Cannot program MK64FN1M0M12. Reset problem.

[rothkarl]

Hello everyone!

I have just produced a board which uses a MK64FN1M0VLQ12 chip.

The problem is that the chip's reset pin stays low after POR, and I cannot figure out how could I achive to pull its pin high.

The power supply of the chip seems to be ok, the reset pin is tighted through 1K resisitor towards positive rail, and through 100 nF cap to ground.

I am trying to probram my chip using FRDM-K64F board, but as soon I plug its SWD socket, the programmer's reset LED turns on, signing that the common reset line is low. So at this point I have no chance to program the chip.

I think I can rule out systematic hardware failure, the reset pin is not shorted toward ground, the power supplying shall be fine.

My question is, what can lead for this chip to hold its reset pin low?

Some additional info:

Chip is supplied from 3.3 V LDO. I have tried decreasing power up slew rate with a serial 33 Ohm and parallel 20 uF cap. But it doesn't help at all.

The Vregin and vout33 pins tighted through 10 k resistor to ground.

In a previous design this power scheme was used, and it worked.

I am looking forward for some help from NXP support team as well!

Thank you in advance!

[rothkarl]

It seems like the problem became solved. I have decided to put two 33 ohm resistors in series with data and clock line, and Voila now it works :smileyhappy:

The problem is that the FRDM-K64F demo board doesnt have serial terminating resistors on data and clock lines, which make almost impossible to probram an external chip with a longer cable,

Lesson learned.

Thank you for your help, I really appreciate it!

[petertsipouras]

Correction, the VLQ12 package has the NMI on pin 54, sorry.

[petertsipouras]

We have a 10K pullup on pin 38 (NMI). Also 22K pullup with 4.7uF on reset pin.

[daveanglin]

Make sure NMI pin is high.

[fangli]

Hi,

Is the reset signal oscillating?  Does the board you would like to program is an erased one? If yes,it maybe due to the watchdog timer is enabled and this will periodically reset the board.

[rothkarl]

The chip I am trying to program shall be completely clean. I have not managed to program it previously, so maybe the reset pin is oscillating.

Question is what could I do in case SWD cannot program the chip because this reset bouncing?

[rothkarl]

Update:

I have forgotten to connect EZP_CS pin, so I have connected it to Vdd. Now the symptom is that Reset pin is released after reset, but SWD cannot see the target board.

When I am trying  to program the board, I can see the Reset LED blinking, meaning that the MCU not holding its reset pin low.

The error I receive is "Target board not connected". Any idea?