19-pin JTAG/SWD and Trace Connector

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This article describes the 19-pin JTAG/SWD and Trace Connector, available on all J-Trace Pro.

Pinout

J-Link 19-Pin Cortex-M Adapter / J-Trace 19-pin pinout


J-Trace provides a JTAG / SWD + Trace connector. This connector is a 19-pin connector (0.05" / 1.27mm). It connects to the target via an 1-1 cable.
The following table lists the J-Link / J-Trace SWD pinout.

PIN SIGNAL TYPE Description
1 VTref Input This is the target reference voltage.
It is used to check if the target has power, to create the logic-level reference for the input comparators and to control the output logic levels to the target. It is normally fed from VDD of the target board and must not have a series resistor.
2 SWDIO / TMS I/O / Output
  • SWDIO: (Single) bi-directional data pin.
  • TMS: JTAG mode set input of target CPU.
    This pin should be pulled up on the target. Typically connected to TMS of the target CPU.
4 SWCLK / TCK Output
  • SWCLK: Clock signal to target CPU.
  • TCK: JTAG clock signal to target CPU.
It is recommended that this pin is pulled to a defined state of the target board.
6 SWO / TDO Input
  • SWO: Serial Wire Output trace port. (Optional, not required for SWD communication)
  • JTAG data output from target CPU. Typically connected to TDO of the target CPU.
--- --- --- This pin (normally pin 7) is not existent on the 19-pin JTAG/SWD and Trace connector.
8 NC / TDI NC / Output
  • SWD: Not used. J-Link will ignore the signal on this pin when using SWD.
  • TDI: JTAG data input of target CPU. It is recommended that this pin is pulled to a defined state on the target board. Typically connected to TDI of the target CPU.
9 Not connected (TRST) NC By default, TRST is not connected, but the Cortex-M Adapter comes with a solder bridge (NR1) which allows TRST to be connected to pin 9 of the Cortex-M adapter.
10 nRESET I/O Target CPU reset signal. Typically connected to the RESET pin of the target CPU, which is typically called "nRST", "nRESET" or "RESET". This signal is an active low signal.
11 5V-Supply Output This pin can be used to supply power to the target hardware.
Older J-Links may not be able to supply power on this pin. For more information about how to enable/disable the power supply, please refer to Target power supply. If you do not plan to supply power to the target via this pin it is recommended to connect it to GND.
12 TRACECLK Input Input trace clock.
Trace clock = 1/2 CPU clock in most cases.
13 5V-Supply Output This pin can be used to supply power to the target hardware.
Older J-Links may not be able to supply power on this pin. For more information about how to enable/disable the power supply, please refer to Target power supply. If you do not plan to supply power to the target via this pin it is recommended to connect it to GND.
14 TRACEDATA[0] Input Input Trace data pin 0.
16 TRACEDATA[1] Input Input Trace data pin 1.
18 TRACEDATA[2] Input Input Trace data pin 2.
20 TRACEDATA[3] Input Input Trace data pin 3.
3, 5, 15, 17, 19 GND Ground GND pins connected to GND in J-Link.
They should also be connected to GND in the target system.

Connecting the target board

J-Trace connects to the target board via a 19-pin trace cable. Alternatively J-Trace can be connected via the 20-pin J-Link Connector.

Note:

Never connect 19- & 20-pin cable at the same time because this may lead to unstable debug and trace connections.

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