资料下载
×
Reading and Writing iButtons v
消耗积分:3 |
格式:rar |
大小:444 |
2009-04-27
好名字
分享资料个
An iButtonTM is a chip housed in a stainless steel enclosure. The electrical interface is reduced to the absolute minimum, i.e., a single data line plus a ground reference. The energy needed for operation is either ì stolenî from the data line (ì parasitic powerî ) or is taken from an embedded lithium cell. The logical functions range from a simple serial number to password-protected memory, to 64 kbits and beyond of nonvolatile RAM or EPROM, to a Temperature iButton, to a real time clock plus 4 kbits of nonvolatile RAM. Common to all iButtons is a globally unique registration number, the serial 1-WireTM protocol, presence detect, and communication in discrete time slots. Table 1 gives an overview of the available devices.For read operations all devices are satisfied with a 5 k pullup resistor to supply energy and to terminate the 1-Wire bus. iButton devices based on nonvolatile RAM (DS1991 to DS1996) can also be written using this same interface. Due to their different technology, EPROM-based iButtons (DS1982 to DS1986) also require pulses of up to 12V for programming. Since they cannot be erased, EPROM iButtons are referred to as Add-Only Memories. Another device, the DS1920 Temperature iButton, gets its energy for temperature conversion through a low-impedance, active pullup to 5V. Different requirements for writing or special functions are the reason for several types of interfaces.
声明：本文内容及配图由入驻作者撰写或者入驻合作网站授权转载。文章观点仅代表作者本人，不代表电子发烧友网立场。文章及其配图仅供工程师学习之用，如有内容侵权或者其他违规问题，请联系本站处理。 举报投诉
评论(0)
发评论
- 相关下载
- 相关文章
