WM8215

Production Data

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PD, Rev 4.3, September 2012

21

SERIAL INTERFACE: REGISTER WRITE

Figure 16 shows register writing in serial mode. Three pins, SCK, SDI and SEN are used. A six-bit

address (a5, 0, a3, a2, a1, a0) is clocked in through SDI, MSB first, followed by an eight-bit data word

(b7, b6, b5, b4, b3, b2, b1, b0), also MSB first. Setting address bit a4 to 0 indicates that the operation

is a register write. Each bit is latched on the rising edge of SCK. When the data has been shifted into

the device, a pulse is applied to SEN to transfer the data to the appropriate internal register.

SCK

SEN

SDI

a5

0

a3

a2a1a0b7

b6b5b4b3

b2b1b0

Address

Data Word

Figure 16 Serial Interface Register Write

A software reset is carried out by writing to Address “000100” with any value of data, (i.e. Data Word

= XXXXXXXX).

SERIAL INTERFACE: REGISTER READ-BACK

Figure 17 shows register read-back in serial mode. Read-back is initiated by writing to the serial bus

as described above but with address bit a4 set to 1, followed by an 8-bit dummy data word. Writing

address (a5, 1, a3, a2, a1, a0) will cause the contents (d7, d6, d5, d4, d3, d2, d1, d0) of

corresponding register (a5, 0, a3, a2, a1, a0) to be output MSB first on pin SDO (on the falling edge of

SCK). Note that pin SDO is shared with an output pin, OP[9], therefore OEB should always be held

low and the OPD register bit should be set low when register read-back data is expected on this pin.

The next word may be read in to SDI while the previous word is still being output on SDO.

Figure 17 Serial Interface Register Read-back