DIO1408

Version 1.0, Jul 2025

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© 2025 Dioo Microcircuits Co., Ltd. Jiangsu

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8.2.3. Writing and reading operation

Accessing a particular register on the DIO1408 needs to write the appropriate value to the pointer register first.

After the address byte is sent with the data direction bit LOW and DIO1408 generates an acknowledge bit, the

master sends the value for the pointer register. Then the master can write to the corresponding data register on

the DIO1408. So every writing operation to the DIO1408 requires sending a value for the pointer register first.

When reading from the DIO1408, the value for the pointer register sent by last writing operation is stored and is

used to determine which data register is read by a reading operation. The DIO1408 stores the value of the

pointer register until it is changed by a writing operation, so the same data register can be repeatedly read by

only sending the pointer register bytes once. If a reading operation from another data register is desired, the new

value must be written to the pointer register. A writing operation to the pointer register can be performed first

without sending other data to the data register. The master can then generate a new START condition and

initiate the read command to read from another data register.

Figure 6. Two-wire write word format

Note:

(1) The value of A0 and A1 are determined by the A0 pin.

(2) Master should leave SDA high to terminate a single-byte reading operation.

(3) Master should leave SDA high to terminate a two-byte reading operation.

(4) S: Start, A: ACK, P: Stop.

Figure 7. Two-wire read word format