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ECE 477 Final Report Spring 2004
// USART1 Receiver interrupt service routine
#pragma savereg-
interrupt [USART1_RXC] void uart1_rx_isr(void)
{
char status,data;
#asm
push r26
push r27
push r30
push r31
in r26,sreg
push r26
#endasm
status=UCSR1A;
data=UDR1;
if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
{
rx_buffer1[rx_wr_index1]=data;
if (++rx_wr_index1 == RX_BUFFER_SIZE1) rx_wr_index1=0;
if (++rx_counter1 == RX_BUFFER_SIZE1)
{
rx_counter1=0;
rx_buffer_overflow1=1;
};
};
#asm
pop r26
out sreg,r26
pop r31
pop r30
pop r27
pop r26
#endasm
}
#pragma savereg+
// Get a character from the USART1 Receiver buffer
#pragma used+
char getchar1(void)
{
char data;
while (rx_counter1==0);
data=rx_buffer1[rx_rd_index1];
if (++rx_rd_index1 == RX_BUFFER_SIZE1) rx_rd_index1=0;
#asm("cli")
--rx_counter1;
#asm("sei")
return data;
}
#pragma used-
// Write a character to the USART1 Transmitter
#pragma used+
void putchar1(char c)
{
while ((UCSR1A & DATA_REGISTER_EMPTY)==0);
UDR1=c;
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