The TM1990A serial number iButton® is a rugged data carrier that serves as an electronic registration number for automatic identification. Data is transferred serially through the 1-Wire® protocol, which requires only a single data lead and a ground return. Accessories enable the TM1990A iButton to be mounted on almost any object, including containers, pallets, and bags.

Specifications: 

1. Model: TM/DS1990A
2. Size: 17.35mm (diameter) × 6.00mm (height) 
3. 64-bit registration number (8-bit family code + 48- bit serial number + 8-bit CRC tester) 
4. Read/write time :< 5ms
5. Digital identification by momentary contact
6. Chip-based data carrier compactly stores information
7. Data can be accessed while affixed to an object
8. Economically communicates to bus master with a single digital signal at 16.3k bits per second.
9. Button shape is self-aligning with cup-shaped probes
10. Durable stainless steel case engraved with registration number withstands harsh environments.
11. Applications: Access control, work-in-progress tracking, tool management, inventory control, etc.

Included: 1 x iButton with plastic tag (blue, green, yellow, BLACK -- COLOR MAY VARY )

 The iProbe iButton Reader can be found here.

Arduino example code