AMC6821SDBQG4 Datasheet, PDF (9/56 Pages) Texas Instruments – Intelligent Temperature Monitor and PWM Fan Controller

AMC6821
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SBAS386C – MAY 2006 – REVISED JULY 2007
Table 6. Write Multiple Bytes
S
SLAVE ADDRESS WR ACK
COMMAND
ACK
DATA
ACK
DATA
ACK
7-bit AMC6821 slave
address
8-bit register address of
first register to be written
First 8-bit data written
first register
Second 8-bit data written
second register
DATA
ACK
...
Third 8-bit data written third register
DATA
Last 8-bit data
ACK
P
S = start condition; P = stop condition; shaded = slave to master; unshaded = master to slave; WR = write (bit value of 0).
The first register is the one to which the first data byte is written. The next register is the second register. If the
bus master continues to transfer data into the AMC6821 after writing the last location, all data are ignored until
the operation stops.
Table 7. Read Byte
S SLAVE ADDRESS WR ACK
COMMAND
ACK
7-bit AMC6821 slave
address
8-bit register address
Sr SLAVE ADDRESS RD
7-bit AMC6821 slave
address
ACK
DATA
8-bit data from
register
NACK P
S = start condition; P = stop condition; shaded = slave to master; unshaded = master to slave; WR = write (bit value of 0); RD = read (bit
value of 1);
NACK = not acknowledged; Sr = repeated start condition.
S SLAVE ADDRESS WR ACK
7-bit AMC6821 slave
address
Table 8. Read Multiple Bytes
COMMAND
Address of first
register to be read
ACK Sr SLAVE ADDRESS RD
7-bit AMC6821 slave
address
ACK
DATA
8-bit data from first
register
ACK
DATA
ACK
...
8-bit data from second register
DATA
Last 8-bit data
NACK
P
S = start condition; P = stop condition; shaded = slave to master; unshaded = master to slave; WR = write (bit value of 0); RD = read (bit
value of 1);
NACK = not acknowledged; Sr = repeated start condition.
The first register is the one from which the first data byte is transmitted. The next register is the second register.
If the bus master continues clocking data out after reading the last location (0x3F), the value 0x00 is sent out
until the operation stops.
The AMC6821 is entirely controlled by the registers. All registers are 8-bit. The AMC6821 has an address pointer
register; the value of the address pointer register determines the register to be written to or read from. To write
data to the device register or read data from it, the address pointer register must be set properly. Data can then
be written into or read from that register. The command issued by the bus master always contains the initial
value of the address pointer register. The command is constructed as shown in Table 9.
Table 9. Command Format⁽¹⁾
Bit 7 (MSB)
0
Bit 6
0
Bit 5
ADDR5
Bit 4
ADDR4
Bit 3
ADDR3
Bit 2
ADDR2
Bit 1
ADDR1
Bit 0 (LSB)
ADDR0
(1) ADDR[5:0] is the address of the register that is accessed first. The register address is stored in the address pointer register.
In the send byte operation, the bus master writes the address of a specified device register into the address
pointer register.
In the receive byte operation, the bus master reads the data back from the device register addressed by the
address point register.
In the write byte operation, the bus master sets the address pointer register to the address of a specified device
register, then writes 8-bit data into it. In the read byte operation, the SMBus master sets the address pointer
register to the address of a specified device register first, then reads 8-bit data back from it.
Copyright © 2006–2007, Texas Instruments Incorporated
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