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--- info:simple_one_wire_driver_circuits [2008/09/07 20:18] – tomgee
+++ info:simple_one_wire_driver_circuits [2008/09/07 20:21] (current) – tomgee
@@ Line 1: / Line 1: @@
 ===== Suggested circuit for driving DS1820 thermometers =====
-//Note://\\
+Note:\\
-Testing has found out that the DS1820 cannot work with parasitic power on 3.3V. An additional wire is needed to power DS1820 sensors during temperature conversion.\\
+Testing has found out that the DS1820 cannot work with parasitic power on 3.3V. An additional wire is needed to power DS1820 sensors during temperature conversion at 3.3V.\\
 {{info:1-wire-pnp.png|}}\\
-This is 1-wire driver with minimal component count. Widely available components are used. One general purpose PNP transistor, there resistors and one DIL socket as connector and component holder. NO PCB is required. Resistors R2 and R3 are inserted for current limiting protection of the processor. Fuse F1 is to prevent possible short circuit. The circuit should work also without R2 and R3 giving only R1 and Q1.\\
+This is a 1-wire driver with minimal component count. Widely available components are used. One general purpose PNP transistor, three resistors and one DIL socket as connector and component holder. NO PCB is required. Resistors R2 and R3 are inserted for current limiting protection of the processor. Fuse F1 is to prevent possible short circuit. The circuit should work also without R2 and R3 leaving only R1 and Q1.\\
 Despite the simplicity of the above 1-wire driver, one can run into troubles. The basic problem of this driver is that the LOW level is intrinsically near the specs of DS1820 and also processor RX pin. In other words; due to V_EB diode, the low output level will be approx 0.7V which is not so good.