432 CHAPTER 16 Target interfaces and adapters
J-Link / J-Trace (UM08001) ©
2004-2017 SEGGER Microcontroller GmbH & Co. KG
16.4 9-pin JTAG/SWD connector
Some target boards only provide a 9-pin JTAG/
SWD connector for Cortex-M. For these devices
SEGGER provides a 20-pin -> 9-pin Cortex-M
adapter.
The following table lists the output of the 9-pin Cortex-M connector.
Pins 3 and 5 are GND pins connected to GND on the Cortex-M adapter. They should
also be connected to GND in the target system.
PIN SIGNAL TYPE Description
1VTref 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.
JTAG mode set input of target CPU. This pin should be
pulled up on the target. Typically connected to TMS of the
target CPU.
4SWCLK/TCKOutput
SWCLK: Clock signal to target CPU. It is recommended
that this pin is pulled to a defined state of the target
board. Typically connected to TCK of target CPU.
JTAG clock signal to target CPU.
6SWO/TDOInput
When using SWD, this pin is used as Serial Wire Output
trace port (optional, not required for SWD communica-
tion).
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.
8TDI Output
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. For CPUs
which do not provide TDI (SWD-only devices), this pin is
not used. J-Link will ignore the signal on this pin when
using SWD.
9NC (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.
Table 16.12: 9-pin JTAG/SWD pinout
12
34
56
78
910
VTref
GND
GND
---
NC
SWDIO / TMS
SWO / TDO
TDI
nRESET
SWCLK / TCK
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