Connecting Multiple J-Links / J-Traces To Your Pc; How Does It Work - Segger J-Link User Manual

5.6

Connecting multiple J-Links / J-Traces to your PC

In general, it is possible to have an unlimited number of J-Links / J-Traces connected
to the same PC. Current J-Link models are already factory-configured to be used in a
multi-J-Link environment, older J-Links can be re-configured to use them in a multi-
J-link environment.
5.6.1

How does it work?

USB devices are identified by the OS by their product id, vendor id and serial number.
The serial number reported by current J-Links is a unique number which allows to
have an almost unlimited number of J-Links connected to the same host at the same
time.
The sketch below shows a host, running two application programs. Each application-
communicates with one CPU core via a separate J-Link.
Application
Target hardware 1
Older J-Links / J-Traces all reported the same serial number which made it necessary
to configure them for USB0-3 if multiple J-Link should be connected to the same PC
in parallel.
For these J-Links, we recommend to re-configure them to use the new enumeration
method (report real serial number).
Re-configuration can be done by using the J-Link Configurator, which is part of the J-
Link software and documentation package.
Re-configuring J-Link to use the new method does not have any bad side-effects on
the current debug environment. Usually the user does not see any difference as long
as only one emulator is connected.
J-Link / J-Trace (UM08001)
Host (PC)
Instance 1
USB
J-Link
1
JTAG
CPU0
Target hardware 2
Application
Instance 2
USB
J-Link
2
JTAG
CPU1
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