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node_modules/i2c-bus/example/ds1621-sync.js

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+'use strict';
+
+const i2c = require('../');
+
+const DS1621_ADDR = 0x48;
+const CMD_ACCESS_CONFIG = 0xac;
+const CMD_READ_TEMP = 0xaa;
+const CMD_START_CONVERT = 0xee;
+
+const toCelsius = rawTemp => {
+  const halfDegrees = ((rawTemp & 0xff) << 1) + (rawTemp >> 15);
+
+  if ((halfDegrees & 0x100) === 0) {
+    return halfDegrees / 2; // Temp +ve
+  }
+
+  return -((~halfDegrees & 0xff) / 2); // Temp -ve
+};
+
+const displayTemperature = _ => {
+  const i2c1 = i2c.openSync(1);
+
+  // Enter one shot mode (this is a non volatile setting)
+  i2c1.writeByteSync(DS1621_ADDR, CMD_ACCESS_CONFIG, 0x01);
+
+  // Wait while non volatile memory busy
+  while (i2c1.readByteSync(DS1621_ADDR, CMD_ACCESS_CONFIG) & 0x10) {
+  }
+
+  // Start temperature conversion
+  i2c1.sendByteSync(DS1621_ADDR, CMD_START_CONVERT);
+
+  // Wait for temperature conversion to complete
+  while ((i2c1.readByteSync(DS1621_ADDR, CMD_ACCESS_CONFIG) & 0x80) === 0) {
+  }
+
+  // Display temperature
+  const rawTemp = i2c1.readWordSync(DS1621_ADDR, CMD_READ_TEMP);
+  console.log('temp: ' + toCelsius(rawTemp));
+
+  i2c1.closeSync();
+};
+
+displayTemperature();
+