WM8595 datasheet(19/82 Pages) WOLFSON

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Production Data

WM8595

PD, Rev 4.2, January 2011

AUTO-INCREMENT REGISTER WRITE

It is possible to write to multiple consecutive registers using the auto-increment feature. When

AUTO_INC is set, the register write protocol follows the method shown in Figure 8

. As with normal register writes, the controller indicates the start of data transfer with a high to low

transition on SDA while SCLK remains high, and all devices on the bus receive the device address.

When the WM8595 has acknowledged a correct address, the controller sends the first byte of control

data (A6 to A0, i.e. the WM8595 initial register address). The WM8595 then acknowledges the first

control data byte by pulling SDA low for one SCLK pulse. The controller then sends a byte of register

data. The WM8595 acknowledges the first byte of register data, auto-increments the register address

to be written to, and waits for the next byte of register data. Subsequent bytes of register data can be

written to consecutive registers of the WM8595 without setting up the device and register address.

The transfer of data is complete when there is a low to high transition on SDA while SCLK is high.

Figure 8 2-Wire Auto-Increment Register Write

The WM8595 allows readback of all registers with data output on the bidirectional SDA pin. The

protocol is similar to that used to write to the device. The controller will issue the device address

followed by a write bit, and the register index will then be passed to the WM8595.

At this point the controller will issue a repeated start condition and resend the device address along

with a read bit. The WM8595 will acknowledge this and the WM8595 will become a slave transmitter.

The WM8595 will place the data from the indexed register onto SDA MSB first. When the controller

receives the first byte of data, it acknowledges it. When the controller receives the second and final

byte of data it will not acknowledge receipt of the data indicating that it will resume master transmitter

control of SDA. The controller will then issue a stop command completing the read cycle.

Figure 9 2-wire Read Protocol

AUTO-INCREMENT REGISTER READBACK

It is possible to read from multiple consecutive registers in continuous readback mode. Continuous

readback mode is selected by setting AUTO_INC. In continuous readback mode, the WM8595 will

return the indexed register first, followed by consecutive registers in increasing index order until the

controller issues a stop sequence.

Figure 10 2-Wire Auto-Increment Register Readback

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