What is the power and clock model of peripheral in NRF51?

RE: What is the power and clock model of peripheral in NRF51?

Bee — Sun, 04 Jan 2015 00:39:23 GMT

Thanks a lot!

RE: What is the power and clock model of peripheral in NRF51?

Stefan Birnir Sverrisson — Fri, 02 Jan 2015 07:37:42 GMT

Hi I updated references to documentation and erased the comment about the PAN since it is no longer relevant for the new documentation. So the numbers in the current nRF51822 should be correct.

RE: What is the power and clock model of peripheral in NRF51?

Bee — Wed, 31 Dec 2014 02:14:47 GMT

Hi! I just saw "Please also note that there is a PAN item on the current consumption being higher than specified for the current chip revision." I need that PAN to resolve a problem about system off current consumption, but the link of PAN is Disabled. Could you please give me a new link of that PAN?

RE: What is the power and clock model of peripheral in NRF51?

Matt Leising — Mon, 09 Jun 2014 18:52:14 GMT

Are there any examples for nrf6310 that demonstrate power off and wake up via a sense detect configuration on a pin? I am having some trouble understanding that. Also, if I want to configure a pin for sense low to high, what would the threshold voltage be? Is it more recommended to have it set for sense low?

RE: What is the power and clock model of peripheral in NRF51?

Ole Morten — Mon, 28 Oct 2013 10:05:50 GMT

Since this is mostly unrelated questions, it would have been great if you could post them separately instead of hi-jacking this question. I'll try to answer them briefly here, but if you have follow-up-questions, please submit a new question.

1., 4. See this question: https://devzone.nordicsemi.com/index.php/why-does-my-nrf51822-consume-1-ma-in-sleep

There are several examples in the SDK, including ones that use low-power modes. If there is anything in particular you're missing, please see if there are any interesting questions here on the Developer Zone, or submit a new one, and we'll try to help you.
Since the radio API of BLE and ANT are very different, it's not easy to share code between them. However, all the hardware examples are equal, since they interface with the hardware directly instead of the softdevice API. All of those examples should be in the Board/nrf6310 folder. Even if you have the Evaluation Kit (pca10001), these examples should still be useful, but you may have to change the pinout to use them successfully.

RE: What is the power and clock model of peripheral in NRF51?

Ole Morten — Mon, 28 Oct 2013 10:01:24 GMT

Have you seen this question? https://devzone.nordicsemi.com/index.php/why-does-my-nrf51822-consume-1-ma-in-sleep

RE: What is the power and clock model of peripheral in NRF51?

roger hayes — Mon, 28 Oct 2013 02:21:50 GMT

Update: Per above, we measure about 1.7Ma while the WFI is active. HOWEVER: If the power is taken off the circuit and it's re-powered, it drops to about .020Ma current draw?

What's going on??

RE: What is the power and clock model of peripheral in NRF51?

roger hayes — Sun, 27 Oct 2013 23:21:54 GMT

Ole - Thanks for your comments - Please keep going:

[b]YOu said "System on, idle In this mode, all peripherals that are enabled when entering sleep stays enabled, and you can wake up on any interrupt. All clocks and regulators that are not required by a running peripheral will be turned off, but all RAM and registers are retained. When the chip comes out of sleep, it continues where it left off.

With the soft devices, you can enter this sleep mode using sd_app_event_wait(), and if you don't use the softdevice, you can use __WFI().

The base current consumption in this mode is given in table 23 in the PS as I_ON, 2.3 µA. The current consumption of any running peripheral, and their required clocks and regulators will come on top of this. The block requirements of the different peripherals can be seen in table 24 in section 8.3 in the nRF51822 PS. "[/b]

Further - I cannot seem to get below 1.69Ma current loading w/ the _WFI as per above. The wait is work ing well (per a gpio LED flask between loops) and i see the current drop from about 4.2Ma while active and the lower when it's sleeping. This is still WAY too much current loading for the life we're looking for. Assuming that the RTC requires a clock, what are our options on killing the peripherals. In my case, ADC is disabled, and the ANT is not enabled yet.
Where can one find competent, complete examples of the nrf_wait_for_app_event calls?? The documents leave LOTS to be desired and cause lots of struggles w/ the new-comers to NS. Other makers are flooded with examples and variations of them - NS does not seem to have it there..??
Note that I notice lots of examples referencing the BTE development sets (that are still Corex-0 based?) but are missing from the NRF (ANT sdk) examples? Are they interchangeable, excluding the radio basis'. Why are the examples not global to the SOC's?
I stumbled into getting the nrf_wait_for_app_event working a few days ago (my fault) but cannot seem to get it working again. I had it to ~.00-3Ma at one point but lost it and did not consider that it would be this difficult to get it running again. I've never gotten it to work since.

tks!

RE: What is the power and clock model of peripheral in NRF51?

Ole Morten — Tue, 10 Sep 2013 12:29:05 GMT

When you enter system off, everything is turned off automatically, and no preparation is needed.
Only the 16 MHz clock is forced on in CONSTLAT, not anything else.
Both in WFI and when running normally, only peripherals that have been enabled are powered.
See above. The only thing you should care about is to enable peripherals when you need them, and disable them as soon as possible afterwards, no matter if you are currently running or sleeping.

I've also tried to clarify the above answer somewhat, so I'd be happy if you could accept it if you found it useful, by clicking the "Accept as answer" button below it. That makes it easier for others to find. :-)

RE: What is the power and clock model of peripheral in NRF51?

paulinx — Tue, 10 Sep 2013 11:27:25 GMT

Can anyone answer my new questions?

RE: What is the power and clock model of peripheral in NRF51?

paulinx — Mon, 09 Sep 2013 12:54:37 GMT

OK, I got something from your answer. Please correct me if i made mistake in followings.

In off mode, everything can be turned off are turn off from clock, turn off from power, no retention.
In constant latency mode, every power and any clock are forced on, even in wfi.
In low power mode, when in wfi, peripheral, which is not enabled, is not clocked and power off with retention. When not in wfi, every module is powered and clocked.
So if I explicitly power off some module that i need not throughout my application by POWER register, i will save power in RUN mode.

Am I right?

RE: What is the power and clock model of peripheral in NRF51?

Ole Morten — Mon, 09 Sep 2013 05:52:09 GMT

For information on the low frequency clock model (32kHz), look at this thread.

For information on the high frequency clock model (16MHz), look at this thread.

With the nRF51822, there is just two power modes you need to be aware off, system on idle and system off.

System on, idle In this mode, all peripherals that are enabled when entering sleep stays enabled, and you can wake up on any interrupt. All clocks and regulators that are not required by a running peripheral will be turned off, but all RAM and registers are retained. When the chip comes out of sleep, it continues where it left off.

With the softdevices, you can enter this sleep mode using sd_app_event_wait(), and if you don't use the softdevice, you can use __WFE(). sd_app_event_wait() function (inside power_manage() function) is used in most of the examples in the nRF51 SDK. An example on how to use __WFE() is given in the system-on-wakeup-on-gpio example on Nordic's Github.

The base current consumption in this mode is given in table 32 in the nRF51822 PS v3.1 as I_ON, 2.6 µA. The current consumption of any running peripheral, and their required clocks and regulators will come on top of this. The block requirements of the different peripherals can be seen in table 33 in section 8.3 in the nRF51822 PS v3.1.

Sub-power modes There are also two sub-power modes, the default LOWPWR, and CONSTLAT. These are described in section 11.1.4 in the nRF51 Reference Manual. Using the CONSTLAT mode will keep the 16 MHz clock running all the time, so that the wake-up time is constant and low (< 3 µs). This comes with the cost of having the 16 MHz clock always running, even when no peripherals need it, which gives a consumption increase of several hundred µA. The default is to use LOWPWR.

System off In this mode, all peripherals, clocks and regulators are turned off, and the only wake-up sources are a reset and GPIOs with SENSE configured (SENSE field in PIN_CNF set to low or high). By default, all RAM is also turned off, but this can optionally be kept on by changing the RAMON register. When the chip comes out of this sleep mode, it always starts from reset, and RAM (if not configured otherwise) and registers that are not marked as retained are cleared. See table in section 11.1.7.8 in the nRF51 Reference Manual for details on reset behavior.

With the softdevices, you can enter this mode with sd_power_system_off(), and without them, by writing 1 to the SYSTEMOFF register in the POWER peripheral. When entering system off, all peripherals are automatically turned off, so no preparation is needed.

The base current consumption in System Off is given in table 32 in the nRF51822 PS as I_OFF, 0.6 µA. RAM retention increases this, as stated in the same table. Since all peripherals and clocks are turned off, which peripherals are enabled when entering this mode doesn't matter for the current consumption.

General considerations All peripherals are per default off, and only peripherals that have been explicitly enabled will be on at any time. To achieve low current consumption with the nRF51, the general recommendation is therefore to only turn perpiherals on for as short time as possible, and explicitly turn them off whenever they are not needed. This is usually done by writing a Disabled value to the peripheral's ENABLE register, and will ensure that they don't keep the clock running when it isn't actually needed.

In addition, it's always safe to enter system on, idle, from the main context, since whatever has been enabled before you enter this mode will stay enabled through it. This is therefore very well suited to be the only action in the main loop, and you should make all other actions in your application depend on interrupts or events coming either from perpiherals (timers) or from the BLE/ANT stacks.

Use system off only when you can live with requiring user action (i.e. button presses) to wake you up again, and with a reset being done (i.e. when you don't have any state information that you need to preserve).

Finally, when doing current measurements, remember that the debug interface of the nRF51 consumes > 1 mA, so do a power-on-reset after flashing. See this question for details.

Edit: Some clarifications.