GPIO held high

[stefano]

Hi,

recently I experienced a strange behavior on the nRF51 chip, that is at a certain point some gpio lines remained held high, even if the firmware set them to low (both at init and during functioning). Even after a firmware update through DFU service these pins remained held high. Only after I switch off and on the my custom board, these pins restart behave normally.

Someone else had a similar problem? What could be the cause of this behavior? How to solve it?

Thank you.

[stefano]

30 GPIO are driving each one a FET transistor. also with a pull down of 100K. thus there is nothing from the electronic side pulling them up to high.

even during reprogramming the pins where not coming down. 5 pins had this behavior, the other moved normally. Ater OFF-ON all pins behaved normally again.

in the mean time however the driven solenoids burned as instead of 30% duty they got constant power....

the nrf51 chip is contained in the fujitsu module MBH7BLZ02 we acquired from Rutronik about 4 months ago.