Low Power Consumption nRF8001

RE: Low Power Consumption nRF8001

run_ar — Mon, 27 May 2019 09:07:41 GMT

Are you sure you are keeping the input pins of the nRF8001 at a defined state all the time? If the application mcu leaves one of those floating it would typically draw around 100µA.

RE: Low Power Consumption nRF8001

jamilaaria — Mon, 27 May 2019 00:21:04 GMT

I see, thanks for the suggestion. I will try that when I measure again.

As for the table, it shows the average current (mA) consumption when I set slave latency = 10 and connection interval min=15ms max=15ms and I measure 0.194mA. I increased the slave latency to 10 and 20 and you can see the average current consumption accordingly.

As mentioned in my previous replies, I seem to be getting higher average current consumption (offset of about ~100uA) compared to the current consumption calculator.

RE: Low Power Consumption nRF8001

run_ar — Thu, 23 May 2019 13:24:26 GMT

It's not possible to measure the current properly using a multimeter while the radio is active as the multimeter is to slow. For current measurements during sleep it is ok. For accurate current measurements you need a dcdc power analyser, or similar. Our PPK is also an option.

I am not sure what your table is showing. The current consumption calculator will give an estimate based on your use case.

RE: Low Power Consumption nRF8001

jamilaaria — Wed, 22 May 2019 10:47:52 GMT

For the previous graph, I was using a multimeter that gets the average current.

Also, I tried varying and increasing the slave latency, but it seemed that the current consumption was much higher. I was expecting it to be lower. Is this what's expected?

Connection Interval (15ms/15ms)
	Slave Latency
Cycle Time	0	10	20
10 s	0.19414685	0.190959527	0.22098695
30 s	0.056611663	0.064026546	0.06247249

RE: Low Power Consumption nRF8001

run_ar — Tue, 21 May 2019 12:11:04 GMT

How are you measuring this? looks like the sampling rate might be to low to properly measure the current consumption. Spikes during radio activity is normal as that would require a lot of power.

RE: Low Power Consumption nRF8001

jamilaaria — Thu, 16 May 2019 23:18:59 GMT

Thanks for the recommendation, however, I will not be able to use a newer device yet.

I used the nRFgo studio for the average current consumption, and theoretically I should be getting ~133uA in average.

However, when I tested it, I got about ~230uA in average. Yes, I have observed that nRF8001 draws less than 500nA while in deep sleep. My concern is that there is a high peak during advertising which peaks ~6mA. And also, there are instances where I do not see the peak, but I do not understand why.

Would you have any recommendation to further lower down the current consumption? Thanks!

RE: Low Power Consumption nRF8001

run_ar — Wed, 15 May 2019 12:56:05 GMT

The nRF8001 should draw less than 500nA while in deep sleep. Please check the state of the input pins in this case, i.e. make sure they are not asserted by the application mcu.

You can calculate the theoretical power consumption using the power consumption calculator in nRFgo studio.

Please also note that the nRF8001 is an old device, so it is recommended that you use a newer device such as the nRF52 series.

RE: Low Power Consumption nRF8001

jamilaaria — Wed, 15 May 2019 12:06:14 GMT

The whole board (including the uC,nrf, and accel) consumes an average of 400-500uW for 30 cycle time, but I need to lower down this to around 200uW. I have this cycle: wakeup - connecting - sending data - disconnect - sleep and I measure a peak of 6mA (drawn by the nrf8001).

One other option that I am thinking is to keep the connection during the 30 cycle time rather than connect - sending - disconnect. Because I think that advertising must be consuming more power. Will you have any suggestion for this?

RE: Low Power Consumption nRF8001

run_ar — Wed, 15 May 2019 11:22:17 GMT

Since I have no idea what your current power consumption is, the only suggestion I have is to make sure you go the deep sleep whenever you are disconnected and not advertising. Remember that all input pins need to be in a defined state to avoid power leakages, ref GPIO overview.