WM8973-EV1M
w
Rev 1.0, February 2005
37
SOFTWARE INTERFACE
When using the WM8973-EV1B evaluation board with a DSP platform, the registers may be
set using the supplied software with a PC and parallel port cable as shown in Figure 29.
If the DSP is used to write to the WM8973 registers as well as supplying/receiving the audio
interface timing and data signals, it is recommended that twisted pair or shielded wires are
used to connect the DSP platform to the WM8973-EV1B. If the DSP supplies are set to the
same voltage as the DBVDD supplies of the WM8973, a direct connection can be made to
pin 6 (CSB), pin 7 (SDIN) and pin 8 (SCLK) of header strip J13 for 3-wire software mode as
shown in Figure 30. If the DSP is running at a higher voltage (e.g. +5V) than the WM8973,
the signals from the DSP platform should be connected to test points TP2 (CSB), TP4
(SDIN) and TP3 (SCLK). Connecting the higher voltage signals from the DSP to the test
points will level shift through the transistors down to the same level as the DBVDD supply as
shown in Figure 31. This will ensure that the WM8973 input CMOS thresholds (i.e. Logic
High (min) = DBVDDx0.7; Logic Low (max) = DBVDDx0.3) are met and the device will not be
damaged.
The same connections apply for controlling the WM8973 via 2-wire software mode (i.e. only
pin 7 (SDIN) and pin 8 (SCLK) of header strip J13 are used). Pin 6 (CSB) can be pulled low
on the board if device address 0011010 [0x34h] is required or pulled high address 0011011
[0x36h] is required.
CONNECTION DIAGRAMS
Figure 29 DSP Connection with PC Control using Wolfson Software
Summary of Contents for WM8973-EV1B
Page 1: ...WM8973 EV1M Evaluation Board User Handbook Rev 1 0...
Page 3: ...WM8973 EV1M w Rev 1 0 February 2005 3 EVALUATION SUPPORT 44 IMPORTANT NOTICE 45 ADDRESS 45...
Page 21: ...WM8973 EV1M w Rev 1 0 February 2005 21 SCHEMATIC LAYOUT Figure 13 Functional Diagram...
Page 22: ...WM8973 EV1M w Rev 1 0 February 2005 22 Figure 14 Digital Input...
Page 23: ...WM8973 EV1M w Rev 1 0 February 2005 23 Figure 15 Software Control...
Page 24: ...WM8973 EV1M w Rev 1 0 February 2005 24 Figure 16 Level Shift...
Page 25: ...WM8973 EV1M w Rev 1 0 February 2005 25 Figure 17 Analogue Input...
Page 26: ...WM8973 EV1M w Rev 1 0 February 2005 26 Figure 18 WM8973...
Page 27: ...WM8973 EV1M w Rev 1 0 February 2005 27 Figure 19 Analogue Output...
Page 28: ...WM8973 EV1M w Rev 1 0 February 2005 28 Figure 20 Power...
Page 29: ...WM8973 EV1M w Rev 1 0 February 2005 29 WM8973 EV1B PCB LAYOUT Figure 21 Top Layer Silkscreen...
Page 30: ...WM8973 EV1M w Rev 1 0 February 2005 30 Figure 22 Top Layer...
Page 31: ...WM8973 EV1M w Rev 1 0 February 2005 31 Figure 23 Bottom Layer...
Page 32: ...WM8973 EV1M w Rev 1 0 February 2005 32 Figure 24 Bottom Layer Silkscreen...