support avr architecture based on ATMega32

1. IAR project, see TencentOS-tiny\board\ATMega32\IAR, both 4.12 and 7.20 is supplied.

board/ATMega32/BSP/src/uart.c

@@ -0,0 +1,47 @@
+#include "iom32.h"
+#include "uart.h"
+
+#define F_CPU 16777216
+
+void uart_send_byte(char data)
+{
+    while (!(UCSRA & (1 << UDRE))) {
+        ;
+    }
+    UDR = data;
+}
+
+void uart_send_string(char *string)
+{
+    for(; *string!='\0'; string++) {
+        uart_send_byte(*string);
+    }
+}
+
+unsigned char uart_receive(void)
+{
+    while (!(UCSRA & (1 << RXC))) {
+        ;
+    }
+    return UDR;
+}
+
+int putchar(int data)
+{
+    uart_send_byte(data);
+}
+
+void uart_init(unsigned int baudrate)
+{
+    unsigned int tmp;
+    tmp = F_CPU / baudrate / 16 - 1;
+
+    /* Set baud rate */
+    UBRRH = (unsigned char)(tmp >> 8);
+    UBRRL = (unsigned char)tmp;
+    /* Enable receiver and transmitter, enable receive interrupt */
+    UCSRB = (1 << RXCIE) | (1 << RXEN) | (1 << TXEN);
+    /* 8bit, 1 stopbit */
+    UCSRC = (1 << URSEL) | (1 << UCSZ1) | (1<< UCSZ0);
+}
+