9.
Read Operations
Read operations are initiated the same way as write operations with the exception that the read/write select bit in the
device address word is set to one. There are three read operations:
?
?
?
Current Address Read
Random Address Read
Sequential Read.
Current Address Read: The internal data word address counter maintains the last address accessed during the last
read or write operation, incremented by one. This address stays valid between operations as long as the chip power is
maintained. The address roll-over during read is from the last byte of the last memory page to the first byte of the first
page. The address roll-over during write is from the last byte of the current page to the first byte of the same page.
Once the device address with the read/write select bit set to one is clocked in and acknowledged by the EEPROM, the
current address data word is serially clocked out. The microcontroller does not respond with an zero but does generate a
following Stop condition (see Figure 9-3 on page 11 ).
Random Read: A Random Read requires a dummy byte write sequence to load in the data word address. Once the
device address word and data word address are clocked in and acknowledged by the EEPROM, the microcontroller must
generate another start condition. The microcontroller now initiates a Current Address Read by sending a device address
with the read/write select bit high. The EEPROM acknowledges the device address and serially clocks out the data word.
The microcontroller does not respond with a zero but does generate a following stop condition (see Figure 9-4 on page
11 ).
Sequential Read: Sequential Reads are initiated by either a Current Address Read or a Random Address Read. After
the microcontroller receives a data word, it responds with an acknowledge. As long as the EEPROM receives an
acknowledge, it will continue to increment the data word address and serially clock out sequential data words. When the
memory address limit is reached, the data word address will roll-over and the Sequential Read will continue. The
Sequential Read operation is terminated when the microcontroller does not respond with a zero but does generate a
following stop condition (see Figure 9-5 on page 11 ).
Figure 9-1. Byte Write
S
W
T
R
S
A
R
Device
I
T
T
O
T
Address
E
Word Address
Data
P
SDA LINE
M
S
B
R A
/ C
W K
A
C
K
A
C
K
Figure 9-2. Page Write
S
W
T
R
S
A
R
Device
I
T
Word
T
O
T
Address
E
Address (n)
Data (n)
Data (n + 1)
Data (n + x)
P
SDA LINE
M
S
B
R A
/ C
W K
A
C
K
A
C
K
A
C
K
A
C
K
Atmel AT24C01C/02C [DATASHEET]
8700F–SEEPR–6/12
10
相关PDF资料
AT24C04AN-10SI-2.7 IC EEPROM 4KBIT 400KHZ 8SOIC
AT24C08B-PU IC EEPROM 8KBIT 1MHZ 8DIP
AT24C1024B-TH25-B IC EEPROM 1MBIT 1MHZ 8TSSOP
AT24C1024Y4-10YU-2.7 IC EEPROM 1MBIT 1MHZ 8SAP
AT24C11Y1-10YU-1.8 IC EEPROM 1KBIT 1MHZ 8MAP
AT24C128BY6-YH-T IC EEPROM 128KBIT 1MHZ 8DFN
AT24C128C-XHM-B IC EEPROM 128KBIT 400KHZ 8TSSOP
AT24C128Y1-10YU-1.8 IC EEPROM 128KBIT 400KHZ 8MAP
相关代理商/技术参数
AT24C02C-XHM-T 功能描述:电可擦除可编程只读存储器 PB/HALO free NiPdAu, 1.7V 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
AT24C02D-CUM-T 功能描述:IC EEPROM 2KBIT 1MHZ 8VFBGA 制造商:microchip technology 系列:- 包装:带卷(TR) 零件状态:在售 存储器类型:非易失 存储器格式:EEPROM 技术:EEPROM 存储容量:2Kb (256 x 8) 时钟频率:1MHz 写周期时间 - 字,页:5ms 访问时间:4.5μs 存储器接口:I2C 电压 - 电源:1.7 V ~ 3.6 V 工作温度:-40°C ~ 85°C(TC) 安装类型:表面贴装 封装/外壳:8-VFBGA 供应商器件封装:8-VFBGA(1.5x2) 标准包装:5,000
AT24C02D-MAHM-T 制造商:Atmel Corporation 功能描述:Atmel AT24C02D-MAHM-T EEPROM 制造商:Atmel Corporation 功能描述:IC EEPROM 2KBIT 1MHZ 8MINIMAP
AT24C02D-PUM 制造商:Atmel Corporation 功能描述:IC EEPROM 2KBIT 1MHZ 8DIP
AT24C02D-SSHM-B 制造商:Atmel Corporation 功能描述:IC EEPROM 2KBIT 1MHZ 8SOIC
AT24C02D-SSHM-T 制造商:Atmel Corporation 功能描述:Atmel AT24C02D-SSHM-T EEPROM
AT24C02D-STUM-T 功能描述:IC EEPROM 2KBIT 1MHZ SOT23-5 制造商:atmel 系列:- 包装:剪切带(CT) 零件状态:有效 格式 - 存储器:EEPROMs - 串行 存储器类型:EEPROM 存储容量:2K(256 x 8) 速度:400kHz,1MHz 接口:I2C,2 线串口 电压 - 电源:1.7 V ~ 3.6 V 工作温度:-40°C ~ 85°C(TC) 封装/外壳:SOT-23-5 细型,TSOT-23-5 供应商器件封装:SOT-23-5 标准包装:1
AT24C02D-XHM-B 制造商:Atmel Corporation 功能描述:IC EEPROM 2KBIT 1MHZ 8TSSOP