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CoreSight™ 20 connector

The CoreSight™ 20 connector is a 20-way 1.27mm pitch box header which supports JTAG debug, Serial Wire Debug, SWO trace, and up to 4-bit wide continuous-mode TPIU trace.

To use CoreSight 20 connector with DSTREAM-ST, use the CoreSight 20 debug cable supplied in the box contents.

Warning

You must configure the pinout mode of the CoreSight 20 connector before using it.

If you do not configure the CoreSight 20 connector correctly, your DSTREAM-ST unit might not operate correctly. For example, if the pinout was configured for debug and trace, instead of debug only: the nTRST signal might terminate as if it was a TRACEDATA signal, which causes the nTRST signal to be asserted, and might cause a TAP reset when the DSTREAM-ST unit is connected.

To configure the pinout mode, use the Platform Configuration Editor (PCE) in Arm® Development Studio. In the PCE, select Debug Adapter, then select the Probe Configuration tab. In the configuration items table, set the DSTREAMCS20 configuration item to either:

  • 0: to use the connector in JTAG debug and trace mode.
  • 1: to use the connector in JTAG debug only mode.

For more information, see Configure your debug hardware unit for platform autodetection in the Arm Development Studio User Guide.

Figure 2-3 CoreSight 20 connector pinout


CoreSight™ 20 pinout tables

Pinout when DSTREAMCS20 is set to 0:

Table 2-4 Arm CoreSight 20 pinout table (DSTREAMCS20=0)

Pin Signal name   Pin Signal name
1 VTREF   2 TMS/SWDIO
3 GND   4 TCK/SWCLK
5 GND   6 TDO/SWO
7 Key (NC)   8 TDI
9 GND   10 nSRST
11 GND (1)   12 TRACECLK
13 GND (1)   14 TRACEDATA[0]
15 GND   16 TRACEDATA[1]
17 GND   18 TRACEDATA[2]
19 GND   20 TRACEDATA[3]

Pinout when DSTREAMCS20 is set to 1:

Table 2-5 Arm CoreSight 20 pinout table (DSTREAMCS20=1)

Pin Signal name   Pin Signal name
1 VTREF   2 TMS/SWDIO
3 GND   4 TCK/SWCLK
5 GND   6 TDO/SWO
7 Key (NC)   8 TDI
9 GND   10 nSRST
11 GND (1)   12 RTCK
13 GND (1)   14 SWO
15 GND   16 nTRST
17 GND   18 DBGRQ
19 GND   20 DBGACK
  1. Although these pins are typically grounded on the target board, the MIPI specification also allows them to carry power. If they are connected to a power rail (or rails) on the target board, these pins must also be AC-coupled to GND. To couple the pins to GND, use 100nF capacitors that are close to the connector.

Note

Pin 7 must be removed for compatibility with DSTREAM-ST and MIPI specifications.

Warning

Using a non-shrouded header on the target board can lead to short-circuits or signal contention. To ensure the correct polarity and position, Arm recommends that you use a fully shrouded box header.
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