programming nrf52840 fails during writing after a random amount of time

[michieldhont]

i have a custom board with an nrf52840, i use a J-link programmer to flash the chip with the nrf connector programmer app.

I am able to read the memory and erase the chip, however when i try to write any hex to the device it fails with an error. when using j-flash lite it also fails most of the time but the point where it fails is random and in rare cases it doesn't fail though this chance decreases as the hex size increases. The error J-flash reports is ERROR: Could not download file. and J-link commander is even less helpful with Error while programming flash: Programming failed.
the things i tried to flash are:
particle boron firmware
s140 softdevice
an arduino bootloader
all with the same result
i have measured the power supply on the board and it is 3.3v without any large dips
on a dev board with the same chip and everything connected in the same way it flashes successfully so i suspect a hardware issue.
any suggestions to where i could  look are welcome


the nrf connect log: https://pastebin.com/vqJjujn9

[Karl Ylvisaker]

Hello, 

I am able to read the memory and erase the chip, however when i try to write any hex to the device it fails with an error. when using j-flash lite it also fails most of the time but the point where it fails is random and in rare cases it doesn't fail though this chance decreases as the hex size increases.

on a dev board with the same chip and everything connected in the same way it flashes successfully so i suspect a hardware issue.

This makes me suspect a hardware issue as well. Which debugger are you using, and how is it connected to the SoC on the custom board? Please be as specific as possible.
Have you been able to successfully program your custom board previously? If so, is there any difference between the setups used then and now?

it also fails most of the time but the point where it fails is random and in rare cases it doesn't fail though this chance decreases as the hex size increases.

Erasing and writing takes significantly longer than just reading the memory, so this also points in the direction of a hardware issue. 

Best regards,
Karl