WM8750-EV1M
To operate the WM8750 in 2-wire mode, jumper switch SW4 must be set so that pins 2 and
3 are SHORT. The 2-wire serial interface becomes active on pins 31(SDIN) and 32(SCLK).
The serial interface on the board can be connected to a PC via the printer port or any other
standard parallel port. Note:
a bi-directional parallel port is required for 2-wire
operation1. The 2-wire data and clock lines may also be connected to the board via the test
points TP4 (SDIN) and TP3 (SCLK).
When used in 2-wire mode, the WM8750 has two possible addresses (0011010 [0x34h] or
0011011 [0x36h]) that are selectable by pulling CSB low or high. If connecting a probe to the
Test Points it must be noted that the CSB line is pulled high on the WM8750 evaluation
board selecting address 0011011. CSB must be pulled low or driven low through the software
writes if address 0011010 is used (as is done in the WM8750-EV1S software provided).
ACK
ACK
ACK
DATA B15-8
R ADDR
R/W
DATA B7-0
SDIN
SCLK
START
STOP
Figure 3 2-Wire Serial Interface
1
Note: If the 2-wire mode does not operate as expected, the likely cause is the configuration
of the parallel port interface mode. Check that the port is configured for bi-directional
communication. Most PCs allow the parallel port to be configured in the BIOS settings during
initial PC power up.
Rev 2.0, February 2005
11
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
