AS7058 datasheet(63/199 Pages) AMSOSRAM

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AS7058

Functional description

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DS001077 • v2-00 • 2025-Sep-24

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7.10.3.4 I²C read

For reading data from the slave device, the master has to change the transfer direction. This

can be done either with a repeated START condition followed by the device-read address or

with a new transmission START followed by the device-read address when the bus is in an

IDLE state. The device-read address is always followed by the first register byte transmitted

from the slave. In Read mode, any number of subsequent register bytes can be read from the

slave. The word address is incremented internally.

Figure 55: I²C random read format

Random Read and Sequential Read are combined formats. The repeated START condition is

used to change the direction after the data transfer from the master.

The word address transfer is initiated with a START condition issued by the master while the

bus is idle. The START condition is followed by the device-write address and the word

address.

To change the data direction, a repeated START condition is issued on the first SCL pulse

after the acknowledge bit of the word address transfer. After the reception of the device-read

address, the slave becomes the transmitter. In this state, the slave transmits register data

located by the previously received word address vector. The master responds to the data byte

with a “not-acknowledge” and issues a STOP condition on the bus.

Figure 56: I²C sequential read format

Sequential Read is the extended form of Random Read, as more than one register-data byte is

subsequently transferred. In contrast to the Random Read, an acknowledge from the master is

the response for the transferred register-data bytes for a sequential read.

A Sr

data

RA++

A Sr

data 1

data 2

...

data n

RA++

AS7058 Datasheet(PDF) 63 Page - ams-OSRAM AG