What is TM key card ds1990 ibutton ?

 —- An iButton is a computer chip which is enclosed in a 16mm thick durable weather resistant

stainless steel can. Because of their small size and extreme durability, iButtons can travel virtually anywhere.

How does an TM key card ds1990 ibutton communicate?

The iButton is a slave device and requires a master to initiate communication to it. A master can be a PC or a micro processor. With the master constantly polling the iButtons, communication to iButtons can be started by a simple touch to a 1-Wire interface called a Blue Dot Receptor. Every iButton has a unique 64-bit serial number, which gives it a unique 1-Wire network address.

What are TM key card ds1990 ibuttons being used for?

iButtons are frequently attached to key fobs, rings, watches, or other personal items for applications such as access control to buildings and computers. Additionally, iButtons are commonly mounted to storage crates, trucks, and other equipment for asset management. Furthermore, iButtons are mounted to refrigeration units, outdoor environments, and even to animals for various data logging tasks