Power Consmuption issue in nrf51 during advertising packets

RE: Power Consmuption issue in nrf51 during advertising packets

Hung Bui — Tue, 07 Jul 2015 11:02:29 GMT

@Brajesh: No, you either need to calculate it, or you can try to toggle a GPIO pin before and after you finish the task. Then use a logic analyzer or oscilloscope to measure the distance between.

RE: Power Consmuption issue in nrf51 during advertising packets

Brajesh — Tue, 07 Jul 2015 09:58:04 GMT

Okay @Hung Bui, will get back to you with stats in SDK examples, but can you please guide me how can i read CPU processing time ?

RE: Power Consmuption issue in nrf51 during advertising packets

Hung Bui — Tue, 07 Jul 2015 09:54:27 GMT

@Brajesh: What I meant was the CPU processing time, not the time your device remain in connection. Usually it's only dozens of micro second for CPU processing time depends on what you process. And is 0 microsecond if you don't have any interrupt handler or any processing in the main loop. Let me know when you have the stats on testing with our example.

RE: Power Consmuption issue in nrf51 during advertising packets

Brajesh — Tue, 07 Jul 2015 05:13:16 GMT

@Hung Bui,

It can vary how long we keep it in Connected mode, it can vary from 10 seconds to 2-3 hours or even more, but for now it is just for testing purpose and CPU is on all the time the device is connected, or if you are asking something else please let me know , I didn't get it exactly. I would try the SDK example and will come up with stats. Thanks :)

RE: Power Consmuption issue in nrf51 during advertising packets

Hung Bui — Fri, 03 Jul 2015 08:19:18 GMT

@Brajesh: Depends on which timer you are using, if you use the RTC timer (app_timer) then the current consumption should be few uA. If you use the timer running on 16MHz the current consumption will be 30uA+400uA (or +700uA depends on the 16MHz clock source) => Anyway it can't be the timer running on 16MHz clock.

When in connection how long in a conection event do you keep the CPU on (to do interrupt handler for example) ?

I would suggest you to test with our example. You can either try with ble_app_pwr_profiling (which is power optimized) or with any normal example , ble_app_hrs for example.

RE: Power Consmuption issue in nrf51 during advertising packets

Brajesh — Fri, 03 Jul 2015 05:34:36 GMT

@Hung Bui, Yes' I'v made sure that there is no other peripheral apart from timer except few GPIO's. As per datasheet, timer consumes 30uA while counting down which probably tells why it is taking 30uA in between BUT the same timer is running at the start for 15 seconds and device consumes only 5uA during that period.
But I'm more worried about the power consumption during connected period when it consumes 2-3 mA. I've also made sure i stop the timer when device gets connected. I'm using following GAP connection parameters for the connection setup.

MIN_CON_INTERVAL - 20ms MAX_CON_INTERVAL - 75ms CONN_SUP_TIMEOUT - 4sec SEC_PARAM_TIMEOUT - 30sec SLAVE_LATENCY - 0

These are the default connection parameters , can you please let me know what is the expected power consumption during connected period. Do i need to change any of these parameters to reduce consumption ?

Thanks

RE: Power Consmuption issue in nrf51 during advertising packets

Hung Bui — Thu, 02 Jul 2015 14:34:06 GMT

@If you have other peripheral runing such as crystal, timer you would need to add them to the total power consumption. How accuracy is your power supply current measurement ?

Regarding the 30uA current consumption, have you made sure there is no other peripheral running on the board, and on the chip, except for the timer ? What do you do when at the advertising time out ?

2-3mA when in connection is still pretty high, which connection interval did you use ?

RE: Power Consmuption issue in nrf51 during advertising packets

Brajesh — Thu, 02 Jul 2015 10:25:16 GMT

Hi, I have noticed on this thread " devzone.nordicsemi.com/.../ " that in Idle (sleep) mode " The base current consumption in this mode is given in table 32 in the nRF51822 PS v3.1 as I_ON, 2.6 µA. ". But in my case as i explained above minimum current drawn is 5uA and afterwards it never returns to 5uA, it keeps on toggling between 250uA and 30uA as per timer and advertisement. Please suggest why i don't get 2.6uA in sleep mode.

Thanks in advance.

RE: Power Consmuption issue in nrf51 during advertising packets

Brajesh — Thu, 02 Jul 2015 08:51:59 GMT

@Hung Bui. I am measuring consumption using a multi point Power supply. Now i come up with correct measurements as previous power supply had issues with resolution. Following are the observations based on power supply monitor. System starts and goes to Sleep(using sd_evt_wait API) mode immediately after all initialization. Timer starts (for 15 seconds) to wake up device in every 15 seconds. For first 15 seconds(when device is in sleep), the current consumption is 5uA. After 15 sec, timer handler starts advertisement (with TIMEOUT 5 seconds) and consumes ~250 uA (for 5 seconds) and then for next 10 seconds consumes 30uA. Afterwards, It keep on toggling between 250uA and 30uA . Not sure Why it doesn't show 5uA again ? After connection, device consumes 2-3mA. Does this sound alright now ?

RE: Power Consmuption issue in nrf51 during advertising packets

Hung Bui — Wed, 01 Jul 2015 15:58:47 GMT

@Brajesh: No it's still too high. As I mentioned it should be on average 0.03mA.

Have you tried with the default example in the SDK v5.2 ? The BLE HRS project , for examle ? How did you measure the current consumption ?

RE: Power Consmuption issue in nrf51 during advertising packets

Brajesh — Wed, 01 Jul 2015 13:02:39 GMT

Thanks Hung Bui for response. I am using Softdevice_6.0.0 and SDK-5.2.0.39364. I have made some modifications now to reduce power consumption. I'm running a timer which wakes up system from sleep mode in every 15 seconds and start advertising for 5 seconds(TIMEOUT). Now the cosmuption has reduced to 4mA and 5mA (while advertising for 5 seconds). And after connection it consmumes 9mA continuously. does it sound alright to you or still this is high than expected ?

RE: Power Consmuption issue in nrf51 during advertising packets

Hung Bui — Wed, 01 Jul 2015 11:50:46 GMT

@Brajesh: Constant consumption of 10mA, is way to0 high if you just doing advertising. It should be about 30uA when doing advertising with 1 second interval. Could you let me know about your set-up? Schematics, layout, how you measure the current consumption ? Which firmware did you use (SDK, softdevice version ) ?