Serial Connectivity and Serial DFU - High Current Draw - nRF51822

[jpreston]

I have combined Nordic's serial connectivity code and Nordic's serial DFU example.

Upon initial powerup, the nRF51822 draws an expected amount of current (~600uA). When issuing the system off command via serial, the current draw drops to about 0.5uA, which is to be expected.

The issue occurs when waking the nRF51822 via external interrupt. When I do that, the chip wakes up but starts drawing about 1800uA. Issuing the system off command drops it to about 1200uA. This current draw corresponds to what I see when the debug interface is active (i.e. just after programming the chip without a power cycle).

I have verified that the nRF51 is resetting because I have the DFU code send a string out the UART so the main processor can know it started. I've also verified that the application starts running after waking up from an external interrupt.

I'll also add that I don't see this issue unless I program the bootloader. The Softdevice and connectivity code show expected current draw all the time when the bootloader is not programmed.

Any advice?

[Hung Bui]

Hi Jpreston, If you want to use UART to send a byte, I would suggest you to use the app_uart directly, and use an event handler to catch when the byte is sent before closing app uart, instead of using hci slip.

But still I couldn't explain why you have more power consumption when enter SystemOFF mode. Could you try to enter system off right in the bootloader (after you sending the byte) and see what happens ? Would you be able to reproduce the issue with nRF51 DK ?

[jpreston]

Just to add further information to this problem (we had it crop back up again), the current draw was a result of our host processor waiting to process data received from the nRF51. Since that was still in development, we never reset our internal flag. Hung, your advice regarding using app_uart directly is still valid, so I will now verify this answer.