sdti-005
0100
1100
Ad
[7:4]
Ad
[3:0]
Da
[15:12]
Da
[11:8]
Da
[7:4]
Da
[3:0]
SDTI_CLK
SDTI_TXD
sdti-006
0100
1100
Da
[7:4]
Da
[3:0]
SDTI_CLK
SDTI_TXD
Public Version
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SDTI Module
Trace receivers sample trace data on each clock edge. The trace clock (SDTI_CLK) starts with a falling
edge. The sdti_clk signal is forced high until the first data value is available.
Serial interface operates in clock stop mode; when there is no data available, the clock stops. SDTI_CLK
is not a free-running clock.
To support older trace receivers, serial interface can be placed into single-edge mode where data is
captured with the falling edge of the trace clock (
[4] SINGLEEDGE = 1).
shows the SDTI dual-edge serial interface waveform.
Figure 27-12. Dual-Edge Clock Waveform
shows the SDTI single-edge serial interface waveform.
Figure 27-13. Single-Edge Clock Waveform
The SDTI serial interface is configurable to support one, two, and four data bits operation. Depending on
the configuration, trace data is exported on sdti_txd[0], sdti_txd[1:0], or sdti_txd[3:0].
Serial clock frequency is selected in the SDTI serial configuration register (the
[3:0]
SDTISCLKRATE bit field). Programmers must select the correct serial frequency (choose division factor)
based on the functional clock frequency.
27.3.2.3 SDTI Data Format
summarizes the message types.
Table 27-27. SDTI CPU Software Messages
Type
Identification
CPU1 timestamped message
001D DAtt
CPU1 message
010D DA00
CPU2 timestamped message
011D DAtt
CPU2 message
110D DA00
3609
SWPU177N – December 2009 – Revised November 2010
Debug and Emulation
Copyright © 2009–2010, Texas Instruments Incorporated