AD7747(RevPrC) Просмотр технического описания (PDF) - Analog Devices
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AD7747 Datasheet PDF : 20 Pages
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Preliminary Technical Data
internal register address. Thus, subsequent transmitted data
bytes are loaded into sequentially incremented addresses.
If a repeated start condition is encountered after the address
pointer byte, all peripherals connected to the bus respond
exactly as outlined above 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. Hence, a master wanting to retain control of the bus issues
successive start conditions known as repeated start conditions.
AD7747 RESET
To reset the AD7747 without having to reset the entire I2C 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 AD7747 does not respond to the
I2C bus commands (do not acknowledge) during the default
values upload for approximately 150 µs (max 200 µs).
The reset command address word is 0xBF.
AD7747
GENERAL CALL
When a master issues a slave address consisting of seven 0s with
the eighth bit (R/W bit) set to 0, this is known as the general call
address. The general call address is for addressing every device
connected to the I2C bus. The AD7747 acknowledges this
address and read in the following data byte.
If the second byte is 0x06, the AD7747 is reset, completely
uploading all default values. The AD7747 does not respond to
the I2C bus commands (do not acknowledge) during the default
values upload for approximately 150 µs (max 200 µs).
The AD7747 does not acknowledge any other general call
commands.
SDATA
SCLOCK S 1–7 8 9
1–7 8 9
1–7 8 9
P
START ADDR R/W ACK SUBADDRESS ACK
DATA ACK STOP
Figure 10. Bus Data Transfer
WRITE
SEQUENCE
S SLAVE ADDR A(S)
SUB ADDR A(S)
LSB = 0
DATA
A(S)
LSB = 1
DATA
A(S) P
READ
SEQUENCE
S SLAVE ADDR A(S) SUB ADDR A(S) S SLAVE ADDR A(S)
DATA
A(M)
DATA
S = START BIT
P = STOP BIT
A(S) = ACKNOWLEDGE BY SLAVE
A(M) = ACKNOWLEDGE BY MASTER
A(S) = NO-ACKNOWLEDGE BY SLAVE
A(M) = NO-ACKNOWLEDGE BY MASTER
Figure 11. Write and Read Sequences
A(M) P
Rev. PrC| Page 11 of 20
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