Résumé :
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"Power and Control Share a Link The 1-Wire protocol enables control and power to be accomplished through a single I/O pin. In this project article, Jeff shares the history and evolution of Maxim Integrated’s 1-Wire scheme and how he discovered that special steps need to be taken to ensure you get sufficient power delivery using this technology. Topics Discussed How to understand and use Maxim Integrated's 1-Wire protocolHow 1-Wire protocol worksHow a device is identifiedWhat program functions are needed for 1-Wire communications? Tech Used Maxim Integrated's 1-Wire protocolESP8266 from Espressif SystemsRaspberry PI SBCDS18B20 temperature sensors fr0m Maxim (Dallas Semi) Not to be confused with PoE (Power over Ethernet), Maxim Integrated's 1-Wire protocol handles power and access over the same wire. It's a slight misnomer, because as in most circuits, a ground (return) wire is also required. And, as I learned from this project, there are circumstances where the power gleaned over the same control wire can be insufficient, in some cases requiring a few special manipulations. Let's begin back before Maxim acquired Dallas Semiconductor. The Dallas Semi brand began with communications and mixed-signal products introduced in the 1980s. My first exposure was with the iButton. Manufactured in a tin can the size of a large Li-Ion coin cell, the iButton used a 1-Wire protocol for communication via a single I/O pin. The communication identified any iButton as a specific, 48-bit ID number. Like fingerprint identification, iButtons (Figure 1) were built into rings, tags and other personal items that could be carried around and used to identify a particular person or item." (Extrait de Circuit Cellar n°373)
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