AD7156 Analog Devices, AD7156 Datasheet - Page 23

• Manufacturer Part Number: AD7156
• Manufacturer: Analog Devices

Specifications of AD7156

• Resolution (bits): 12bit
• # Chan: 2
• Sample Rate: 100SPS
• Interface: I²C/Ser 2-Wire,Ser
• Analog Input Type: Capacitive
• Ain Range: 0.5 pF,1 pF,2 pF,4 pF
• Pkg Type: CSP

If a repeated start condition is encountered after the address
pointer byte, all peripherals connected to the bus respond exactly
as outlined previously for a start condition; that is, a repeated
start condition is treated the same as a start condition. When a
master device issues a stop condition, it relinquishes control of
the bus, allowing another master device to take control of the
bus. Therefore, a master wanting to retain control of the bus
issues successive start conditions known as repeated start
conditions.
AD7156 RESET
To reset the AD7156 without having to reset the entire serial
bus, an explicit reset command is provided. This uses a particular
address pointer word as a command word to reset the part and
upload all default settings. The AD7156 does not respond to the
serial bus commands (do not acknowledge) during the default
values upload for approximately 2 ms.
The reset command address word is 0xBF.
SEQUENCE
SEQUENCE
WRITE
READ
S SLAVE ADDR A(S)
S SLAVE ADDR A(S)
S = START BIT
P = STOP BIT
SDA
SCL
LSB = 0
START ADDR R/W ACK SUBADDRESS ACK
S
A(S) = ACKNOWLEDGE BY SLAVE
A(M) = ACKNOWLEDGE BY MASTER
SUB ADDR
SUB ADDR
1 – 7
8
Figure 41. Write and Read Sequences
A(S)
A(S) S SLAVE ADDR
9
Figure 40. Bus Data Transfer
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1 – 7
DATA
8
LSB = 1
A(S)
9
A(S) = NO ACKNOWLEDGE BY SLAVE
A(M) = NO ACKNOWLEDGE BY MASTER
GENERAL CALL
When a master issues a slave address consisting of seven 0s
with the eighth bit (R/W) set to 0, this is known as the general
call address. The general call address is for addressing every
device connected to the serial bus. The AD7156 acknowledges
this address and reads in the following data byte.
If the second byte is 0x06, the AD7156 is reset, completely
uploading all default values. The AD7156 does not respond
to the serial bus commands (do not acknowledge) during the
default values upload for approximately 2 ms.
The AD7156 does not acknowledge any other general call
commands.
A(S)
1 – 7
DATA
DATA
8
ACK
DATA
9
A(M)
STOP
P
A(S)
P
DATA
A(M)
P
AD7156