RE: Low power BLE advertising with Zephyr on nrf52840, is it supported?

jeremyherbert — Thu, 14 May 2020 07:37:03 GMT

Hi Håkon,

Thanks for your quick reply. I just tried `nrfjprog --reset` and it now works fine; I'm measuring about 6mA during TX and otherwise a few uA during sleep.

I was using openocd to flash; it seems that when using openocd to flash the device, it is not reset correctly and perhaps the debugger stays enabled? I'm using the version that goes with Zephyr: https://github.com/zephyrproject-rtos/openocd and I'm using it over nrfjprog because the IDE I am using (CLion) supports debugging/flashing with openocd.

The invocation is this:

/home/jeremy/zephyr-sdk/sysroots/x86_64-pokysdk-linux/usr/bin/openocd -c "tcl_port disabled" -s /home/jeremy/zephyr-sdk/sysroots/x86_64-pokysdk-linux/usr/share/openocd/scripts -c "gdb_port 3333" -c "telnet_port 4444" -f /home/jeremy/Desktop/low_power_test/nordic_nrf52_dk.cfg -c "program \"/home/jeremy/Desktop/low_power_test/cmake-build-debug/zephyr/zephyr.elf\"" -c reset -c shutdown

Open On-Chip Debugger 0.10.0+dev-01340-ga0e8edc4e-dirty (2020-02-14-05:38)
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html
Info : Zephyr: looking for target: cortex_m
Info : Zephyr: target known, params at 0x907220
Info : J-Link OB-SAM3U128-V2-NordicSemi compiled Jan 21 2020 17:30:48
Info : Hardware version: 1.00
Info : VTarget = 3.300 V
Info : clock speed 1000 kHz
Info : SWD DPIDR 0x2ba01477
Info : nrf52.cpu: hardware has 6 breakpoints, 4 watchpoints
Info : Listening on port 3333 for gdb connections
target halted due to debug-request, current mode: Thread 
xPSR: 0x01000000 pc: 0x0000140c msp: 0x20002408
** Programming Started **
Info : nRF52840-xxAA(build code: C0) 1024kB Flash, 256kB RAM
Warn : Flash protection of this nRF device is not supported
Info : Padding image section 0 at 0x0000cef0 with 5 bytes
Info : Padding image section 1 at 0x0000d3fd with 3 bytes (bank write end alignment)
Warn : Adding extra erase range, 0x0000d400 .. 0x0000dfff
** Programming Finished **
shutdown command invoked

RE: Low power BLE advertising with Zephyr on nrf52840, is it supported?

Håkon Alseth — Thu, 14 May 2020 06:58:12 GMT

Hi,

Thank you for providing sample code and configuration, compiled out-of-the-box.

I cannot see that you are missing any settings. 1.3 mA is high. Are you connecting with the debugger? That normally gives a bit higher current consumption on nRF52840 (around 1.6 mA). If I do not power cycle or reset the device after programming (ninja flash), I see approx. 1.37 mA. Could this be the issue?

I took the samples/bluetooth/peripheral_dis, pasted your code into main.c, and added these to prj.conf:

CONFIG_SYS_POWER_MANAGEMENT=y
CONFIG_SYS_POWER_DEEP_SLEEP_STATES=y
CONFIG_SYS_PM_STATE_LOCK=y
CONFIG_SERIAL=n

After power cycling (or issuing a "nrfjprog --reset"), this behaves as expected when testing with nRF52840-DK (SB40 cut), with the lowest power consumption is approx. 4 uA, and throttles higher once per second, per the advertising interval you set.

Kind regards,

Håkon