Transition from J-Link Edu to J-Link Mini Edu

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    • Transition from J-Link Edu to J-Link Mini Edu

      Hi there,

      We are looking at transitioning from our current teaching system of a Beaglebone Black -> TI-CTI-20 -> J-Link Edu to using a J-Link Mini Edu. According to J-Link Configurator V7.96b, I have the following hardware versions, J-Link Edu: V10.10, J-Link Edu Mini: V1.00.

      When I connect the J-Link Edu I can identify the Cortex-A8 in the AM3359 and connect to it. However, when replacing the J-Link Edu with the J-Link Mini Edu I receive an error that TDO is constantly high and I am unable to connect to the Cortex-A8. Please see attached images.

      I'm sure I am doing something daft, but if someone could help save me from myself I'd appreciate it.

      Kind regards,
      Hamish
      Images

      • J-Link_Configuration.png

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      • JLinkEduWorking.png

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      • JLinkMiniEduFailure.png

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    • Is the target a 3.3V one?
      If not, that’s the culprit, as the EDU Mini does not have level shifters and therefore only supports 3.3V debug signals.

      Another thing is TRST. Not sure if the AM33
      59 needs that pin…

      BR
      Alex
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    • Thanks so much for your reply Alex!

      The target is 3.3V luckily, so we are ok there.

      TRST is an issue though. Looking at the Beaglebone Black schematics, TRST, is wired to GND via a 4k7 resistor. The J-Link Edu is pulling TRST high during debugging, but our J-Link Edu Mini configuration had the TRST line disconnected. Pulling TRST to 3.3V allowed the J-Link Edu Mini to debug the AM3359. Yay! However, this needs to be disconnected briefly and reconnected again each time we wish to debug which isn't ideal.

      So we have a solution that will work for us, we have connected a 3.3V buffer input to the RST line and connected the output of the buffer to TRST (Actually using two inverters from an 74HC04 IC for now, but it is achieving the same thing.).

      Just a follow up question, if you have time. We were unable to directly connect TRST (Pin9) from the J-Link Edu Mini to TRST on the Beaglebone Black and have the J-Link Edu Mini pull the TRST line high, as we observe on the J-Link Edu. Is there a way we could replicate the behaviour of the J-Link Edu on the J-Link Edu Mini? Or is the TRST line unable to pull the Beaglebone Blacks TRST line high?

      Thanks so much for your help once again!