Hi there,
I'm looking forward to improve our firmware in terms of power consumption. Therefore we would like to use Power Debugging mechanism which is support by IAR Workbench. The charm is we can correlate power samples directly with the pc counter which helps a lot improving overall power consumption.
When I start this analysis now with our firmware running on the nrf52840 DK, supplied via USB @nrf USB port and attaching the I-scope together with an I-jet Debugger. Trace switch is set to Alt. and Power Source to VDD, SB40 is cut as mentioned in the getting started. Since the Dk does not support power supply through the debugger TgtPwr pins not connected I chose aboves setup for my measurements.
The measured current is approx. twice as high compared to non-Debugging operation. Which makes me feel that something with the DCDC Reg0 is not working correct.
For instance on startup my radio is in permanent listen mode for Beacons which results in 6.8mA; matches well with the datasheet taking in consideration all enabled peripherals - during the debug session I measure 13.8mA.
Another idea was that i get some interference with the DAP interface during the debug session, which is not the case for other controller e.g. an STM32F429II where I'm able to debug sleep modes with some uA without any issues. This can be reproduced with any example from the SDK 15.2 library which uses idle mode modes in SYSTEM_ON mode (sd_app_evt_wait or WFE)
Ideas are welcome.
Best Chris
