching sensors #%05lu...\r\n", i);
+		USART_Printf("[CORE] USART_GetChar() = '%c'\r\n",
+			(ch) ? ch : ' ');
 
 		Sleep(3000);
 	}