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SWO/SWV on LPC-Link2 with CMSIS-DAP?

Question asked by Bryan Cantrill on May 26, 2020
Latest reply on Jul 1, 2020 by Robert Boys

We have an LPC55S69 on an LPCXpresso556S9, and we are trying to use the built-in LPC-Link2 (an LPC4322) as a debugger.

 

Running the CMSIS-DAP firmware (v5.361) on the LPC-Link2, the probe reports that it has no SWO/SWV capabilities; rltool output:

 

> probestatus
Index = 1
Manufacturer = NXP Semiconductors
Description = LPC-LINK2 CMSIS-DAP V5.361
Serial Number = JSAQCQIQ
VID:PID = 1FC9:0090
Path = /dev/hidraw2

IsOpen = TRUE
WireInitialized = TRUE
WireProtocol = SWD
CoresConfigured = TRUE
PacketSize = 1024
Reference Count = 1
HasSWV = FALSE
HasETM = FALSE
HasJTAG = TRUE
HasSWD = TRUE
Probe Type = CMSIS-DAP

TAP = 0
Core = 0
CoreReferenceCount = 1
HighestPriority = 0
APID = 84770001
APIndex = 00
DPID = 6ba02477
CorePartNo = M33

AddrInc = 1024

Probe Reference Count = 1

However, we know that this is not the case: when running (for example) the lpcxpresso55s69_hello_world_swo via the MCUXpresso IDE (version 11.1.1_3241), we are able to get DWT data (and can see from a logic analyzer that there is DWT data on the SWO pin on the SWD header) -- and we know that the LPC55S69 can successfully generate TPIU-framed ITM data as well by using an external debugger via the SWD header.

 

Our questions: it appears that MCUXpresso is going through an interface other than CMSIS-DAP to enable SWO trace on the LPC-Link2; is this interface documented so we can use it through other CMSIS-DAP based tooling? Alternatively, is there LPC-Link2 firmware that correctly reflects its SWV capabilities via CMSIS-DAP?

 

With our thanks in advance for any help you can provide!

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