Hello Charles T
When power is initially applied to the MCU or when the supply voltage drops below the power-on reset re-arm voltage level (VPOR), the POR circuit causes a POR reset condition. As the supply voltage rises, the LVD circuit holds the MCU in reset until the supply has risen above the LVD low threshold (VLVDL).
If no external circuits are added then the reset may have issues. You can add a pull up circuit like this one with the resister and capacitor:
It would be helpful if you attach your schematic so I can help you better.
Let me know if this helps.
Best regards,
Omar
Hello Omar,
Thanks a lot for your kind and detailed reply.
It's checked that the VCC is always 3.28v after Power on. So the case here is not like LVD and POR mentioned 5.2.2
As external circuits, I put my schematics below for your reference.
Two Reset Circuits to check which one is OK. To do that, a Jumper link will be put on J5.
Neither did work when a Jumper link was put on. I meant voltage at /RST is 0.1v (link Pin 1 and Pin 2 of J5 ) after Power ON.Reset is 0v when Manual reset key press and 1v when reset key release (link Pin 1 and Pin 3 of J5) . by the way, Pin 1 in schematics here is in the middle position of J5 at PCB. If without the jumper link, both Pin 2 and Pin 3 of J5 is 3.28v after Power on, and /RST is still logic low. I'm wondering if mass erase ever implementation make this kind of situation.
a Pullup resistor is at PTA4, which can be seen from below circuitry. and clock as well.
Below is JTAG connection.
Below is VDD and VSS connection.
That's it. the MK10DX128VLL7 soldering orientation and related PINs (VCC, GND, Rest, Oscillator) soldering quality are all checked. no shortage no void soldering.
So strange. And I will check the signal with Oscilloscope later on today.
Thanks and Best regards
Charles
Thanks Omar!
the external reset worked based on the oscilloscope but the MCU was not reset correctly when the RESET pin of MCU is connected to the external reset.
without a jumper, the signal at PIN 3 of J5 is like this followed by a manual reset.
with a jumper. the signal at PIN 3 of J5 is like this
that's because the reset pin of MCU with no any jumper waveform is like this. That indicated MCU was not reset correctly.
The reset chip output waveform is like this if with no jumper, which indicated the reset chip works.
the waveform changed as the following one after putting jumper on.
All the above waveform proved the MCU was not reset successfully.
Furthermore, it's found Crystal Oscillator didn't work. Saying so there was no waveform to be detected at PIN 28 and PIN29 of MCU or say two pins of the Crystal Oscillator X2.
Neither was it after C24 C16 and R22 removed. It's checked no shortage to this two pins. And MCU orientation is correct as below.
I'm going to solder a known good Crystal Oscillator. if still failed, I may solder another MCU which does take time. Again, I'm wondering if this is due to ever mass erase operation to MCU.
Thanks and regards,
Charles
