Rewritable TM Key Card RW1990 / RW2004 / TM01A iButton Key

TM Card Overview  

The basic principles of TM cards: A TM card is similar to a button battery in shape and can be inlaid into a card, key button and other objects.

You can replace the data line, address line, control line and power line with a single line so that TM card achieves single line communication through a multi-function device. When the host is powered, TM card gives the response to the host through switching the impedances between 50Ω and 500,000Ω. The lengths of time the signal is pulled down(long or short) show the digital logics(long=1, short=0). Due to the range of witching impedances is 1-10,000, the resistances of the contact points will not affect the identification of the digital signals.

According to whether the Memory in TM card is encrypted or not, TM card can be divided into encrypted TM card and non-encrypted TM card.

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