AnsweredAssumed Answered

Secure JTAG and reset: Vybrid stuck

Question asked by Emb edded on Apr 12, 2017
Latest reply on May 17, 2017 by Yuri Muhin

We are trying to get secure JTAG running on our devices with a Vybrid VF6xx. Establishing the connection, software download via Segger JFlash and issuing JTAG commands (halt, go etc.) via Segger JLink works as expected.

 

However, if the device is reset during the secure JTAG connection (via JTAG command or via SW reset), the device does not reboot properly. The device does the reset but then gets stuck with the PC somewhere around 0x6d54. As this address is before the starting address of our bootloader I assume it is part of the internal boot ROM.

 

The behavior is the same, if the JTAG connection is closed prior the reset. The only way to reboot the device again is a power cycle.

 

Is there a security feature that could prevent the device from booting properly after a reset occurred during or after a secure JTAG connection?

If so, can the device be configured to boot properly in such cases?

 

The E-Fuses for JTAG are set as follows:

* JTAG_SMODE 0x01 (secure JTAG)

* SEC_CONFIG 0x01

 

Thanks and best regards

Outcomes