nRF52-DK with HRM application - expected average current?

RE: nRF52-DK with HRM application - expected average current?

Kenneth — Thu, 17 Jan 2019 13:48:31 GMT

I found this link that may be useful for others that find this thread in future:

https://devzone.nordicsemi.com/b/blog/posts/optimizing-power-on-nrf52-designs

RE: nRF52-DK with HRM application - expected average current?

Scott — Thu, 17 Jan 2019 13:41:32 GMT

I appreciate the help, no matter how small. Thanks, Kenneth!

RE: nRF52-DK with HRM application - expected average current?

Kenneth — Thu, 17 Jan 2019 12:50:46 GMT

Not sure how much help I was in this case, but good an FAE stepped in an found that dcdc was not enabled by default. I have reported it internally (NRFFOETT-2213).

Best regards,
Kenneth

RE: nRF52-DK with HRM application - expected average current?

Scott — Wed, 16 Jan 2019 21:30:18 GMT

Kenneth and DevZone,

I got some help from my local FAE, and he confirmed that he saw similar current values to what my setup was reporting.

Further, he indicated that enabling the DC-DC converter could reduce the current consumption by ~40%. This was accomplished by adding the line:

sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE);

right after the call to advertising_start(erase_bonds); in main.c.

After rebuilding the project in Release mode, reprogramming my nRF52-DK, and reinstalling the PPK, the average current during advertising dropped to about 370 uA. Much better! Very grateful for the excellent help on this.

Some other techniques can evidently be used to reduce power further, including disabling the UART logging, and increasing the advertising interval and connection interval. I will continue to experiment, but this one call made a huge difference in average current draw.

Thanks for the help, Kenneth and Nordic!

RE: nRF52-DK with HRM application - expected average current?

Scott — Wed, 16 Jan 2019 15:12:16 GMT

Yes, after programming the Release configuration, I power cycled the nRF-DK board. LED1 starts blinking indicating that advertising has started.

I then started nRF Connect and launched the Power Profiler. I selected the serial port (COM8).

I then get a confirmation dialog that asks "Would you like to program the development kit on COM8 (682153254) with the required firmware?" I'm not sure why this is happening. Can you explain?

If I say Yes, I get notifications in the Log window "Failed to read PPK metadata" and "Failed to start the PPK". I exited nRF Connect and re-ran it, launching the Power Profiler again. Same Log messages. After restarting Power Profiler the third time, I get a Log message indicating "PPK started". When I click Start within the Power Profiler, I can see the advertising and my average current is around 582 uA.

Am I doing something wrong?

Thanks for your help!

RE: nRF52-DK with HRM application - expected average current?

Kenneth — Wed, 16 Jan 2019 14:58:37 GMT

First a question, have you power cycled the board to avoid it is still in debug mode after programming the firmware?

Best regards,
Kenneth

RE: nRF52-DK with HRM application - expected average current?

Scott — Wed, 16 Jan 2019 14:56:56 GMT

Kenneth, I did a quick search through sdk_config.h to see what logs are enabled. I found the following:

C:/Nordic_Semi/nRF5_SDK_15.2.0/examples/ble_peripheral/ble_app_hrs/pca10040/s132/config/sdk_config.h:#define NRF_LOG_ENABLED 1
C:/Nordic_Semi/nRF5_SDK_15.2.0/examples/ble_peripheral/ble_app_hrs/pca10040/s132/config/sdk_config.h:#define NRF_SDH_BLE_LOG_ENABLED 1
C:/Nordic_Semi/nRF5_SDK_15.2.0/examples/ble_peripheral/ble_app_hrs/pca10040/s132/config/sdk_config.h:#define NRF_SDH_LOG_ENABLED 1
C:/Nordic_Semi/nRF5_SDK_15.2.0/examples/ble_peripheral/ble_app_hrs/pca10040/s132/config/sdk_config.h:#define NRF_SDH_SOC_LOG_ENABLED 1
C:/Nordic_Semi/nRF5_SDK_15.2.0/examples/ble_peripheral/ble_app_hrs/pca10040/s132/config/sdk_config.h:#define PM_LOG_ENABLED 1

Could these have an impact on the average current? I am new to the nRF52 and SDK, so I am not even sure what these defines actually control. Do they generate output via the UART, or via the Segger JLink RTT?

Apologies for the "newbie" questions, but I am trying to get up the learning curve, which seems a bit steep at the moment!

Thanks again,

Scott

RE: nRF52-DK with HRM application - expected average current?

Scott — Wed, 16 Jan 2019 14:32:06 GMT

Thanks for the pointer, Kenneth. I do not understand what could be wrong with my configuration. I am trying to use the "stock" ble_app_hrs_pca10040_s132 heart rate monitor peripheral. I am using nRF5_SDK_15.2.0_9412b96. I have selected the Release configuration in Segger Embedded Studio, done a rebuild, and have then selected Build and Run

Perhaps there are peripherals turned on that I'm not aware of, or do not fully understand the purpose of. One example is in sdk_config. NRF_LOG_ENABLED is defined to 1. Could that be generating unexpected UART traffic that is driving the current up?

I have attached my sdk_config.h. Would it be possible for you to run this example with the PPK to see if you get similar current measurements to what I am seeing?

devzone.nordicsemi.com/.../0523.sdk_5F00_config.h

Thank you for your help.

Scott

RE: nRF52-DK with HRM application - expected average current?

Kenneth — Wed, 16 Jan 2019 11:55:37 GMT

If you disable debugging output and don't have other peripheral activity (uart, spi, twi), then the chip should draw the current shown here:
https://devzone.nordicsemi.com/power/