WM8595 Datasheet, PDF (19/82 Pages) Wolfson Microelectronics plc – 24-bit 192kHz 2Vrms Multi-Channel CODEC

Production Data
WM8595
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
REGISTER READBACK
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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PD, Rev 4.2, January 2011
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