The best way to save energy in an application

RE: The best way to save energy in an application

Jared — Wed, 06 Jul 2022 12:42:44 GMT

Hi,

I think you need to analyze your application a bit more in dept. At least you should measure the average current consumption of the application and know what state it's in. You write a lot of power but could you specify exactly how much? Using the online power profiler tool and the PPK 2 would be a great start.

This is also a good read.

regards

Jared

RE: The best way to save energy in an application

John12 — Sat, 02 Jul 2022 08:50:31 GMT

Hi, I'm using my partner's custom board using nRF52833 as MCU. GPS, ModuleSim belong another brand. I'm not sure about peripherals, gps, modulesim I disabled, if it actually slept. So I tried to turn off all periperal and my custom board only advertise BLE signal. But It still consume a lot of power consumption.

RE: The best way to save energy in an application

Jared — Fri, 01 Jul 2022 09:25:38 GMT

Hi,

Is this the same custom board? In your original post you mentioned a nRF52833 based board, asset tracking, gps makes me think that it's a nRF9160 board? Have you done any measurement of the current consumption while it's in sleep?

regards

Jared

RE: The best way to save energy in an application

John12 — Thu, 30 Jun 2022 01:59:40 GMT

Hi, Jared. My custom board still consume a lot of power. With asset tracking device use gps, bluetooth, module sim I only use only 2 days with 700mAH battery. So can you suggest for me another methods like optimizing hardware, firmware or sth. About gps and module sim, It quite simple when I sleep it so I'm sure It consumes little power

RE: The best way to save energy in an application

Jared — Thu, 23 Jun 2022 13:03:54 GMT

Hi,

What is the problem, are you getting any specific errors? Could you specify them?

regards

Jared

RE: The best way to save energy in an application

John12 — Wed, 22 Jun 2022 06:51:10 GMT

Hi Jared,
Thanks for your reply. I'll try supply 1.8 and test my application. I have an problem with SAADC and PWM. It quite complicated to use low_power_pwm and low_power_saadc. Because almost time in my application I'm not using them. PWM used for ring the buzzer and SAADC read the battery level per 5 minutes. So I have an idea that use uninit of saadc and pwm by using app_pwm_disable(), nrfx_saadc_uninit() when I use them as shor time when an event trigger and close them almost the time.
I think It will consume same as low_power_pwm, low_power_saadc

RE: The best way to save energy in an application

Jared — Tue, 21 Jun 2022 13:56:53 GMT

Using 1V8 should be ok, but note that it sets the VDD_GPIO voltage to 1V8. If you are going to communicate with devices that uses a different voltage range such as 3V3 then you will need a level shifter.
Disabling logging is done by setting NRF_LOG_ENABLED to 0

RE: The best way to save energy in an application

John12 — Mon, 20 Jun 2022 02:56:43 GMT

hi Jared,
1. Like previous your reply. You confirm that I can supply 1.8v for nRF52833 to work saver energy than 3.3V.
Does it affects performance or any other exception like peripheral, BLE strength, libuartes speed, other handler...?
Or it is similar 3.3v but saver than ? I mean I only supply from external source for nRF 1.8v for all process.
In my module it doesn't have conductor connect with DCC so I think I can't use DC/DC converter.

2. I followed this thread to disable logging => I only set NRF_LOG_DEFAULT_LEVEL 0 for disable logging ? May I miss some configs to disable logging? I'm just using NRF_LOG_INFO to debug, may it is simillar RTT backend log ?

RE: The best way to save energy in an application

Jared — Thu, 16 Jun 2022 12:23:00 GMT

Hi,

That thread is a bit outdated, I would rather that you go through the product specification which explains it in detail.

The nRF52833 has two regulator stages. The first one REG0 is only used in High Voltage mode. Each stage has a dedicated LDO and DC/DC regulator. The DC/DC regulator requires external components but is more power efficient than the LDO.
Yes
See my answer to option 1.
When DC/DC is enabled the CPU will automatically switch between the LDO and DC/DC depending on the power requirement.

regards

Jared

RE: The best way to save energy in an application

John12 — Thu, 16 Jun 2022 07:49:29 GMT

Hi Jared,
About regulator I have some confusions about this topic
I follow this thread but It hard to understand

1. What is the difference between external DC/DC converter and internal DC/DC converter ?
2. May I supply 1.8v voltage for my nRF saving energy working?
3. My custom board don't have LC so It seems can not enable DC/DC converter ? What is the alternative solutions?
4. DC/DC is automatically enabled when voltage goes below 2.1V => LDO is disabled and vice versa when voltage goes up?

RE: The best way to save energy in an application

Jared — Wed, 15 Jun 2022 07:12:42 GMT

Hi,

[quote user="John12"] how and when I should enable DC/DC converter ? Any blog post ?[/quote]

If you're using the Softdevice then you can use the SD API by calling sd_power_dcdc_mode_set() in the beginning of main().

[quote user="John12"]. what is the advantage when I make app_timer use external external crystal ? how can use external crystal? I attached my sdk_config.h please check for me.
May It here ? What is RC, XTAL, SYNTH ?[/quote]

The external low frequency crystal has a lower run current then the RC oscillator. Thus it will consume less current. See the clock section in the product specification for a description of the different LFCLK sources.

regards

Jared

RE: The best way to save energy in an application

John12 — Tue, 14 Jun 2022 17:11:12 GMT

Hi Jared,
I can't find any schematic from this module
But I confirm that is external crystal.
So please suggest for me:
1. how and when I should enable DC/DC converter ? Any blog post ?
2. what is the advantage when I make app_timer use external external crystal ? how can use external crystal? I attached my sdk_config.h please check for me.
May It here ? What is RC, XTAL, SYNTH ?
Thank for your reply.
I'm new at this topic so your reply help me a lot.

// <o> NRF_SDH_CLOCK_LF_SRC  - SoftDevice clock source.

// <0=> NRF_CLOCK_LF_SRC_RC
// <1=> NRF_CLOCK_LF_SRC_XTAL
// <2=> NRF_CLOCK_LF_SRC_SYNTH

#ifndef NRF_SDH_CLOCK_LF_SRC
#define NRF_SDH_CLOCK_LF_SRC 1
#endif

RE: The best way to save energy in an application

Jared — Tue, 14 Jun 2022 12:18:18 GMT

Hi,

There are two internal regulators on the nRF52833 that regulates the supply down to the system voltage in two stages. The internal regulators can either use an internal LDO or a DCDC for each step. Using the DCDC requires external inductors, but the benefit of using DCDC is that it's more power efficient.

It seems like it has an external LFXO crystal, do you have the schematics?

The app timer would automatically use the external low frequency crystal, if it's chosen as the LFCLK clock source in the sdk_config.h file of your project.

regards

Jared

RE: The best way to save energy in an application

John12 — Tue, 14 Jun 2022 08:02:36 GMT

Yes, I have external components for DCDC. But I think it only used for convert 4.2v into 3.3v to compatible with module. What is other functions of DCDC converter ??
I got an sentence "enabling and populating the DC/DC converter" when I read blog post you suggested. But I have some confusions about this. Seem DC/DC converter like a peripheral. How can I "enabling and populating the DC/DC converter" ? By coding ?

I researched that there is an regulator that is LDO. What is the difference between them ?

Here is the module I used. It contained external LF crystal ? I'm using app_timer. How can I use external LF crystal like you suggest ?

RE: The best way to save energy in an application

Jared — Tue, 14 Jun 2022 07:39:42 GMT

Hi,

Does your custom board have external components for the DCDC regulator? Do you have an external low frequency crystal?

regards

Jared

RE: The best way to save energy in an application

John12 — Mon, 13 Jun 2022 16:22:28 GMT

Hi Jared, thanks for useful confirm
Please explain for me more detail. I new at decrease TX power, DCDC and external LF crystal. Please give me an example. I'm using an custom board developed by my partner, I only dev firmware so I'm not specialized at hardware.

RE: The best way to save energy in an application

Jared — Mon, 13 Jun 2022 10:49:20 GMT

Hi,

These are all very good measures for low power. For the SAADC you can follow our low-power SAADC example which uses the RTC to schedule samples, see this. The logger should definitely be disabled if you want to have low current consumption. For the BLE you can decrease the TX power, use DCDC and external LF crystal.

Here is a blog post about optimizing power on nRF52.

regards

Jared