topic Re: MK22x JTAG Interface in Kinetis Microcontrollers

MK22x JTAG Interface

zachaeva — Sat, 31 Oct 2020 00:46:51 GMT

I am using a MK22FN512VLH12 MCU (which is the same used on the K22F freedom development boards).

I am attempting to add the JTAG/SWD debug header onto my schematic and the reference guide/datasheet are not clear on whether there should be pull ups or capacitors present on the JTAG header.

The MK20x product series asks for a 0.1uF capacitor on pin 1 (VCC) of the JTAG interface as well as a 10k pullup on the TMS line, the MK22x product series does not mention these.

In addition, is a pullup or down needed on PTA5 the tRST (not the MCU chip reset, but the jtag reset)? There is no mention of if one is present.

Schematic attached.

Re: MK22x JTAG Interface

myke_predko — Sun, 01 Nov 2020 15:57:23 GMT

Hi @zachaeva

Here is the circuitry that I use for my MK22FN1M0AVMD12 (which should be the same as your part) - Instead of a 20 pin JTAG connector, I use the 10 pin Segger Needle Probe connector.

Obviously, I don't bother with the capacitor on the JTAG connector's VCC line. I do have a pull up on the TMS line - but you might want to check the value. Finally, I don't bother with the JTAG tRST line with the K22.

Good luck!

myke

Re: MK22x JTAG Interface

kerryzhou — Mon, 02 Nov 2020 05:55:24 GMT

Hi zachaeva,

Check the kinetis quick guider:

https://www.nxp.com/webapp/Download?colCode=KQRUG

NMI need external 4.7K to 10K pull up resistor.

Reset pin need to add 4.7K to 10K pull up resistor, and 0.1uf capacitor to ground.

Wish it helps you!

If you still have questions about it, please kindly let me know!

Best Regards,

Kerry

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