AnsweredAssumed Answered

KL05 reset line problem?

Question asked by Frost on Aug 6, 2013
Latest reply on Aug 9, 2013 by TurboMan

I have a KL05Z32VLF4, 48pin LQFP package MCU. I've used the freedom boards, both KL25 and KL05 successfully with SDA and SWD using a segger j-link.

 

So, I have a custom board with the KL05Z32VLF4 on, the reset line is pulled to 3v3 with a 10K resistor, there is a 100nF cap to ground, and a switch across the cap. Due to an oversight I didn't put a series resistor in there, so had to remove the cap for the JTAG to connect up ok. The JLink connects and can debug a program, but the reset line is low when the JLink is not connected.

 

The 10K resistor manages to pull the reset line up to 0.3V without the cap, but I measured 1.5V with the 100nF in. As I write this, looking at the KL05 schematic, I can see a 1uF in the circuit, so I'm off to try a larger value of cap; could this be it?

 

Why is the reset line so low, has anyone else had this problem? What's wrong with my reset circuitry (apart from missing series resistor perhaps) I can find no shorts / open circuits in this area. Chip operates ok otherwise when reset is driven by JLink.

 

Thanks for any tips.

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