NCT210

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before the 10th clock pulse, then high during the

10th clock pulse to assert a stop condition.

Any number of bytes of data can be transferred over the

serial bus in one operation, but it is not possible to mix read

and write in one operation, because the type of operation is

determined at the beginning and cannot subsequently be

changed without starting a new operation.

For the NCT210, write operations contain either one or

two bytes, while read operations contain one byte.

To write data to one of the device data registers or read

data from it, the address pointer register must be set so that

the correct data register is addressed, data can then be written

into that register or read from it. The first byte of a write

operation always contains a valid address that is stored in the

address pointer register. If data is to be written to the device,

the write operation contains a second data byte that is written

to the register selected by the address pointer register.

This is illustrated in Figure 13. The device address is sent

over the bus followed by R/W set to 0. This is followed by

two data bytes. The first data byte is the address of the

internal data register to be written to, which is stored in the

address pointer register. The second data byte is the data to

be written to the internal data register.

Figure 13. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register

A6

SCLK

SDATA

A5

A4

A3

A2

A1

A0

D7

D6

D5

D4

D3

D2

D1

D0

ACK. BY

NCT210

START BY

MASTER

19

1

ACK. BY

NCT210

9

D7

D6

D5

D4

D3

D2

D1

D0

ACK. BY

NCT210

STOP BY

MASTER

1

9

SCLK (CONTINUED)

SDATA (CONTINUED)

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

ADDRESS POINTER REGISTER BYTE

FRAME 3

DATA BYTE

R/W

Figure 14. Writing to the Address Pointer Register Only

A6

SCLK

SDATA

A5

A4

A3

A2

A1

A0

D7

D6

D5

D4

D3

D2

D1

D0

ACK. BY

NCT210

STOP BY

MASTER

START BY

MASTER

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

ADDRESS POINTER REGISTER BYTE

1

1

9

ACK. BY

NCT210

9

R/W

Figure 15. Reading Data from a Previously Selected Register

A6

SCLK

SDATA

A5

A4

A3

A2

A1

A0

D7

D6

D5

D4

D3

D2

D1

D0

NO ACK. BY

MASTER

STOP BY

MASTER

START BY

MASTER

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

DATA BYTE FROM NCT210

1

1

9

ACK. BY

NCT210

9

R/W

When reading data from a register there are two

possibilities:

1. If the NCT210’s address pointer register value is

unknown or not the desired value, it is first

necessary to set it to the correct value before data

can be read from the desired data register. This is

done by performing a write to the NCT210 as

before, but only the data byte containing the

register read address is sent, because data is not to

be written to the register. This is shown in

Figure 14.

A read operation is then performed consisting of

the serial bus address, R/W bit set to 1, followed