Hi,
My company has a product that is in production using the nRF5340 SOC. We noted this morning that the product would boot and application code even if the nRF5340's reset pin was held low during the device's power on and boot sequence. This is unexpected behavior and it should be noted that the same device can be held in reset indefinitely if reset is pulled low following the power on and boot sequence.
I confirmed seeing the same behavior on an nRF5340 development kit, PCA10095 version 2.0.1:
- I programmed the kit using the nRF Connect SDK v2.4.2 BLINKY code example and verified normal operation and reset of the development kit.
- The nRF5340 nRESET net was isolated from U6 and U5 by opening solder jumpers SB42 and SB56.
- nRESET was then connected to ground through a test lead.
- When power is applied to the board with nRESET grounded, the nRF5340 will boot, the application will run and the LED blinks.
- If nRESET is disconnected and then re-connected to ground, the LED will extinguish and stay extinguished as long as nRESET is connected to ground.
The image below shows the LED blink voltage cycling even though reset is held low throughout and after POR.
Is application code running while nRESET is being held low through POR the expected behavior of the nRF5340?
