24LCS21A
3.1
Bidirectional Mode Bus
Characteristics
Each data transfer is initiated with a Start condition and
terminated with a Stop condition. The number of the
data bytes transferred between the Start and Stop
The following bus protocol has been defined:
? Data transfer may be initiated only when the bus
is not busy.
? During data transfer, the data line must remain
stable whenever the clock line is high. Changes in
conditions is determined by the master device and is
theoretically unlimited, although only the last eight will
be stored when doing a write operation. When an
overwrite does occur it will replace data in a first-in first-
out (FIFO) fashion.
the data line while the clock line is high will be
Note:
Once switched into Bidirectional mode, the
interpreted as a Start or Stop condition.
Accordingly, the following bus conditions have been
defined (Figure 3-4).
3.1.1 BUS NOT BUSY (A)
Both data and clock lines remain high.
3.1.2 START DATA TRANSFER (B)
A high-to-low transition of the SDA line while the clock
(SCL) is high determines a Start condition. All
24LCS21A will remain in that mode until
power is removed. Removing power is the
only way to reset the 24LCS21A into the
Transmit-Only mode.
3.1.5 ACKNOWLEDGE
Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this Acknowledge bit.
commands must be preceded by a Start condition.
Note:
The 24LCS21A does not generate any
3.1.3
STOP DATA TRANSFER (C)
Acknowledge bits if an internal
programming cycle is in progress.
A low-to-high transition of the SDA line while the clock
(SCL) is high determines a Stop condition. All
operations must be ended with a Stop condition.
The device that acknowledges has to pull down the
SDA line during the Acknowledge clock pulse in such a
way that the SDA line is stable low during the high
3.1.4
DATA VALID (D)
period of the acknowledge related clock pulse. Of
course, setup and hold times must be taken into
The state of the data line represents valid data when,
after a Start condition, the data line is stable for the
duration of the high period of the clock signal.
The data on the line must be changed during the low
period of the clock signal. There is one clock pulse per
bit of data.
account. A master must signal an end of data to the
slave by not generating an Acknowledge bit on the last
byte that has been clocked out of the slave. In this
case, the slave must leave the data line high to enable
the master to generate the Stop condition.
FIGURE 3-4:
DATA TRANSFER SEQUENCE ON THE SERIAL BUS
SCL
(A)
(B)
(D)
(D)
(C)
(A)
SDA
Start
Condition
? 2007 Microchip Technology Inc.
Address or
Acknowledge
Valid
Data
Allowed
to Change
Stop
Condition
DS21161H-page 7
相关PDF资料
24LCS22A-I/P IC EEPROM 2KBIT 400KHZ 8DIP
24VL014/SN IC EEPROM 1KBIT 400KHZ 8SOIC
24VL014H/SN IC EEPROM 1KBIT 400KHZ 8SOIC
24VL024/SN IC EEPROM 2KBIT 400KHZ 8SOIC
24VL024H/SN IC EEPROM 2KBIT 400KHZ 8SOIC
25A512-I/ST IC EEPROM 512K SPI BUS 8TSSOP
25AA020A-I/MS IC EEPROM 2KBIT 10MHZ 8MSOP
25AA02E48-I/SN IC EEPROM 2KBIT 10MHZ 8SOIC
相关代理商/技术参数
24LCS21A/S 制造商:Microchip Technology Inc 功能描述:1K 2.5V DUAL MODE SERIAL EEPRO - Gel-pak, waffle pack, wafer, diced wafer on film
24LCS21A/SN 功能描述:电可擦除可编程只读存储器 2.5V Dual Mode RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
24LCS21A/W 制造商:Microchip Technology Inc 功能描述:1K 2.5V DUAL MODE SERIAL EEPROM WAFER - Gel-pak, waffle pack, wafer, diced wafer on film
24LCS21A/WF 制造商:Microchip Technology Inc 功能描述:1K 2.5V DUAL MODE SERIAL EEPRO - Gel-pak, waffle pack, wafer, diced wafer on film
24LCS21A-I/P 功能描述:电可擦除可编程只读存储器 2.5V Dual Mode RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
24LCS21A-I/PG 功能描述:电可擦除可编程只读存储器 2.5V Dual Mode Lead Free Package RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
24LCS21A-I/SN 功能描述:电可擦除可编程只读存储器 2.5V Dual Mode RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8
24LCS21A-I/SNG 功能描述:电可擦除可编程只读存储器 2.5V Dual Mode Lead Free Package RoHS:否 制造商:Atmel 存储容量:2 Kbit 组织:256 B x 8 数据保留:100 yr 最大时钟频率:1000 KHz 最大工作电流:6 uA 工作电源电压:1.7 V to 5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8