# Low Power: How much current? [Solved]

• As ulpnode is not released yet. I tried to reproduce how it works and get it! If you want to understand Please, I can't advise you enough to read this post on ulpnode engine management http://hallard.me/ulpnode-low-power-secret/ so you will understand. It is based on a dc booster and a voltage supervisor. This is what I am doing.
And for my tests : 2xaaa battery so 3V. for mosfets, I tried with si2399, CJ2305 very cheap on ali. And BS250 on breadboard worked too.

• Lets put this all in perspective. a CR2025 coin cell is 165mAh.

If we are sleeping forever @ 6uA that means the circuit will last for: 27,500 hours or 1,145 days. The question I guess we need to figure out is what is "good enough" for coin cell applications?

My goal is to figure out a way to sink the total circuit to around 1uA. That should be possible if Arduino is 100nA and NRF is 800-900nA.

So why does the NRF draw so much current when connected to Arduino? I know its been touched on already but is there a cleaner way in software without adding mosfets or extra hardware to have the NRF in sleep mode but not drawing any current from Arduino?

• @brolly759 said:

Lets put this all in perspective. a CR2025 coin cell is 165mAh.

If we are sleeping forever @ 6uA that means the circuit will last for: 27,500 hours or 1,145 days. The question I guess we need to figure out is what is "good enough" for coin cell applications?

My goal is to figure out a way to sink the total circuit to around 1uA. That should be possible if Arduino is 100nA and NRF is 800-900nA.

So why does the NRF draw so much current when connected to Arduino? I know its been touched on already but is there a cleaner way in software without adding mosfets or extra hardware to have the NRF in sleep mode but not drawing any current from Arduino?

Even if you wanted to turn the NRF completely off using just software, I don't see that it's even possible. It may require a hardware switch to pull its plug.

Here's some brainstorming:

According to the datasheet, NRF Powr Down state is defined as "All register values available are maintained and the SPI is kept active, enabling change of configuration and the uploading/downloading of data registers."

You need something to keep the NRF's memory alive in the registers, unless you prefer to pay the price of a full startup cycle (which is an option).

In theory you could lower the NRF's supply voltage to 1.9V, because that is the minimum specified in the NRF datasheet. Current might be similar, but I'm guessing that with lower voltage it would be using less energy in total?

If so, then notionally maybe you could dial down the NRF's voltage by putting a cap across across ground and its Vcc, and then sending it just enough PWM to make the capacitor voltage hover at 1.9V? Perhaps there's a more elegant way to do it, but lowering its voltage seems like the only avenue not yet explored that might yet payoff, short of just turning it off. Unfortunately, capacitors tend to be lossy, so it might be a net loss.

Or, if using Scalz's boost converters, maybe you could lower all voltages to the minimum 1.9V by simply not boosting them higher than that? You'd need an adjustable boost converter for that, assuming you run at a nominal 3.3V when the arduino isn't sleeping. Adjustable boost converters do exist, so I see no problem with that approach. The Atmeg328p can function even down to 1.8V, although you may need to operate it at 4Mhz if doing so (says the arduino spec sheet). If awake, would the arduino datalines still need to operate at 3.3V, or could they work just fine at 1.8-1.9v also? Important question: does awful boost conversion efficiency at such low voltages more than ruin the potential NRF energy savings from this approach, as outlined above?

If you could turn off the NRF's SPI, and later turn it on again, without losing the registry values, that might be worth exploring also. I don't know if that's feasible though. However, the arduino's SPI is turned off, so there's nothing for the NRF's SPI to talk to anyway during the Arduino's power-down sleep, so if you could turn off the NRF's SPI too (again, it may be impossible), it would make sense to do so. Correct?

Out of the above spitballing, the prospect of adjusting voltage to 1.91v through the boost converter to me sounds the most promising. A lot would hinge on the efficiency curves of the boost converter though. If the numbers don't support that, then maybe running the NRF's supply voltage separately at 1.91v would work?

Maybe there's a pony in there somewhere.

• dc booster sequence is not my idea! It is first Charles. But these type of sequence are well explained in app notes of supervisors and dc boosters.

In my case, I turn off nrf by mosfet . so all registers are lost I think. So I power and reinit it on wake up. and no problem of transmission, I didn't see any fails.

for dc booster, maybe you don't understand the concept of Charles ulpnode. This is a fixed 3v dc booster with true enable. you charge a capacitor on vcc. Turn off dc booster and go to sleep. Let the capa discharge. When capa vcc is < 2V. a supervisor chip irq toggle the enable pin of dc bosster and d3 int on arduino. You have a hardware watchdog which consumes very small current. On wake up maintain enable on booster. . of course, with the capa discharge 3v to 1.8v, you will have less power consumption. but the useful thing is the hw watdchdog generated by capa. choose right capa and adapt your cycles..

• @brolly759 Is your design finished or still evolving? Are you planning to say how you did it in exacting detail, or just in general terms? At the moment I see your results (above), but at the moment I'm not sure exactly what you did, other than it involved starting with a Pro Mini, removing the Power LED, removing the power regulator, and invoking a sleep cycle. Is the following the best summation to date? http://forum.arduino.cc/index.php?topic=341958.0 If so, please let me know, and I'll give it a more careful read. On the other hand, if something else is a better summation, please let me know what that is, and I'll add it instead to the round-up.

Yesterday I placed an order with Great Wall Electronics for 10 Arduino Pro Mini's. That may take anywhere from two to four weeks to arrive. Meanwhile, I should receive the three red Pro Mini's from Amazon (above) tomorrow. With those I plan to start with the same three steps as before and then see how the measurement numbers look. If promising, I guess I'll next proceed based on what I find in the links you and scalz provided:
http://forum.arduino.cc/index.php?topic=341958.0
http://www.gammon.com.au/power
hallard.me
jeenode
lowpowerlab

and see where that gets me. At the moment, those are the only guides I have that are reasonably detailed. If in addition anything else should be on that list, please let me know.

• @NeverDie I will rewrite everything up again. The numbers I posted about was me just unplugging wires and seeing what my current draw was.... haha the link is where my dual post is located where I am talking to Gammon about this problem

@everyone So Gammon said this about our problem:

"I am guessing you are parasitically powering the NRF. Before sleeping make sure you set the connections to it to high-impedance. For example, SPI.end() followed by making sure the SPI (and other two) pins are inputs (or maybe outputs and LOW). For example, a snippet from my code with that gadget:"

`````` bool ok = radio.write (&reading, sizeof reading);
SPI.end ();
// set pins to OUTPUT and LOW
for (byte i = 9; i <= 13; i++)
{
pinMode (i, OUTPUT);
digitalWrite (i, LOW);
}  // end of for loop
power_all_disable();
``````

I am looking in the library to see if we do SPI.end() before sleep but cant find anything...

• So an update, you can find all the sleep functions in the MySensor.cpp file.

• yes. Gammon is right. I needed to do pinmode output=0 when I tested. I didn't do the spi.end but I think is good thing to do.
@Neverdie: I hope and am sure you will get it!
in the mean time I am redesigning my board with some feedbacks you gave me. thx.
it will be 0805/atmel solderable version, no mini pro. and will be 5cmx2.3. same specs as I did on my other board. so far so good but now 4layer. only for rfm for the moment. can't do magie. but two boards on a 5cmx5cm. not expensive at elecrow... I hope I will get it finished for this week...

• YESSSSSSSSSSSSSSS!!!!! I got sleep down to 1.5ua - 1.6uA with NO hardware changes!!!!! WOOOT sorry, kinda excited here lol

• great I'm happy for you.

• Okay, so originally I was getting 2.7-2.9uA with Arduino/NRF. Stock MySensors library and Arduino 1.0.6 IDE. ( I am using the BinarySwitchSleep Sketch from MySensors lib)

To get even lower power.... If you open up mysensors.cpp the sleep function is there. For the BinarySwitchSleep sketch you are looking for this sleep function as there are a few:

``````SPI.end();
for (byte i = 9; i <= 13; i++)
{
pinMode (i, OUTPUT);
digitalWrite (i, LOW);
}  // end of for loop
``````

to this:

``````bool MySensor::sleep(uint8_t interrupt, uint8_t mode, unsigned long ms) {
// Let serial prints finish (debug, log etc)
bool pinTriggeredWakeup = true;
Serial.flush();
RF24::powerDown();
attachInterrupt(interrupt, wakeUp, mode);
if (ms>0) {
pinIntTrigger = 0;
sleep(ms);
if (0 == pinIntTrigger) {
pinTriggeredWakeup = false;
}
} else {
Serial.flush();
}
detachInterrupt(interrupt);
return pinTriggeredWakeup;
}
``````

and it will look like this:

``````bool MySensor::sleep(uint8_t interrupt, uint8_t mode, unsigned long ms) {
// Let serial prints finish (debug, log etc)
bool pinTriggeredWakeup = true;
Serial.flush();
RF24::powerDown();
attachInterrupt(interrupt, wakeUp, mode);

SPI.end();

for (byte i = 9; i <= 13; i++)
{
pinMode (i, OUTPUT);
digitalWrite (i, LOW);
}  // end of for loop

if (ms>0) {
pinIntTrigger = 0;
sleep(ms);
if (0 == pinIntTrigger) {
pinTriggeredWakeup = false;
}
} else {
Serial.flush();
}
detachInterrupt(interrupt);
return pinTriggeredWakeup;
}
``````

Because you are shutting off and turning all pins low, you will need to add this to the beginning of your program loop to reinitialize the NRF:

``````void loop()
{
sensor_node.begin();
``````

If you add both SPI.end(); and LOW pin loop, your current will be 1.5uA

• Some more facts here:

If you ONLY do the for/loop to shut off PIN9-13 in the sleep function and do NOT shut off SPI... you do NOT need to reinitialize the radio on wake-up.

The current draw for For/Loop LOW w/o shutting off SPI is 2.1uA-2.2uA.

This is a good and bad. If you have a sensor that is going to be switched on and off a lot, the re initialization time is noticeable on a fluke meter. You can see it staying high much longer. So, if someone knows how long it takes to initialize, then we can determine if shutting off SPI is worth it. ~600nA savings vs high reconnect time.

• @brolly759 said:

So, if someone knows how long it takes to initialize, then we can determine if shutting off SPI is worth it. ~600nA savings vs high reconnect time.

I have an o-scope, so once I get everything set up, I can try measuring that time duration for you if you like.

Really the comparison should be an energy comparison, which might be roughly::

((~600nA)(# microseconds powered-down)) vs ((arduino's current draw while powered up)(# microseconds extra setup time if NRF was turned off))

• I have an O-scope just dont know how to use it completely lol. Leaving work now. Stayed extra 2 hours to play with power settings lol

@NeverDie did you still need me to write up what I did or you followed it pretty much?

• @brolly759 said:

I have an O-scope just dont know how to use it completely lol. Leaving work now. Stayed extra 2 hours to play with power settings lol

@NeverDie did you still need me to write up what I did or you followed it pretty much?

I'd prefer to have a nice consolidated write-up for two reasons:

1. So I can be sure I'm following it right. If I do it differently, then any measurements I might get won't do you much good, if any. And,
2. So others, including noobs, can follow along to both understand it as well as replicate it for themselves, because then you leverage the true power of open source. It's well proven: the mores eyes on something, the better it gets, and the more everyone benefits from the experience. For that to work, the clearer the "something" is, the better. The more details the better too.

OK, finished editing.

• I keep watching you edit your post, its freakin me out! lol

• @Neverdie @brolly759 : I will follow your progress with interest and help if I can. For the moment, I have a lot of work before playing with my uCurrent. And for respect for Charles work, I am waiting his release. But when I will receive my boards (at then end of the month), if lib is not released yet, I will clean my code. And don't forget, I am using boosters and mosfets, so it is different. but roads are crossing of course. with booster what I like is, I will have 3.3v vcc during the whole battery life too.
Too late for me! 2am, lol. time to powerdown. See you soon

• Running Arduino+NRF24l01 w/ interrupt consuming 1.5uA in sleep

I am using this Arduino Nano Pro 8mhz 3.3v :link text
I am using this NRF chip: link text

Here is my test environment:

• Arduino Nano with desoldered jumper for bypassing voltage regulation (If you dont have bypass jumper on the knock off Nano, look at this post: link text )
• NRF connected via pinout on MySensors guide
• 3V direct supply from 2 AA Batteries
• uCurrent Gold testing voltage current
• Fluke 179 reading in mV
• Using the BinarySwitchSensor sketch in the MySensors library

If I upload the sketch as is with the recommended setup guide, Pin 2 or 3 is an interrupt pin and that goes to GND and acts as a switch. Pin 2/3 is HIGH and uses the internal pull up resistor. We will refer to the 2 different states of the switch as follows:

"oState" (Open, when Pin 2/3 does NOT touch GND)
"cState" (Closed, when Pin 2/3 touches GND)

When running everything I get these sleep numbers:
oState: 23-24uA
cState: 117uA

I downgraded my Arduino IDE from 1.6.5 to 1.0.6 and here are my new numbers:
oState: 2.5-2.7uA
cState: 98-100uA

Everything is looking good but my cState is still too high for any battery applications that I am trying to get.

Removed digitalWrite on pin 2/3. Connected 10M resistor from pin 2 to VCC. GND is switch to pin 2.
oState: 2.5-2.7uA
cState: 3.1-3.2uA

Reference measurements:

At this point I ran the "DallasTemperatureSensor" to test current using the WDT, I did NOT connect Temp sensor
Sleep current with WDT enabled @ 30 seconds: 7.6-7.8uA

Using "BinarySwitchSensor", remove NRF completely and only have Arduino:
Sleep current: 110-120nA OR .4-.5uA (had issues reading this but I believe it is the nA)

Connecting VCC/GND only to NRF to read standalone current:
NRF only: 800-900nA Shutdown current

Useless numbers while running the BinarySwitchSleepSensor sketch:
Sleep current: 2.7-2.9uA with NRF/Arduino fully connected
Sleep current with nRF GND disconnected: 1.7uA
Sleep current with nRF VCC and GND disconnected: 294nA
Sleep current with nRF VCC/GND/Pin9 disconnected: 281nA
Sleep current with nRF VCC/GND/P9/P10 disconnected: 196nA
Sleep current with nRF VCC/GND/P9/P10/P11/P12/P13 disconnected: 110-112nA
Sleep mode with ONLY Arduino: 110-112nA
NRF plugged into VCC/GND only: 800-900nA

At this point we are getting 2.7-2.9uA with Arduino/NRF. Stock MySensors library and Arduino 1.0.6 IDE. ( I am using the BinarySwitchSleep Sketch from MySensors lib)

To get even lower power....

Open up mysensors.cpp with NotePad++ application
Look for this code:

``````bool MySensor::sleep(uint8_t interrupt, uint8_t mode, unsigned long ms) {
// Let serial prints finish (debug, log etc)
bool pinTriggeredWakeup = true;
Serial.flush();
RF24::powerDown();
attachInterrupt(interrupt, wakeUp, mode);
if (ms>0) {
pinIntTrigger = 0;
sleep(ms);
if (0 == pinIntTrigger) {
pinTriggeredWakeup = false;
}
} else {
Serial.flush();
}
detachInterrupt(interrupt);
return pinTriggeredWakeup;
}
``````

We are going to add this code:

``````SPI.end();
for (byte i = 9; i <= 13; i++)
{
pinMode (i, OUTPUT);
digitalWrite (i, LOW);
}  // end of for loop
``````

The final code should look like this:

``````bool MySensor::sleep(uint8_t interrupt, uint8_t mode, unsigned long ms) {
// Let serial prints finish (debug, log etc)
bool pinTriggeredWakeup = true;
Serial.flush();
RF24::powerDown();
attachInterrupt(interrupt, wakeUp, mode);

SPI.end();

for (byte i = 9; i <= 13; i++)
{
pinMode (i, OUTPUT);
digitalWrite (i, LOW);
}  // end of for loop

if (ms>0) {
pinIntTrigger = 0;
sleep(ms);
if (0 == pinIntTrigger) {
pinTriggeredWakeup = false;
}
} else {
Serial.flush();
}
detachInterrupt(interrupt);
return pinTriggeredWakeup;
}
``````

IMPORTANT: Because you are ending SPI, you will need to call the sensor at the beginning of your loop to reinitialize the NRF

``````void loop()
{
sensor_node.begin();
``````

Adding both SPI.end(); and for(); loop:
Sleep current: 1.5uA

If you add just the SPI.end();
Sleep current: 2uA

If you just add the for(); loop:
Sleep current: 1.9uA - 2.2uA

• If you are using ONLY the "for(); loop", you do NOT need to reinitialize the radio when you come out of sleep. I have noticed a much longer up time when having to reinitialize.

OTHER MEASUREMENTS using the DallasTemperatureSensor with WDT at 30 seconds, no sensor connected:

Edited Sleep with for(); loop:
Sleep current: 6.4-6.5uA

Edited Sleep with for(); loop AND SPI.end();:
Sleep current: (Could not get SPI.end(); to work on sleep(w/WDT))

Quick comment: There are a few sleep options in the MySensors.cpp Depending on which one you are calling will depend on which one you need to edit. Here are some examples of the sleep functions in the .cpp file:

``````void MySensor::sleep(unsigned long ms)
``````
``````bool MySensor::sleep(uint8_t interrupt, uint8_t mode, unsigned long ms)
``````
``````int8_t MySensor::sleep(uint8_t interrupt1, uint8_t mode1, uint8_t interrupt2, uint8_t mode2, unsigned long ms)
``````

• @brolly759 said:

When running everything I get these sleep numbers:
oState: 23-24uA
cState: 117uA

I downgraded my Arduino IDE from 1.6.5 to 1.0.6 and here are my new numbers:
oState: 2.5-2.7uA
cState: 98-100uA

Nice write-up!

Is it known why there's a difference in the measurements depending on whether you're using IDE 1.6.5 or IDE 1.0.6? Which IDE version should I use?

• Someone else complained about the exact same issue here:
http://forum.mysensors.org/topic/1345/sensebender-micro/250

• @brolly759 That's a different issue altogether. It's related to measuring battery voltage...

Cheers
Al

• @Sparkman said:

@brolly759 That's a different issue altogether. It's related to measuring battery voltage...

Cheers
Al

tlund posted 2 months ago reply quote 0
@tbowmo

My NRF's are the same \$1 nrf's listed in the mysensors store, so probably fake. But I have still measured them to draw ~900nA in powerDown.

But I think I have found the culprint now. It seems the extra 20uA is caused by Arduino 1.6.5 (it may be that my installation is faulty).

My test setup:

pro mini
nrf
a simple sketch that does gw.sleep(60s)
1st test: sketch compiled & uploaded via Arduino 1.0.5-r2: 6uA
2nd test: sketch compiled & uploaded via Arduino 1.6.5: 24uA

• @brolly759 Sorry, I was confused as your link is to post 250 in that thread, which is my post related to measuring battery voltage. What you are referencing is post 191: http://forum.mysensors.org/topic/1345/sensebender-micro/191

Cheers
Al

• @Neverdie : at the beginning, as you were suspicious about the fact I get it. You can see here (look at the dates) that I had problems with low power and Charles helped me.
It's in french sorry : https://community.hallard.me/topic/53/question-Ã -propos-du-bod/30
At the same time I opened a thread on arduino forum : http://forum.arduino.cc/index.php?topic=336789.0
Another older topic that I solved myself (which contains some part of codes I was testing) : http://forum.arduino.cc/index.php?topic=336329.0
I hope you trust me now. and that I cannot I give a cake which is not finished cooking. I am not hurry. And I prefer the whole thing well packed in a lib, with derivative class, because the less the Mysensors libs are hacked inside, more beautiful it is I think. And then it is easier for users too.

@brolly759 : thank you for writing you results as I have no time for this on my side. Very strange your problem with ide. When I got low power, I was using ide 1.6.0. Maybe I will try 1.6.5 this week end to see, for curiosity. And I know Charles is using 1.6.x too. Another question, is your sensor a binaryswitchsensor only?? In this case, your way makes sense. But if you want to add sensors, you won't be able to keep 1uA without mosfet I think. Maybe I am wrong and you will find a great idea...

• @scalz said:

@Neverdie : at the beginning, as you were suspicious about the fact I get it. You can see here (look at the dates) that I had problems with low power and Charles helped me.
It's in french sorry : https://community.hallard.me/topic/53/question-Ã -propos-du-bod/30
At the same time I opened a thread on arduino forum : http://forum.arduino.cc/index.php?topic=336789.0
Another older topic that I solved myself (which contains some part of codes I was testing) : http://forum.arduino.cc/index.php?topic=336329.0
I hope you trust me now. and that I cannot I give a cake which is not finished cooking. I am not hurry. And I prefer the whole thing well packed in a lib, with derivative class, because the less the Mysensors libs are hacked inside, more beautiful it is I think. And then it is easier for users too.

@brolly759 : thank you for writing you results as I have no time for this on my side. Very strange your problem with ide. When I got low power, I was using ide 1.6.0. Maybe I will try 1.6.5 this week end to see, for curiosity. And I know Charles is using 1.6.x too. Another question, is your sensor a binaryswitchsensor only?? In this case, your way makes sense. But if you want to add sensors, you won't be able to keep 1uA without mosfet I think. Maybe I am wrong and you will find a great idea...

@Scalz Not sure what you're referring to. I've taken what you've said at face value and still do. For the moment, if you are willing and able, it would help Broly759 and me if you would replicate Brolly759's approach (as he detailed above) and see if you can figure out why the IDE version is affecting his measurements. Which measurements are "correct"? Is that something you can help us figure out?

It would be best if we could all use the latest version number when taking measurements, unless there is good reason not to. I'm currently running IDE Version 1.6.5., and to date I haven't had problems with it. I did have some compile-time problems with some of the earlier Version 1.6 releases prior to the 1.6.5 release, but I don't recall now exactly what those problems were.

• ok, I hope I will have enough time this week end because this week I have lot of work too, and Mysensors is jut fun for me. and I am running after time. It doesn't take time to reply for me, more for testings.. but I promise I will try the writeup. And I am trying to create my startup in greentech (automotive, cogeneration.. field) field. So most of my time is dedicated to my project. But I like playing too with arduino, so fun!

One thing I am sure, is when I got 140nA, it was BinarySwitch sketch too, from 2xaaa, ide 1.6.0. Then I added a BS250, to cut off nrf. And I got 140nA again in sleepmode. No problem, for sleep/wake up radio. And of course, I made the same tricks as Brolly in code. But maybe I had luck because I powered it through mosfet. Then I made same thing, BS250, for sensors, and uses BH1750 sketch. I had trouble with i2c. Charles helped me and then I got 140nA again. No problem with radio, sensors... All of this directly from 2xaaa. Then I played with boosters...
I will try brolly's case too, to see if I get same thing.
@brolly759 : you are using an arduin pin to power your nrf, am I right? to be in the same config as yours...

• GOOD MORNING crazy tinkerer's. Okay here we go again, I am actually going to need someone to verify what I am looking at here, nA and uA are giving me different readings:

Running the "for(); loop" in sleep() function with NRF VCC UNPLUGGED
Sleep current: .8uA - .9uA OR 273nA

Running the "for(); loop" in sleep() function with NRF VCC UNPLUGGED
Sleep current: .6uA - .9uA OR 114nA

@scalz I was powering the NRF directly from VCC. I will play around with connecting it directly to a pinOut on Arduino

• OKAY so... more numbers to play with... This is Arduino turning on/off NRF using an output pin.

• Connect Pin4 to VCC on NRF

• Add SPI.end(); and for();loop to include Pin 4 to turn LOW in sleep function

Add this code in define area:

``````#define WIRELESS_POWER 4
``````

``````void loop() {
digitalWrite(WIRELESS_POWER, HIGH);
delay(5);
sensor_node.begin();
``````

Sleep current oState: .5uA - .6uA
Sleep current cState: .8uA - .9uA

@scalz Yes all my testing is on "binaryswitchsensor" sketch. I use the "DallasTempSensor" sketch when I want to test sleep() with a timer. There are SO MANY things you can do with a simple reed switch sensor. Doors, locks, windows, mailbox, fridge, cabinets, drawers... pretty much anything that moves and goes back in a certain place can be used with the "binaryswitchsensor".

• @brolly759 When taking your measurements, were you using the current version of the MySensors library (v1.5) or a different one? Are all your other libraries the most up-to-date versions?

You used a Nano Pro, which I don't have. When the red Mini Pro's from Amazon arrive sometime later today, I'll try them.

Unless someone knows of a reason for the different results relating to different IDE versions, I think I will approach this by calling the underlying libraries directly, rather than through MySensors's abstraction layer. That way, if I don't encounter the differences, we'll know that it's a MySensors issue. For example, perhaps something you're setting is being undone by MySensors part way through the process of powering down, or something like that.

• @brolly759 : I am happy for you. I was thinking that you were trying to make a sensor node (not only for binaryswitch). I agree with you for binaryswitch.. I think how you do is right for this purpose. cool. just one thing is with time, your coin cell will not provide full 3v for radio power transmission but it's another story.

See you soon.

• @NeverDie Good catch, I just checked the version.h file. v1.4.1

``````#define LIBRARY_VERSION "1.4.1"
``````

In the utilities folder in MySensors library, all the files like RF24.h, LowPower.h are provided by the MySensors library. So I am assuming they were up to date when the MySensors library was created.

@scalz Even though its not full 3.3v it should be fine. The power range for NRF is 1.9v - 3.6v

My next project is to figure out battery monitoring as low as possible. I know there are 2 ways, internal 1.1v reference or voltage divider. Can I do a voltage divider on an output pin and shut the output pin off when not using it?

• @scalz said:

@brolly759 : I am happy for you. I was thinking that you were trying to make a sensor node (not only for binaryswitch). I agree with you for binaryswitch.. I think how you do is right for this purpose. cool. just one thing is with time, your coin cell will not provide full 3v for radio power transmission but it's another story.

See you soon.

Actually, your point regarding the coincell not providing full power could be relevant to the measurements (not saying it is in brolly759's case, but I definitely have seen it myself happen with a coincell powered arduino using the NRF24L01+): in cases where the coincell is low, doing a transmission can (because of internal resistance and the much higher current) can cause NRF voltage to drop below threshold, thereby shutting off the radio (not just sleeping it), which would obviously throw off the current measurement. Definitely something to be aware of.

• This is so frustrating, you know that?

So I reseated my cables to make sure I am getting the best connection. Now my current is the last configuration is:

sleep current oState: ~105nA
sleep current cState: ~457nA

@NeverDie my 2 AA battery setup right now are @ 3.452v

• I recommend you don't use a coincell while testing. Use a big enough battery so that you won't be getting flakey results.

• @NeverDie my 2 AA battery setup right now are @ 3.452v

• @brolly759 said:

This is so frustrating, you know that?

So I reseated my cables to make sure I am getting the best connection. Now my current is the last configuration is:

sleep current oState: ~105nA
sleep current cState: ~457nA

@NeverDie my 2 AA battery setup right now are @ 3.452v

In a way this might be good news. Perhaps something similar was causing the difference in your earlier measurements and not the different IDE versions?

I've had similar happen to me. Epecially because of plugging/un-plugging arduino's to modify programming jostles the wires or otherwise loosens connections, and then suddenly your measurements change for no apparent reason. Sometimes it can takes a while to figure out that's what's happening.

The NRF24L01+ is well known to be very sensitive to loose connections--a lot more than other radios. If you can solder your connections, definitely do!

In fact, it's so sensitive that even just running your supply and ground lines to the NRF close to the data lines can cause serious problems as well! Keep them as far aspart as you can. It's an unusually touchy radio.

• I just upgraded to Arduino IDE 1.6.5:

Board: "Arduino Pro or Pro Mini"
Processor: "Atmega328 (3.3V, 8MHz)

Sleep current: 19uA.

Using previous IDE I was @ 100nA.

Here is the sketch I am using:

``````#include <MySensor.h>
#include <SPI.h>

#define SKETCH_NAME "Binary Sensor"
#define SKETCH_MAJOR_VER "1"
#define SKETCH_MINOR_VER "0"

#define PRIMARY_CHILD_ID 3
#define SECONDARY_CHILD_ID 4

#define PRIMARY_BUTTON_PIN 2   // Arduino Digital I/O pin for button/reed switch
#define WIRELESS_POWER 4

MySensor sensor_node;

// Change to V_LIGHT if you use S_LIGHT in presentation below
MyMessage msg(PRIMARY_CHILD_ID, V_TRIPPED);

void setup()
{
pinMode(WIRELESS_POWER, OUTPUT);
digitalWrite(WIRELESS_POWER, HIGH);
sensor_node.begin();
pinMode(PRIMARY_BUTTON_PIN, INPUT);

// Send the sketch version information to the gateway and Controller
sensor_node.sendSketchInfo(SKETCH_NAME, SKETCH_MAJOR_VER"."SKETCH_MINOR_VER);

// Register binary input sensor to sensor_node (they will be created as child devices)
// You can use S_DOOR, S_MOTION or S_LIGHT here depending on your usage.
// If S_LIGHT is used, remember to update variable type you send in. See "msg" above.
sensor_node.present(PRIMARY_CHILD_ID, S_DOOR);
}

void loop()
{
digitalWrite(WIRELESS_POWER, HIGH);
delay(5);
sensor_node.begin();

uint8_t value;
static uint8_t sentValue=2;

sensor_node.sleep(5);

if (value != sentValue) {
// Value has changed from last transmission, send the updated value
sensor_node.send(msg.set(value==HIGH ? 1: 0));
sentValue = value;
}

sensor_node.sleep(PRIMARY_BUTTON_PIN-2, CHANGE, 0);
}
``````

• I hope I won't see this difference too when I will retry with 1.6.5 (I tried with 1.6.0, and it was with Mysensors 1.4). otherwise I will move to Atmel studio...

• @scalz said:

I hope I won't see this difference too when I will retry with 1.6.5 (I tried with 1.6.0, and it was with Mysensors 1.4). otherwise I will move to Atmel studio...

@scalz Can you retry with both IDE 1.6.5 and MySensors v1.5 fairly soon? Of course, as you've explained, I realize you have other commitments.... It just would help a lot if we're all on the same page.

• I am using v1.6.5. I burned the bootloader for Pro Mini, still no change.
Sleep mode: 17.9uA

FYI, when upgrading from v1.4 to v1.5 of MySensors lib, DO NOT overwrite all the files, Delete the folder, add the new v1.5 I had a lot of errors just now

I switched to v1.5 with v1.6.5 and I am getting 2uA in oState now. Now I am trying to play with the new sleep settings. will give an update soon.

• The new sleep library is all over the place and I cannot make heads or tails of it.

I am using IDE 1.6.5 and MySensors v1.5 and I am getting 2uA in sleep mode with my modified BinarySensorSwitch sketch.

I want to be able to shutdown the radio pin and LOW all the pins but I don't know where to add it. Anywhere I add, the radio stays high forever basically. Any idea's?

• Notionally, I should think it would fit well as a subclass of the RF24's powerDown method.

• ``````void RF24::powerDown(void)
{
ce(LOW); // Guarantee CE is low on powerDown
digitalWrite(4, LOW);
``````

No matter where I put it... the NRF will not fall back asleep. It stays @ 4mA

• @brolly759 said:

I am using IDE 1.6.5 and MySensors v1.5 and I am getting 2uA in sleep mode with my modified BinarySensorSwitch sketch.

I want to be able to shutdown the radio pin and LOW all the pins but I don't know where to add it. Anywhere I add, the radio stays high forever basically. Any idea's?

Does your wiring change at all when you switch from the first scenario to the second? I'm guessing that in the first scenario you're powering the radio through vcc, but in the second you're powering it through a pin (what you're calling the "radio pin" and which you intend to set LOW in order to turn-off the NRF rather than "power down" sleep it). Is that right?

• Correct, I was able to use radio pin to shut it off (pin 4) manually in v1.4 library. I cant inject the code in v1.5. If I can put the code in the sleep function somewhere, it is not easy to find anymore.

• You'll find the radio sleep call for NRF24L01 in MyTransportNRF24.cpp.

https://github.com/mysensors/Arduino/blob/master/libraries/MySensors/MyTransportNRF24.cpp#L92

• No idea why but every so often I have to uninstall Arduino, delete the libraries and basically start over. Getting frustrating and I might go back to 1.0.5 + v1.4 lib.

• Subsequent to yesterday I ran Gammon's "Sketch J" on the very same Pro Mini that I had started this thread with (the one where I had soldered on 30 headers and which was drawing 17.2uA in the previous attempt at sleep with no watchdog timer). Instant results! Sleep current dropped to 125nA. I used a uCurrent Gold in conjunction with a Fluke 87V to take the measurement. That number is in good agreement with the 150nA reported by Gammon himself for a barebones arduino build. And, by the way, yes, I am running the current Arduino IDE 1.6.5 and the current libraries.

Ridiculously easy! As before, it's just 3 steps. For the third step, just use Gammon's sketch to put your Pro Mini into sleep powerDown. Easy! Don't bother with RocketScream or LowPowerLab sketch and library. Leave them out of it.

More good news: you already have the library Gammon's sketch uses--it's avr/sleep.h, so if you want to replicate this measurement test for yourself you won't need to download or install anything other than Gammon's sketch itself. You can find "Sketch J" here: http://www.gammon.com.au/power

As far as I'm concerned, this proves the Pro Mini is a perfectly viable low power platform. This particular measurement test was my due diligence before standardizing. Therefore, I'm done here.

Good luck to each of you on your various low power pursuits.

• @Neverdie: I am so happy for you! you know what I mean now about those easy steps. it is very strange that I had difference with lowpowerlab. I have looked at the lib and saw the part about the powerdown but I am not familiar with this syntax yet. I prefer how sketch J looks. But I was so happy when I saw this <uA, lol!
but I can't wait to see Charles' ulpnode lib. He told me that it would be Mysensors compatible. it makes more sense now with new organization of Mysensors lib. great work @Hek and mysensors team! Mysensors is so fun ahahah! I am addict!

• @NeverDie I never had issues with Gammon's code on v1.6.5 . I had issues with the mysensors v1.4 library with v1.6.5 of Arduino IDE. My power problems went away when I switched to v1.5 of mysensors library. I have stopped troubleshooting for now as I am slightly burnt out but my last test on v.1.6.5 with v1.5 MySensors gave me strange results sometimes. If I edited any files in the sleep mode functions I would not be able to go back to sleep. I was draw a constant ~3mA.

Congrats though and welcome to the club. I think I am going to just combine nRF Mesh + gammon's code to make my own mesh network setup. (When I actually know programming)

• Does everything which is turned off in Sketch J automatically get turned on again during wake-up? Or, does it remain off? I notice that Sketch J repeats turning everything off again before going to sleep, each and every time. There are some things which I may not being using, like I2C and ADC, which it would make sense to leave turned off. Likewise, no reason to wakeup SPI on every 8 second cycle unless there's a reason to use the radio.

Furthermore, it would save valuable time at higher currents not needing to turn them off again. Anyone happen to know, or will I need to run experiments?

• By the way, perhaps a good argument in favor of an external interrupt for waking up is that it could wakeup the arduico and the radio in parallel. If the arduino wakes itself up through WDT and subsequently wakes up the radio, then it has to waste time waiting at high currents while the radio wakes up.

Just a thought at present, as I don't know how feasible this would be.

• In case anyone is curious as to what happens when an Arduino is waking up from sleep, this picture tells the story:

I powered an 8Mhz Pro Mini using a 5.1V battery (because it was convenient), and set it using "Sketch I" to wake up every 16ms and then immediately go back to sleep. The picture shows the Pro Mini draws about 500uA for about 2.1ms, then it surges up to about 6.5ma (I suppose at this point it is "awake"), and then voltage plummets back down again as it returns to sleep. When asleep it draws about 3.5uA. I measured the current using a 1ohm sense resistor, so in the picture 1mv=1ma. When measuring milliamps, I seem to get a much clearer picture (less noise) using a 1ohm sense resistor than I do using the UCurrent Gold.

In his write-up, Gammon warns that, depending on the sleep duration, this warm-up period can be as long as 65ms!

Various fuse settings make a big difference to the wake-up time. Some wake-up times are quite long (eg. 65 mS) because they are designed to allow the crystal clock to settle. If you are trying to save power, taking 65 mS to wake up, add 1 to a counter, and go back to sleep, is a lot. You would want to look at a "wake-up" fuse setting that is appropriate for the type of clock source you are using."
I wish he had been more clear about how the sleep settings affect the length of the wake-up period. Perhaps he or somebody else explains that elsewhere.

• @Neverdie: hi. you are doing interesting tests. for the question about 65ms.. I am not sure. I think Gammon was referring about the CKSEL fuses, oscillator config fuses. it is described in datasheet from 8.2.2.

• Hello guys,

I'm reading your post, and that is amazing... you're fighting with u/nAmps.

The lowest what I can get with Atmega328 + NRF24 on breadboard is 1mA.

What I've done:
Flashed Atmega328p with ATmegaBOOT_168_atmega328_pro_8MHz.hex
Uploaded BinarySwithchSleepSensor sketch with FDTI. Tried: API 1.4/1.5, IDE 1.0.6/1.6.5 (no difference)
Powered the sensor directly with 2xAA
Changed ext fuses to x07 (no BOD)
Connected NRF24 according to MySensors instructions

On the breadboard I have only:
Atmega328p
NRF24
10k resistor on 1st/reset pin.

With this set up minimum what I can get is:
Atmega328p w/o NRF - 3pin con - 0.1mA /not con - 3.4mA
Atmega328p with NRF - 3pin con - 1.09mA /not con - 1mA

I'm using cheap multi-meter, however, with Gammon's J sketch - it shows 3uA without NRF.

I'm struggling almost a week, and can't understand, why you guys achieving such a great results while using almost the same setup (Mini 8Mhz is based on Atmega328p).

• Hello @engy :

I have approximately same results as @brolly759.
I spent some times to reproduce due to a measurement issue but I am under uA with pull-up resistor of 10Mo.

David.

• My problem was defected NRF24 radios. Had to order 3rd batch from ebay, and even though it contained a few defected modules.

• @engy Hello. It's why I am using RFM69 as there is no fake

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