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--- info:one_wire_temp_conversion [2008/06/23 20:20] – tomgee
+++ info:one_wire_temp_conversion [2008/09/20 11:54] (current) – tomgee
@@ Line 1: / Line 1: @@
+===== Lessons Learned =====
+For the temperature devices, the family code is important. A Family code
+of 0x28 is the 18b20 and contains a 12 bit data register with the least 4 bits
+indicating digits to the right of the decimal point. The 18s20 with a family code
+of 0x10 only has one digit to the right of the decimal point and thus you need to
+account for this in temperature conversions.
+If you don't allow enough time for the device to convert you will read the default
+startup temperature data which is 0x0550 on the DS18b20 and is a default temp of 185 F.
+In addition, when a conversion is started using parasitic power, the bus must be held high
+with a strong pullup. I have been turning the AVR output driver on for this instance.
+===== The Formulas =====
+{{info:c.gif|}}
+{{info:f.gif|}}
 ===== Temperature conversions =====