Still retained in debug mode nrf51822

[Satheeshkumar]

hi all

I am facing the issue that the chip still retains in debug mode. SWDCLK pin has connected to GND directly.

steps:

1. after flashed hex file, removed debugger from the chip and made a hard reset.

2. now my customized application has communicated with another device via UART(note: this is half-duplex communication and multiplexing UART line and power line to another device).

3.it again resuming debug mode and retain( ~1mA).

4.oftenly resetting the chip automatically.

NOTE:

1.SWDIO has connected to VDD with 10K resistor.

2.SWDCLK has connected to GND directly. I made strong GND on SWDCLK pin.

please help anyone.

thanks in advance

[Håkon Alseth]

Hi,

 

What is a hard reset? In order to exit debug mode, you need to either power cycle, or use "nrfjprog --pinreset".

Normally, the current consumption is 1.2mA when you're in debug mode. Are you seeing exactly 1.0 mA?

Does the current consumption change if you disconnect the UART connection going from the nRF to the external device?

 

Best regards,

Håkon

[Satheeshkumar]

yes exactly,  (~1.214mA) current has retained. at that time j-link was not connected 

[Turbo J]

Did you leave the UART connected? This can reverse-supply the chip via the RX pin, and could prevent the POR because VCC never drops low enough.

Remember that UART idle is HIGH.

[Satheeshkumar]

yes UART had removed and disabled UART module before sleep

[Håkon Alseth]

Does this occur on one specific module, or do several show this issue?

Just to confirm: A "hard reset" means that you are physically removing power to the nRF and applying it again afterwards?

 

You could also measure VDD_NRF after removing the battery to see if there's anything external trying to power up the nrf.

 

Best regards,

Håkon

[Satheeshkumar]

Hi Alseth,

sorry for late response. it was the pin reset by SWDIO/nReset pin. I have disabled all the software reset in my code.

I checked, there is no any external power up. we used bat42 diode to isolate the power to the nrf51 chip.

it is the very very huge issue for me. I have used RTC for the calendar, due to unnecessary reset,  the RTC also resetting the calendar value.

to avoid this issue, I have written the current calendar value in flash memory for every minute. even though, still persist the lagging of time.   

I am sure, the reset has happened by a chip which has changed to debug mode unnecessarily. please help me.