Power-on-reset Circuit for MBN52832 (nRF52832)

[HanCatNguyen]

I want to reset the MBN52832 right after power off then back on so that I will only need a power switch for my custom board (instead of also adding a reset button). However, when I tried to make a power-on-reset circuit with just a 1uF (or 10uF) capacitor and a 10KOhm resistor connecting like below, the chip doesn't reset when I switch the power back on. Is there something wrong with my circuit? Any suggestions on any other ways I can get the automatic reset upon powering off then back on?

[HanCatNguyen]

Is the requirement you're referring to "A step increase in supply voltage of 300 mV or more, with rise time of 300 ms or less, within the valid supply range, may result in a system reset."? Then yes, my DVDD powering up satisfies that, but the chip doesn't reset. Is it supposed to automatically reset when powering on (without connecting nRESET pin to anything)?

The chip does boot up (but doesn't reset) when I turn the power back on. My code is based on the ble_app_uart example of the nRF5 SDK with added SPI communication. That example code had the same problem that the chip doesn't BLE re-advertise after powering off then back on (without resetting). My ultimate goal is to be able to BLE re-advertise after powering on without the need of pressing a RESET button. Any suggestions?

[ketiljo]

The POR will always hold the device in reset after power up. Why do think it's not reset? Do you have any pins that are high before the power is applied?

Adding a very large cap to the reset pin does not solve this, remove this.

[HanCatNguyen]

I think it doesn't reset because it didn't BLE re-advertise after powering off then back on. The LED pin for indicating BLE status (P0.17) went HIGH after powering up instead of blinking to indicate BLE advertising. I have tried without anything connected to the reset pin, and same problem. How should I fix this?

[ketiljo]

Since the LED is lit, it indicates that POR is working since the pin is set as an high output. Hva you tried to debug to see what's going on after reset? Doing another reset is not a good solution here, you need to find out why it fails after power on.