KL05 MCU Reset PIN voltage errors

[thoomanwang]

Use the KL05 MCU, battery (3V), use 10K or  4.7K resistor pull-up Reset PIN, decoupling capacitor of 1uF.

Measuring voltage Reset PIN is only about 1.48V, then after Jlink, Jlink Commander can identify MCU, but Jlink LEDs constantly flashing red light.

Remove decoupling capacitance, measurements  the Reset PIN voltage is noly about 0.35V .

What is this problem? What do you do?

Previously used KL03 MCU have experienced the same problem

Circuit no problem, reviewed by Freescale technical support engineers

[mjbcswitzerland]

Hi

Could this be similar ? - KL05 reset line problem?

Remember that the RESET line is configurable in the Flash configuration. If the flash configuration disables it it will be a GPIO instead.

If you have loaded code, the code can also reprogram the function of the pin and drive it as an output.

In the case of the freedom boards there is a blog entry about the debugger flashing the red light, which I can't find at the moment, but I think that it was due to the program code loaded to it configuring something incorrectly (such as setting the clock too high which stopped it and also the debug connection working). In that case the debugger couldn't attach to the board any more (seen by the blinking red light since the KL05's watchdog keeps firing but the code repeating the error) - the solution was to load 'known good' code to the board via the USB-MSD loader and afterward the debugger would work again.

If not working on a board with an OpenSDA which can do this it will be up to the JLink to take over the control, which I would expect it to be able to do as long as the RESET has not be re-configured; in which case recovery may be more difficult (?).

Regards

Mark

[thoomanwang]

I'm using my own circuit board processing, not the FRDM.

Welded chips later (without writing any code) to directly measure Reset voltage (10K ohm pullup, 1uF capacitor decoupling) is around 1.5V, remove the decoupling capacitor measuring voltage is approximately 0.35V, which means MCU has been constantly repeated start, and now I want to erase the entire chip Flash, what should I do?