81 lines
1.8 KiB
C
81 lines
1.8 KiB
C
|
#include <avr/interrupt.h>
|
||
|
|
#include "usb_debug.h"
|
||
|
|
|
||
|
|
|
||
|
|
// the time remaining before we transmit any partially full
|
||
|
|
// packet, or send a zero length packet.
|
||
|
|
volatile uint8_t debug_flush_timer=0;
|
||
|
|
|
||
|
|
|
||
|
|
// transmit a character. 0 returned on success, -1 on error
|
||
|
|
int8_t usb_debug_putchar(uint8_t c)
|
||
|
|
{
|
||
|
|
static uint8_t previous_timeout=0;
|
||
|
|
uint8_t timeout, intr_state;
|
||
|
|
|
||
|
|
// if we're not online (enumerated and configured), error
|
||
|
|
if (!usb_configured()) return -1;
|
||
|
|
// interrupts are disabled so these functions can be
|
||
|
|
// used from the main program or interrupt context,
|
||
|
|
// even both in the same program!
|
||
|
|
intr_state = SREG;
|
||
|
|
cli();
|
||
|
|
UENUM = DEBUG_TX_ENDPOINT;
|
||
|
|
// if we gave up due to timeout before, don't wait again
|
||
|
|
if (previous_timeout) {
|
||
|
|
if (!(UEINTX & (1<<RWAL))) {
|
||
|
|
SREG = intr_state;
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
previous_timeout = 0;
|
||
|
|
}
|
||
|
|
// wait for the FIFO to be ready to accept data
|
||
|
|
timeout = UDFNUML + 4;
|
||
|
|
while (1) {
|
||
|
|
// are we ready to transmit?
|
||
|
|
if (UEINTX & (1<<RWAL)) break;
|
||
|
|
SREG = intr_state;
|
||
|
|
// have we waited too long?
|
||
|
|
if (UDFNUML == timeout) {
|
||
|
|
previous_timeout = 1;
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
// has the USB gone offline?
|
||
|
|
if (!usb_configured()) return -1;
|
||
|
|
// get ready to try checking again
|
||
|
|
intr_state = SREG;
|
||
|
|
cli();
|
||
|
|
UENUM = DEBUG_TX_ENDPOINT;
|
||
|
|
}
|
||
|
|
// actually write the byte into the FIFO
|
||
|
|
UEDATX = c;
|
||
|
|
// if this completed a packet, transmit it now!
|
||
|
|
if (!(UEINTX & (1<<RWAL))) {
|
||
|
|
UEINTX = 0x3A;
|
||
|
|
debug_flush_timer = 0;
|
||
|
|
} else {
|
||
|
|
debug_flush_timer = 2;
|
||
|
|
}
|
||
|
|
SREG = intr_state;
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
// immediately transmit any buffered output.
|
||
|
|
void usb_debug_flush_output(void)
|
||
|
|
{
|
||
|
|
uint8_t intr_state;
|
||
|
|
|
||
|
|
intr_state = SREG;
|
||
|
|
cli();
|
||
|
|
if (debug_flush_timer) {
|
||
|
|
UENUM = DEBUG_TX_ENDPOINT;
|
||
|
|
while ((UEINTX & (1<<RWAL))) {
|
||
|
|
UEDATX = 0;
|
||
|
|
}
|
||
|
|
UEINTX = 0x3A;
|
||
|
|
debug_flush_timer = 0;
|
||
|
|
}
|
||
|
|
SREG = intr_state;
|
||
|
|
}
|