Dear Arduino experts,
I am a newbie. I need to make Arduino app as low power as possible. I would like to know it is possible to put Arduino to sleep all the time until an interrupt is raised. The sleep mode power consumption should be in terms of uA, not mA. May I know if that is possible?
May I know if that is possible?
Yes.
In that thread I got down to 100 nA (0.1 uA) whilst checking for key presses on a keypad.
Ok, after reading your link, I have a few questions and I'm hoping you'll see this and still be able to answer them.
You mention that a bare bones board has no Voltage Regulators or LEDs, and that just 3 "AA"s will power the controller just fine. Is all the extras the reason why it's recommended to use a 7-12V supply?
You also mentioned using the clock chip. I don't know much about clocks, other than I need one to keep time for my device. So, if I used a pin to power it, would it continue to keep the time when the pin is off since it has it's only battery? I take it, it just continues to count with the coin cell connected to it and when the MCU is powering it, your code translates the counts into Days/Weeks/Months/Years/etc.?
And lastly, since the VC0706 camera module I'm using has a sleep function and requires 5V to operate, I could then sleep the camera BEFORE sleeping the MCU and when a PIR is triggered, wake the MCU, then wake the camera, take a pic, then sleep both again to conserve a LOT of power?
I know it's been some time since this post has been made, but I'm hoping you'll still see it and be able to answer these questions. Thanks in advance.
Yes; the 5V and 3.3V regulators are the reason for the higher voltage required at the barrel jack. The USB/Serial chip and the power LED and the voltage comparator chip all draw power all the time.
Using a barebones setup with just '328P, 10K reset pullup, crystal, two 22pF caps, and 3 or 4 o.1uF decoupling caps, the power will be way lower in power down sleep mode, especially if steps are taken to turn off internal clock functions.
Use a p-channel mosfet to control power to your camera module - bring any outputs from the '328P low before turning off the camera power and then going into sleep mode - high outputs can be a power path into the camera.
RTC module will be powered by its coin cell backup battery to run time if the RTC power is removed when the camera power is removed.
On interrupt, your sequence sounds correct.
And there it is, #20,000 ...
Congrats, CrossRoads!
So, if I used a pin to power it, would it continue to keep the time when the pin is off since it has it's only battery?
The clock chip has a coin battery (CR2032) which helps it keep time even when unpowered. That is supposed to last 10 years.
And everything CrossRoads said.
Here is my temperature and humidity sensor:
That has very low power use, and does what CrossRoads said. It uses a MOSFET to turn on and off "peripheral" devices.
Thanks Nick. 3+ years of postings. I see you are getting up there too! Won't be much longer. Leo72 in Italy is close as well; Awol passed it a little while ago.
CrossRoads:
Use a p-channel mosfet to control power to your camera module - bring any outputs from the '328P low before turning off the camera power and then going into sleep mode - high outputs can be a power path into the camera.
Ok, but if I completely lose power to the camera, then all my settings are reset and the process of re-initializing it would start over again, correct? So, being able to take a picture as soon as motion is detected would result in a lot of pictures with nothing in it.
Wouldn't it be wiser to leave the "power pin" to the camera set to HIGH and just deal with the extra consumption? Or will leaving it HIGH(with the camera in sleep) damage the camera if the MCU is asleep?
I don't see why it would damage the camera.
Thank you. That info will come in handy. I started reading it last night, but then my internet went out. All your information on battery life and power usage has been amazing! Thank you so much for sharing that knowledge!
And leaving it HIGH while MCU is asleep would still provide power to it? Just so I'm on the same page.
Or would that be LOW? I can't remember if you said a P-Channel or N-Channel MOSFET. I haven't used one yet, but I get the basic idea behind it.
The pin levels don't change when the CPU is asleep.
Whether you leave it high or low depends on what you want it to do.
I was going to suggest an opto-isolator but that would use a few mA of current (to drive the LED in it).
The pin levels don't change when the CPU is asleep.
So, if I were to leave a pin HIGH and put it to sleep, that pin would stay HIGH?
I was going to suggest an opto-isolator but that would use a few mA of current (to drive the LED in it).
I have no idea what an opto-isolator is. Lol, I guess I'll be looking that up later.
xKoldFuzionx:
So, if I were to leave a pin HIGH and put it to sleep, that pin would stay HIGH?
That's what I was getting at, yes.
Sorry, was just trying to make sure I understood correctly. Good to know. Thank you.
Here is an opto-isolator. It is a way to control a remote device without plugging the device directly into the Arduino: Opto-isolator - Wikipedia
Yeah, as soon as you said that, I remembered reading about them before. Say for instance, you wanted to control your dishwasher remotely from the arduino. Also a safer way of running something with a MUCH higher voltage.
xKoldFuzionx:
Yeah, as soon as you said that, I remembered reading about them before. Say for instance, you wanted to control your dishwasher remotely from the arduino. Also a safer way of running something with a MUCH higher voltage.
Most opto-couplers aren't rated to handle the output voltage that high or A/C current. For something like a dishwasher, you want a real relay that is rated for the current in the line.
Ok. I can't imagine hooking my d/w up to a remote anyways, or any appliance for that matter, but I'll remember that.
Doesn't it have something to do with safely handling the voltage on the other end, though?
Or am I thinking of an opto-coupler? Are they different?