milesburton/Arduino-Temperature-Control-Library — pull request #18 by quozl (2014-01-15 10:29:16+00:00)
Title: restore support for DS1820

- the DS1820 (circa 1998) is still in use in some temperature
networks, and can be identified by the double height PR35 package,
and a scratchpad COUNT_PER_C register value that changes during
operation, but not by the family code in the device address,

- fixes a regression introduced in e1cdffb, resulting in sawtooth
temperature graphs for a linear temperature change, caused by using
a fixed COUNT_PER_C register value for DS18S20 and therefore DS1820,

- tested with both DS18S20 and DS1820 sensors.

![shot0063](https://f.cloud.github.com/assets/2936481/1919208/bdb281a4-7dcf-11e3-9057-5df2e44fa275.jpg)