91 lines
1.9 KiB
C++
91 lines
1.9 KiB
C++
#include "dht11.h"
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Dht11::Dht11(volatile unsigned char * const port, volatile unsigned char * const inPort,
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volatile unsigned char * const port_ctl, const unsigned char pin): _port(port), _port_ctl(port_ctl), _inPort(inPort),
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_pin(pin)
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{}
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uint8_t Dht11::read()
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{
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// BUFFER TO RECEIVE
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uint8_t bits[5];
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uint8_t cnt = 7;
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uint8_t idx = 0;
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// EMPTY BUFFER
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for (uint8_t i=0; i< 5; i++) bits[i] = 0;
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// REQUEST SAMPLE
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setDirection(_port_ctl, _pin, true);
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writePin(_port, _pin, false);
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_delay_ms(18);
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writePin(_port, _pin, true);
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setDirection(_port_ctl, _pin, false);
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_delay_us(42);
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// ACKNOWLEDGE or TIMEOUT
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unsigned int loopCnt = LOOP_TIMEOUT_COUNT;
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while(!readPin(_inPort, _pin)) if (loopCnt-- == 0) return 1;
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loopCnt = LOOP_TIMEOUT_COUNT;
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while(readPin(_inPort, _pin) ) if (loopCnt-- == 0) return 2;
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PORTD |= 1 << PD1;
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PORTD &= ~(1 << PD1);
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PORTD |= 1 << PD1;
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PORTD &= ~(1 << PD1);
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// READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
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for (uint8_t i=0; i<40; i++)
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{
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loopCnt = LOOP_TIMEOUT_COUNT;
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while(!readPin(_inPort, _pin))
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if (loopCnt-- == 0)
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{
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PORTD |= 1 << PD1;
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return 3;
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}
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loopCnt = 0;
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while(readPin(_inPort, _pin))
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{
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_delay_us(10);
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if (loopCnt++ > LOOP_TIMEOUT_SMALL_COUNT) return 4;
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}
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if( loopCnt > BIT_COUNT )
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{
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PORTD |= 1 << PD1;
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PORTD &= ~(1 << PD1);
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bits[idx] |= (1 << cnt);
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}
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if (cnt == 0) // next byte?
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{
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cnt = 7; // restart at MSB
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idx++; // next byte!
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}
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else cnt--;
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}
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uint8_t sum;
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if constexpr(DHT22) sum= bits[0] + bits[1] + bits[2] + bits[3];
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else sum = bits[0] + bits[2];
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if((bits[4] == sum && sum != 0) || true)
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{
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if constexpr(DHT22)
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{
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humidity = (static_cast<uint16_t>(bits[0]) << 8) + bits[1];
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temperature = (static_cast<uint16_t>((bits[2] & 0b01111111) << 8) + bits[3]);
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if(bits[2] & 0b10000000) temperature=temperature*-1;
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}
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else
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{
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humidity = bits[0]*10;
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temperature = bits[2]*10;
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}
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return 0;
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}
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else return 5;
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}
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