最新免费av在线观看,亚洲综合一区成人在线,中文字幕精品无码一区二区三区,中文人妻av高清一区二区,中文字幕乱偷无码av先锋

DS1982 Datasheet

  • DS1982

  • UniqueWare iButtonTM

  • Dallas   Dallas

掃碼查看芯片數(shù)據(jù)手冊

上傳產(chǎn)品規(guī)格書

PDF預(yù)覽

DS1982
Skip ROM [CCh]
This command can save time in a single-drop bus system by allowing the bus master to access the
memory functions without providing the 64-bit ROM code. If more than one slave is present on the bus
and a read command is issued following the Skip ROM command, data collision will occur on the bus as
multiple slaves transmit simultaneously (open drain pull鈥揹owns will produce a wired-AND result).
Search ROM [F0h]
When a system is initially brought up, the bus master might not know the number of devices on the 1-
Wire bus or their 64-bit ROM codes. The search ROM command allows the bus master to use a process
of elimination to identify the 64-bit ROM codes of all slave devices on the bus. The ROM search process
is the repetition of a simple, three-step routine: read a bit, read the complement of the bit, then write the
desired value of that bit. The bus master performs this simple, three-step routine on each bit of the ROM.
After one complete pass, the bus master knows the contents of the ROM in one device. The remaining
number of devices and their ROM codes may be identified by additional passes. See Chapter 5 of the
Book of DS19xx iButton Standards for a comprehensive discussion of a ROM search, including an actual
example.
1-Wire Signaling
The DS1982 requires strict protocols to ensure data integrity. The protocol consists of five types of
signaling on one line: Reset Sequence with Reset Pulse and Presence Pulse, Write 0, Write 1, Read Data
and Program Pulse. All these signals except presence pulse are initiated by the bus master. The
initialization sequence required to begin any communication with the DS1982 is shown in Figure 10. A
Reset Pulse followed by a presence pulse indicates the DS1982 is ready to accept a ROM command. The
bus master transmits (TX) a Reset Pulse (t
RSTL
, minimum 480
碌s).
The bus master then releases the line
and goes into receive mode (RX). The 1-Wire bus is pulled to a high state via the pullup resistor. After
detecting the rising edge on the 1-Wire line, the DS1982 waits (t
PDH
, 15-60
碌s)
and then transmits the
presence pulse (t
PDL
, 60-240
碌s).
Read/Write Time Slots
The definitions of write and read time slots are illustrated in Figure 11. All time slots are initiated by the
master driving the data line low. The falling edge of the data line synchronizes the DS1982 to the master
by triggering a delay circuit in the DS1982. During write time slots, the delay circuit determines when the
DS1982 will sample the data line. For a read data time slot, if a 0 is to be transmitted, the delay circuit
determines how long the DS1982 will hold the data line low overriding the 1 generated by the master. If
the data bit is a 1, the device will leave the read data time slot unchanged
.
PROGRAM PULSE
To copy data from the 8-bit scratchpad to the EPROM Data or Status Memory, a program pulse of 12
volts is applied to the data line after the bus master has confirmed that the CRC for the current byte is
correct. During programming, the bus master controls the transition from a state where the data line is
idling high via the pullup resistor to a state where the data line is actively driven to a programming
voltage of 12 volts providing a minimum of 10 mA of current to the DS1982. This programming voltage
(Figure 12) should be applied for 480
碌s,
after which the bus master returns the data line to an idle high
state controlled by the pullup resistor. Note that due to the high voltage programming requirements for
any 1-Wire EPROM device, it is not possible to multidrop non-EPROM based 1-Wire devices with the
DS1982 during programming. An internal diode within the non-EPROM based 1-Wire devices will
attempt to clamp the data line at approximately 8 volts and could potentially damage these devices.
18 of 23

DS1982 PDF文件相關(guān)型號

DS1982U,DS1985,DS1985U,DS1986U

DS1982相關(guān)型號PDF文件下載

您可能感興趣的PDF文件資料

熱門IC型號推薦

掃碼下載APP，
一鍵連接廣大的電子世界。

在線人工客服

買家服務(wù)：
賣家服務(wù)：
技術(shù)客服：

0571-85317607

網(wǎng)站技術(shù)支持

13606545031

客服在線時間周一至周五
9:00-17:30

關(guān)注官方微信號，
第一時間獲取資訊。

建議反饋
返回頂部

建議反饋

聯(lián)系人：

聯(lián)系方式：

按住滑塊，拖拽到最右邊
>>
感謝您向阿庫提出的寶貴意見，您的參與是維庫提升服務(wù)的動力！意見一經(jīng)采納，將有感恩紅包奉上哦！