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WIP: uart: Byteverlust bei der Übertragung #9

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WIP: uart: Byteverlust bei der Übertragung #9

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8bed903
uart tx ready fix; check if queue empty before immediate write to reg…
swappad May 14, 2021
c81c288
falsch auskommentiert rückgängig gemacht
swappad May 19, 2021
737f3d4
Update uart.c
swappad May 20, 2021
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7 changes: 4 additions & 3 deletions uart.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@
#define SINGLE_UART 1
#endif

#define RING_BUFFER_SIZE 64
#define RING_BUFFER_SIZE 128

#define MIN_U2X_BAUD (F_CPU/(16*(255 + 1)) + 1)

Expand Down Expand Up @@ -120,11 +120,12 @@ void uart_send_byte(uint8_t id, uint8_t data) {
#if SINGLE_UART
id = 0;
#endif
if (instances[id].ready) { // Can send directly
instances[id].ready = false;
if (instances[id].ready && (instances[id].head == instances[id].tail)) { // Can send directly
instances[id].ready = false; // Luca: indicate queue not empty
*instances[id].udr = data;
} else if (instances[id].tail != instances[id].head
|| !instances[id].full) { // Not empty but needs to be added to queue
instances[id].ready = false; // Luca: indicate queue not empty
instances[id].data[instances[id].head] = data;
instances[id].head = (instances[id].head + 1) % RING_BUFFER_SIZE;
if (instances[id].tail == instances[id].head) {
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instances[id].head == instances[id].tail vs. instances[id].tail != instances[id].head

Wann ist die Queue

  • leer ?
  • nicht leer ?
  • voll ?

instances[id].head == instances[id].tail wird verwendet für Queue leer und Queue voll. Passt das?

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Wenn Queue voll oder leer ist gilt jeweils head==tail, um das zu unterscheiden gibt es noch den full bool.

Ready wird nur genutzt um zu checken ob die UART Hardware gerade bereit zur Nutzung ist (für den Fall Queue Empty aber Transaktion noch nicht fertig)

Expand Down