Doubt about KwikStik j-link usage...

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Doubt about KwikStik j-link usage...

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EthernetHelp
Contributor II

Hi, i want to use the KwikStik j-link to program an externa Kinetis. What circuit should i add to create a proper connection? I was looking at the kwikstik schematic, and the signals that are connected to the header, are connected directly to the onboard kinetis.. 

 

On the kwikstick schematic there is a signal named: JTAG_EZB_CS_b

 

I am not familiar with this signal.. should i connect it or not? If yes how?

 

Thank you!

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bikenomad
Contributor III

Ethernet Help wrote:
On the kwikstick schematic there is a signal named: JTAG_EZB_CS_b

 

I am not familiar with this signal.. should i connect it or not? If yes how?




As far as I can tell, that's not used by the J-Link.

 

But note that due to a design error, you can't debug external processors without a circuit change.

 

The problem is that with the ON/OFF switch in the OFF position, the K40 is not powered. Which isn't a problem for the JTAG lines, as they're 5-V tolerant and so don't interfere when the K40 is not powered.

 

However, the RESET line is protected by an internal diode to the K40's VCC line.

 

So you can't pull RESET high with the on-board J-LINK without adding a diode in series with the K40's RESET line (anode to K40 pin 74, and remove R113 (there is an internal pullup on /RESET in the K40).

 

As they say, "if it hasn't been tested, it doesn't work".

 

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Mr_Honey
Contributor I

Thank you bikenomad, I disconnected power supply according to errata documentation (chipbead F5) and I disconnected RESET line temporally (I don't have diode small enough to fit between pin and via at the moment). It is working now. I've tried it with TWR K60 external target.

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