A week ago, I decided to put 5x2 header on FRDM to use it as a general debugger for my custom KL25Z board. To be honest, I am a software engineer, who is not good at SMD manual soldering.
After soldering I found there are short-circuit among them by Multimeter. So I have to remove the header again.
But after doing all of these messy things, I found my FRDM doesn't work anymore.
Sometimes it blinks.
The OS always prompts it can not communicate with target MCU. Finally I found the RST pin from OpenSDA K20 to target KL25Z is almost zero (about 0.7V). I pull up the RST with a jumper. The user application runs well. But since the RST pin can not controlled by OpenSDA, its complains all the time. Furthermore, since I am using jumper to enforce pulling up, so the voltage is not stable, which can be checked by the brightness of LEDs.
I checked the circuit, I found the SWD debugger interface are all protected by buffer IC, with only exception: RST pin.
Is RST pin of K20 skewed up? Any ideas? Otherwise I have to throw it away and buy a new FRDM. Still I am afraid of soldering the SMD header. Why not populating SMD out of fab?