ManuelW/grbl-LPC-CoreXY
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flossed the serial module

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Simen Svale Skogsrud 2011-06-03 15:42:28 +02:00
parent 9488cb329c
commit bfe7a2ad84
1 changed files with 6 additions and 5 deletions
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9
serial.c
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@ -71,13 +71,12 @@ void serial_write(uint8_t data) {
tx_buffer[tx_buffer_head] = data; tx_buffer[tx_buffer_head] = data;
tx_buffer_head = next_head; tx_buffer_head = next_head;
// Enable Data Register Empty Interrupt // Enable Data Register Empty Interrupt to make sure tx-streaming is running
UCSR0B |= (1 << UDRIE0); UCSR0B |= (1 << UDRIE0);
} }
// Data Register Empty Interrupt handler // Data Register Empty Interrupt handler
SIGNAL(USART_UDRE_vect) { SIGNAL(USART_UDRE_vect) {
// temporary tx_buffer_tail (to optimize for volatile) // temporary tx_buffer_tail (to optimize for volatile)
uint8_t tail = tx_buffer_tail; uint8_t tail = tx_buffer_tail;
@ -87,15 +86,17 @@ SIGNAL(USART_UDRE_vect) {
// Update tail position // Update tail position
tail ++; tail ++;
tail %= TX_BUFFER_SIZE; tail %= TX_BUFFER_SIZE;
tx_buffer_tail = tail;
// Turn off Data Register Empty Interrupt if this concludes the transfer // Turn off Data Register Empty Interrupt to stop tx-streaming if this concludes the transfer
if (tail == tx_buffer_head) { UCSR0B &= ~(1 << UDRIE0); } if (tail == tx_buffer_head) { UCSR0B &= ~(1 << UDRIE0); }
tx_buffer_tail = tail;
} }
uint8_t serial_read() uint8_t serial_read()
{ {
if (rx_buffer_head != rx_buffer_tail) { if (rx_buffer_head != rx_buffer_tail) {
// Return magic number if no data pending
return 0xff; return 0xff;
} else { } else {
uint8_t data = rx_buffer[rx_buffer_tail]; uint8_t data = rx_buffer[rx_buffer_tail];