// This should be called on an interrupt timer whose period
// is at most 1/(60*4) seconds (the number of rows times
// POV time)
void leddriver::tickLEDs() {
int x = 0; // For looping
// Turn of LEDS by setting current row to high impedance (aka input mode)
highZRows();
// Increment row being displayed
curLEDrow++;
if (curLEDrow >= 4) curLEDrow = 0;
// Push data out shift register
// Hopefully gcc unrolls this for loop
for(x = 0; x < 8; x++) {
// Zero out data bit
dataLow();
// Add 8 to register if led is active (mod 2 to convert nonzero to 1)
dataSet(ledMatrix[curLEDrow] & (1 << x));
// Latch Data In
latchHigh();
rlatchLow();
latchLow();
rlatchHigh();
}
// Reenable output on new row by outputing a 'sink' on the current row
sinkRow(curLEDrow);
}
static void timerAction(void)
{
/* restart timer */
outp(COUNT_UP, TCNT2); /* value counts up from this to zero */
if (kbd_state < IDLE_END) { // start, wait_rel or ready to tx
dataHigh();
if (!(kbd_flags & FLA_CLOCK_HIGH)) {
kbd_flags |= FLA_CLOCK_HIGH;
clockHigh();
return;
}
/* if clock held low, then we must prepare to start rxing */
if (!readClockPin()) {
kbd_state = IDLE_WAIT_REL;
return;
}
switch(kbd_state) {
case IDLE_START:
kbd_state = IDLE_OK_TO_TX;
return;
case IDLE_WAIT_REL:
if (!readDataPin()) {
/* PC wants to transmit */
kbd_state = RX_START;
return;
}
/* just an ack or something */
kbd_state = IDLE_OK_TO_TX;
return;
case IDLE_OK_TO_TX:
if (kbd_flags & FLA_TX_BYTE) {
dataLow();
kbd_state = TX_START;
}
return;
}
return;
} else // end < IDLE_END
if (kbd_state < RX_END) {
if (!(kbd_flags & FLA_CLOCK_HIGH)) {
kbd_flags |= FLA_CLOCK_HIGH;
clockHigh();
return;
}
/* at this point clock is high in preparation to going low */
if (!readClockPin()) {
/* PC is still holding clock down */
dataHigh();
kbd_state = IDLE_WAIT_REL;
return;
}
switch(kbd_state) {
case RX_START:
/* PC has released clock line */
/* we keep it high for a good half cycle */
kbd_flags &= ~FLA_RX_BAD;
kbd_state++;
return;
case RX_RELCLK:
/* now PC has seen clock high, show it some low */
break;
case RX_DATA0:
kbd_flags &= ~FLA_RX_BYTE;
if (readDataPin()) {
rx_byte = 0x80;
parity = 1;
} else {
parity = 0;
rx_byte = 0;
}
break; /* end clk hi 1 */
case RX_DATA1:
case RX_DATA2:
case RX_DATA3:
case RX_DATA4:
case RX_DATA5:
case RX_DATA6:
case RX_DATA7:
rx_byte >>= 1;
if (readDataPin()) {
rx_byte |= 0x80;
parity++;
}
break; /* end clk hi 2 to 8 */
case RX_PARITY:
if (readDataPin()) {
parity++;
}
if (!(parity & 1)) {
/* faulty, not odd parity */
kbd_flags |= FLA_RX_BAD;
}
break; /* end clk hi 9 */
case RX_STOP:
if (!readDataPin()) {
/* if stop bit not seen */
kbd_flags |= FLA_RX_BAD;
}
if (!(kbd_flags & FLA_RX_BAD)) {
dataLow();
kbd_flags |= FLA_RX_BYTE;
}
break; /* end clk hi 10 */
case RX_SENT_ACK:
dataHigh();
kbd_state = IDLE_START;
/* remains in clk hi 11 */
return;
}
clockLow();
kbd_flags &= ~(FLA_CLOCK_HIGH);
kbd_state++;
return;
} else // end < RX_END
if (kbd_state < TX_END) {
