https://wiki2.sitebuilt.net/index.php?action=history&feed=atom&title=DS18B20_readings_to_JSON 2026-05-06T15:13:50Z Revision history for this page on the wiki MediaWiki 1.37.0 https://wiki2.sitebuilt.net/index.php?title=DS18B20_readings_to_JSON&diff=5944&oldid=prev 2013-01-12T23:20:05Z

<p>Created page with &quot;=====DS18B20 readings to JSON (in serial monitor)===== ::Base code from http://www.pjrc.com/teensy/td_libs_OneWire.html This code in../electronics/Arduino/[https://github.com/...&quot;</p> <p><b>New page</b></p><div>=====DS18B20 readings to JSON (in serial monitor)=====<br /> ::Base code from http://www.pjrc.com/teensy/td_libs_OneWire.html This code in../electronics/Arduino/[https://github.com/mckennatim/arduino/blob/master/DS18B20Serial_json/DS18B20Serial_json.ino DS18B20Serial_json.ino] <br /> :key bits:<br /> You need to allocate a buffer for tempstr<br /> &lt;syntaxhighlight&gt;<br /> float celsius, fahrenheit;<br /> String jsn; <br /> char tempBuf[32] = {0};<br /> &lt;/syntaxhighlight&gt;<br /> You end the json after you've gone through all the sensors and if you are just starting, create a new json string. Otherwise, Increment to next sensor.<br /> &lt;syntaxhighlight&gt;<br /> if ( !ds.search(addr)) {//this is where it loops to the next address<br /> Serial.println(&quot;No more addresses.&quot;);<br /> Serial.println();<br /> jsn = jsn + &quot;}&quot;;//so end the json<br /> Serial.println(jsn);//and print it out<br /> ctr=0;<br /> ds.reset_search();//if there are no more devices go back to start of list<br /> delay(250);<br /> return;<br /> } else {<br /> if (ctr==0){jsn=&quot;{&quot;;}//must be just beginning, start the json str<br /> ++ctr;//since we found a device, increment sensor<br /> }<br /> &lt;/syntaxhighlight&gt;<br /> The first two bytes of data = ds.read() is the sensor raw temp which gets converted here<br /> &lt;syntaxhighlight&gt;<br /> // convert the data to actual temperature<br /> unsigned int raw = (data[1] &lt;&lt; 8) | data[0];<br /> if (type_s) {<br /> raw = raw &lt;&lt; 3; // 9 bit resolution default<br /> if (data[7] == 0x10) {<br /> // count remain gives full 12 bit resolution<br /> raw = (raw &amp; 0xFFF0) + 12 - data[6];<br /> }<br /> } else {<br /> byte cfg = (data[4] &amp; 0x60);<br /> if (cfg == 0x00) raw = raw &lt;&lt; 3; // 9 bit resolution, 93.75 ms<br /> else if (cfg == 0x20) raw = raw &lt;&lt; 2; // 10 bit res, 187.5 ms<br /> else if (cfg == 0x40) raw = raw &lt;&lt; 1; // 11 bit res, 375 ms<br /> // default is 12 bit resolution, 750 ms conversion time<br /> }<br /> celsius = (float)raw / 16.0;<br /> fahrenheit = celsius * 1.8 + 32.0;<br /> dtostrf(fahrenheit, 5, 1, tempBuf); //turns float to string<br /> jsn= jsn + &quot;\&quot;sensor&quot;+ ctr + &quot;\&quot;: &quot; + tempBuf + &quot;, &quot;;//appends temp to json<br /> &lt;/syntaxhighlight&gt;</div>

Tim