void
ps2_init(void)
{
bitcount = 11;
parity = 1;
key.num = 0;
/* Enable the interrupt for the clock pin, because the keyboard is clocking
* us, not vice versa
*/
PCICR |= _BV(PS2_PCIE);
PS2_PCMSK |= PIN_BV(PS2_CLOCK);
DDR_CONFIG_IN(PS2_DATA);
DDR_CONFIG_IN(PS2_CLOCK);
PIN_CLEAR(PS2_DATA);
PIN_CLEAR(PS2_CLOCK);
}
static void
dht_read(void)
{
PIN_SET(DHT);
_delay_us(30);
DDR_CONFIG_IN(DHT);
/* Read in timingss, which takes approx. 4,5 milliseconds.
* We do not disable interrupts, because a failed read is outweighed
* by a non-serviced interrupt. Please never enclose the for-loop
* with an ATOMIC_BLOCK! */
uint8_t last_state = PIN_BV(DHT);
uint8_t j = 0;
uint8_t data[5];
for (uint8_t i = 0; i < MAXTIMINGS; i++)
{
uint8_t counter = 0;
uint8_t current_state;
while (last_state == (current_state = PIN_HIGH(DHT)))
{
_delay_us(5);
if (++counter == 20)
{
DHT_DEBUG("read timeout, edge=%u", i);
return; /* timeout in conversation */
}
}
last_state = current_state;
/* ignore first three transitions */
if ((i >= 4) && (i % 2 == 0))
{
/* shift each bit into the storage bytes */
data[j / 8] <<= 1;
if (counter > 7) /* 7*5=35us */
data[j / 8] |= 1;
j++;
}
}
/* check we read 40 bits and that the checksum matches */
if ((j < 40) ||
(data[4] != ((data[0] + data[1] + data[2] + data[3]) & 0xFF)))
{
DHT_DEBUG("read failed, bits=%u, %02X %02X %02X %02X %02X",
j, data[0], data[1], data[2], data[3], data[4]);
return;
}
int16_t t;
#if DHT_TYPE == DHT_TYPE_11
t = data[2];
t *= 10;
dht_global.temp = t;
t = data[0];
t *= 10;
dht_global.humid = t;
#elif DHT_TYPE == DHT_TYPE_22
t = data[2] << 8 | data[3];
if (t & 0x8000)
{
t &= ~0x8000;
t = -t;
}
dht_global.temp = t;
t = data[0] << 8 | data[1];
dht_global.humid = t;
#endif
DHT_DEBUG("t=%d, h=%d%%", dht_global.temp, dht_global.humid);
}
