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DHT11/DHT22 library fixes.

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Fixed temperature below zero.
Fixed checksum overflow verification.
Fixed inconsistent reading of DHT11.
This commit is contained in:
sheinz 2016-07-06 21:01:44 +03:00
parent a41407e3d1
commit 6ff78f802d
2 changed files with 8 additions and 7 deletions
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7
extras/dht/dht.c
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@ -64,13 +64,14 @@ static bool dht_await_pin_state(uint8_t pin, uint32_t timeout,
bool expected_pin_state, uint32_t *duration)
{
for (uint32_t i = 0; i < timeout; i += DHT_TIMER_INTERVAL) {
// need to wait at least a single interval to prevent reading a jitter
sdk_os_delay_us(DHT_TIMER_INTERVAL);
if (gpio_read(pin) == expected_pin_state) {
if (duration) {
*duration = i;
}
return true;
}
sdk_os_delay_us(DHT_TIMER_INTERVAL);
}
return false;
@ -135,7 +136,7 @@ static inline int16_t dht_convert_data(uint8_t msb, uint8_t lsb)
data = msb & 0x7F;
data <<= 8;
data |= lsb;
if (msb & BIT(15)) {
if (msb & BIT(7)) {
data = 0 - data; // convert it to negative
}
#elif DHT_TYPE == DHT11
@ -169,7 +170,7 @@ bool dht_read_data(uint8_t pin, int16_t *humidity, int16_t *temperature)
data[i/8] |= bits[i];
}
if (data[4] != (data[0] + data[1] + data[2] + data[3])) {
if (data[4] != ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) {
debug("Checksum failed, invalid data received from sensor\n");
return false;
}