AP72202

Document number: DS46304 Rev. 1 - 2

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May 2024

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AP72202

Application Information (continued)

Reading from a Single Register

The I2C master device reads one byte of data from AP72202. The read byte protocol is as follows:

1.

The master sends a START condition.

2.

The master sends the 7-bit slave address followed by a write bit (R/nW = 0).

3.

The addressed slave sends an ACK bit by pulling SDA low.

4.

The master sends an 8-bit register pointer.

5.

The slave acknowledges the register pointer.

6.

The master sends a REPEATED START condition.

7.

The master sends the 7-bit slave address followed by a read bit (R/nW = 1).

8.

The addressed slave sends an ACK bit by pulling SDA low.

9.

The addressed slave places 8 bits of data on the bus from the register specified by the register pointer.

10. The master issues a nACK.

11. The master sends a STOP condition or a REPEATED START condition.

Figure 9. Reading from a Single Register X

Reading from a Sequential Register

Figure 10 below shows the protocol for reading from sequential registers. This protocol is similar to the read byte protocol except the master issues

an ACK to signal the slave that it wants more data.

The slave’s register pointer will auto-increment by one after each byte sent. When the master

has all the data it requires, it issues a nACK and a STOP to end the transmission. The continuous read from sequential registers protocol is as

follows:

1.

The master sends a START condition.

2.

The master sends the 7-bit slave address followed by a write bit (R/nW = 0).

3.

The addressed slave sends an ACK bit pulling SDA low.

4.

The master sends an 8-bit register pointer.

5.

The slave acknowledges the register pointer.

6.

The master sends a REPEATED START condition.

7.

The master sends the 7-bit slave address followed by a read bit (R/nW = 1).

8.

The addressed slave sends an ACK bit by pulling SDA low.

9.

The addressed slave places 8-bits of data on the bus from the register specified by the register pointer.

10. The master issues an ACK signaling the slave that it wishes to receive more data.

11. Steps 9 to 10 are repeated as many times as the master requires.

12. Following the last byte of data, the master must issue a nACK to signal that it wishes to stop receiving data.

13. The master sends a STOP condition or a REPEATED START condition.

Figure 10. Reading Continuously from Sequential Registers X to N

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