Freedom Board: How can I access the openSDA circuit K20 Cortex-M4 core via JTAG?

[qiaoy]

Noticed the OPENSDA circuit has the dedicated SWD/JTAG interface on board for the K20DX128. I'm thinking I may use this board for both KL25 and K20 development.

I tried to connect with JTAG then directly debug the openSDA code.

But I failed in JTAG connection with the K20 onboard. The JTAG can't find the K20 core. I double checked the connection. Shall be OK as I used K20 before in other projects.

Did you guys ever try this on Freedom board?

[rogerzhong · Accepted solution]

I guess the K20 would be secured by the manufacturer, but, even so, a JTAG tool(e.g. J-Link) can aslo detect the K20 core, and recognize the core ID. You can aslo implement a mass erase command by using a JTAG tool if the mass erase is dot disabled through FSEC[MEEN]; ortherwise, you would give up your idea to do so, because the chip may be permanently secured, and can never be accessed from any external sources. If the mass erase command can be accepted, it means you will damage the flash-resident USB mass-storage device (MSD) bootloader, and the OpenSDA and MSD Flash programmer application can never be booted, Furthermore, it can not be recovered by yourself.

Maybe, you'd better first refer to the user manual of FRDM-KL25Z borad, and know the security feature of K20's flash.

If you still decide to make a try, you pretty much do so at your own risk.

[pgo]

Dear Yu,

I believe the K20 on the Freedom board is both secured and mass erase disabled.  I do not believe you will be able to use it.

See this discussion:

Use removed MK20 part from freedom board

bye