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KE04 SWD Interface Question

Question asked by JIM MORRIS on Jun 21, 2017
Latest reply on Jun 25, 2017 by Kerry Zhou

I just finished a design using a Kinetis KE04 series part (MKE04Z8VTG4), and came across this footnote in section 9.2 (Debug port pin descriptions) of the KE04 reference manual for this part:

 

1. The pad library of this device does not support on-chip pull down; the SWD_CLK pin supports only pulp controlled by PTAPE0, external pulldown resistor is required to fully support the SWD protocol.

 

Yet I have looked at the schematics for the FRDM-KE04Z board with the 24 pin version of this chip on it, and do not see any pulldown in the circuit on the SWD_CLK line of the device.

 

Can anyone comment on this, as I have a completed set of gerber files for my PCB, but don't want to pull the trigger on an order until I know whether I need to add a pulldown resistor on this signal. Right now I just have RESET (PTA5), SWD_DIO (PTA4), and SWD_CLK (PTA0) going to the respective pins on a Mini-10 ARM header, along with GND and VCC.

 

Thanks!

Jim

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