First experiments with AVR USART

[mirrors/Programs.git] / avr / usart / main.c

diff --git a/avr/usart/main.c b/avr/usart/main.c
new file mode 100644 (file)
index 0000000..853f82a
--- /dev/null
+++ b/avr/usart/main.c
@@ -0,0 +1,27 @@
+#include <avr/io.h>
+#define F_CPU 1000000UL //1MHz default internal RC oscillator setting
+//util/delay.h and util/setbaud.h
+
+#define USART_BAUDRATE 9600
+#define BAUD_PRESCALE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)
+
+int main (void)
+{
+   char ReceivedByte;
+
+   UCSRB |= (1 << RXEN) | (1 << TXEN);   // Turn on the transmission and reception circuitry
+   //UCSRC |= (1 << URSEL) | (1 << UCSZ0) | (1 << UCSZ1); // Use 8-bit character sizes (not in attiny2313?)
+
+   UBRRH = (BAUD_PRESCALE >> 8); // Load upper 8-bits of the baud rate value into the high byte of the UBRR register
+   UBRRL = BAUD_PRESCALE; // Load lower 8-bits of the baud rate value into the low byte of the UBRR register
+
+   for (;;) // Loop forever
+   {
+      while ((UCSRA & (1 << RXC)) == 0) {}; // Do nothing until data have been received and is ready to be read from UDR
+      ReceivedByte = UDR; // Fetch the received byte value into the variable "ByteReceived"
+
+      while ((UCSRA & (1 << UDRE)) == 0) {}; // Do nothing until UDR is ready for more data to be written to it
+      UDR = ReceivedByte; // Echo back the received byte back to the computer
+   }
+}
+