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117 lines
2.7 KiB
117 lines
2.7 KiB
/* Emulates a DS18B20 using a DHT22 |
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* |
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* Provided by Destroyedlolo. (http://destroyedlolo.info) |
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* |
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* 23/03/2018 - First version |
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*/ |
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#include <Arduino.h> |
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#include <LowLevel.h> |
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#include <OneWireSlave.h> |
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Pin oneWireData(2); // Where the 1-wire bus is connected to |
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const byte owROM[7] = { 0x28, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 }; |
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enum OW_Cmd { |
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START_CONVERSION = 0x44, |
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READ_SCRATCHPAD = 0xBE |
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}; |
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volatile byte scratchpad[9]; |
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/* |
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* DHT22 related |
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*/ |
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#include <SimpleDHT.h> // https://github.com/winlinvip/SimpleDHT |
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SimpleDHT22 DHT; |
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#define pinDHT 3 |
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/* |
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* Let's go |
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*/ |
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#define DEBUG // Comment out to be silence |
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enum DeviceState { |
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WAIT4RESET, |
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WAIT4COMMAND, |
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CONVERTING, |
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TEMPERATUREREADY |
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}; |
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volatile DeviceState state = DeviceState::WAIT4RESET; |
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void owRcv( OneWireSlave::ReceiveEvent evt, byte cmd ){ |
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switch( evt ){ |
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case OneWireSlave::RE_Reset: |
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state = DeviceState::WAIT4COMMAND; |
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break; |
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case OneWireSlave::RE_Error: |
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state = DeviceState::WAIT4RESET; |
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break; |
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case OneWireSlave::RE_Byte: |
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switch( cmd ){ |
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case OW_Cmd::START_CONVERSION: |
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state = DeviceState::CONVERTING; |
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OWSlave.beginWriteBit(0, true); // send zeros as long as the conversion is not finished |
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// consequently, we don't have to take care of race condition as no other command can arrive |
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break; |
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case OW_Cmd::READ_SCRATCHPAD: |
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state = DeviceState::WAIT4RESET; |
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OWSlave.beginWrite((const byte*)scratchpad, 9, 0); |
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break; |
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#ifdef DEBUG |
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default: |
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Serial.print(F("Unknown command :")); |
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Serial.println( cmd, HEX ); |
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#endif |
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} |
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} |
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} |
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void setTemperature( float temp ){ // Write given temperature to the scratchpad |
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int16_t raw = (int16_t)(temp * 16.0f + 0.5f); |
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// We don't care about race condition as well as only one command |
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// can be processed at a time otherwise we are failing in error/collision |
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// condition. |
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scratchpad[0] = (byte)raw; |
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scratchpad[1] = (byte)(raw >> 8); |
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scratchpad[8] = OWSlave.crc8((const byte*)scratchpad, 8); |
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} |
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void setup(){ |
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Serial.begin(115200); // debugging |
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for(int i = 2; i<8; i++) |
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scratchpad[i] = 0; |
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setTemperature( 85 ); |
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OWSlave.setReceiveCallback(&owRcv); |
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OWSlave.begin(owROM, oneWireData.getPinNumber()); |
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} |
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void loop(){ |
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delay(10); |
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// No need to have a local copy of "state" as we are looking |
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// for only one value |
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if(state == DeviceState::CONVERTING){ // start conversion |
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float temperature = 0; |
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float humidite = 0; |
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int err; |
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if((err = DHT.read2(pinDHT, &temperature, &humidite, NULL)) != SimpleDHTErrSuccess){ |
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#ifdef DEBUG |
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Serial.print("\nError while reading, err="); |
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Serial.println(err); |
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#endif |
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temperature = 85; |
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} else |
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setTemperature( temperature ); |
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state = DeviceState::TEMPERATUREREADY; |
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OWSlave.beginWriteBit(1, true); |
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} |
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}
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