Can you verify that the MCU can wakeup from low power sleep in a couple of milliseconds? Which MCU are you using?

Actually I didn't give that much thought, I will verify that. Thank you for pointing that out.

I am using pic16f616.

 

Designing IR detectors is a challenge. You start with an IR diode in series with a resistor, and improve it.

Firstly, ambient light will cause a quiescent current. If your resistor is high, the quiescent is less, but the voltage across the resistor saturates at your supply voltage, leaving no room for the signal to vary.

If the resistance is low, the quiescent current is high, but the resistor voltage doesn't reach your supply, and you get signal.

And a high resistance gives a higher voltage signal, while a low resistance gives a low voltage signal.

Now you can replace the resistance with an LCR circuit, tuned to 38 kHz. This blocks the quiescent current caused by ambient light.

How you do this though, is your problem. I tell ya, its given me headaches in the past.

 

Can you verify that the MCU can wakeup from low power sleep in a couple of milliseconds? Which MCU are you using?

I have done some test today, that's how I do it:

- set up a switch on pin change interrupt, internal pull up resister enable, switch is active low
- in software, on switch interrupt, toggle and LED
- measure the time between the switch input pull low to the time the LED turn on (pin goes high)
- it reads ~25uS

I believe that's the time from an interrupt to the MCU actually toggle an LED.

 

@bug13
Maybe something simple like this just to wake it up?

http://www.learningelectronics.net/circuits/infra-red-sensormonitor.html

 

I wondered if Maxim or LTC had something tweaked for this application. The internal reference is a nice plus.

Note that any of the methods discussed so far will generate some false positives because they do not qualify the incoming IR as being part of a valid IR remote signal. A 38 kHz trap would help, but even then there probably will be some errors. The good news is that it will take very little computing time to determine that it is a false signal and shut down everything.

ak

 

@bug13
Maybe something simple like this just to wake it up?

http://www.learningelectronics.net/circuits/infra-red-sensormonitor.html

I have tested this one, the range is too short. I am hoping to get the same distance as the Vashey IR Receiver.

 

I have tested this one, the range is too short. I am hoping to get the same distance as the Vashey IR Receiver.

I was afraid of that.
You might try a low power op amp and gain it up before detecting it. You could use one op amp for gain and the 2nd for the comparator - Then make the threshold adjustable.

 

Would you be ok in having to use two pulses to get the command across? I.e. the low power section will activate if 38khz is detected, wake up the cpu, and then the cpu will receive the second button to do the proper function?

 

Would you be ok in having to use two pulses to get the command across? I.e. the low power section will activate if 38khz is detected, wake up the cpu, and then the cpu will receive the second button to do the proper function?

The low power IR detection circuit is where I am hoping to get some help with. See my post #11

 

Just a little feedback on what I have done:

These are what I tried but failed:

• I have done some test similar to this: http://www.learningelectronics.net/circuits/infra-red-sensormonitor.html (point out by ronv on post #24), the circuit show is good for very short distance.
• I can get sensing distance to about 2-3 meters (still not far enough for my application) by amplifying the signal. But the current draw is too high for my application.
• Then I search for low power, low offset voltage and low bias current op-amp. I didn't find a suitable one, they are either draw too much current, or the GBWP is too low.

This works (for me):
Using MSP430, runing on LPM3, power the Vashey IR receiver on a duty cycle of about 7.6%. this drop my standby current from ~350uA to ~35uA (IR receiver + MCU). The duty cycle is limited by the slow response of the IR receiver module and the 9ms NEC IR protocol lead code I am using.

PS: the working distance is about 6-7 meters.

 

Hi!

I know this is a super old thread but I've got a product we're moving into the 2nd generation and need a super low power usage IR solution that will "wake up" the MCU. You seem like you know what you're doing and learned a lot. are you open for some consulting to help guide our engineers on what you found?

I'm Jamie <e-mail address snipped> Hope to hear from you!

MOD NOTE: Please respond here or PM Jamie if you think you can help.

Using MSP430, runing on LPM3, power the Vashey IR receiver on a duty cycle of about 7.6%. this drop my standby current from ~350uA to ~35uA (IR receiver + MCU). The duty cycle is limited by the slow response of the IR receiver module and the 9ms NEC IR protocol lead code I am using.

PS: the working distance is about 6-7 meters.

 

Hi!

I know this is a super old thread but I've got a product we're moving into the 2nd generation and need a super low power usage IR solution that will "wake up" the MCU. You seem like you know what you're doing and learned a lot. are you open for some consulting to help guide our engineers on what you found?

I'm Jamie <e-mail address snipped> Hope to hear from you!

MOD NOTE: Please respond here or PM Jamie if you think you can help.

Using MSP430, runing on LPM3, power the Vashey IR receiver on a duty cycle of about 7.6%. this drop my standby current from ~350uA to ~35uA (IR receiver + MCU). The duty cycle is limited by the slow response of the IR receiver module and the 9ms NEC IR protocol lead code I am using.

PS: the working distance is about 6-7 meters.

That was a project we done a long time ago, it was a success! Need more details about your project, but I think 6-7 meters is definitely doable. Have PMed you.

 

Hi, this project is exactly what I'm looking for! Can you share some details or maybe are you interested in a collaboration?

 

Hi, this project is exactly what I'm looking for! Can you share some details or maybe are you interested in a collaboration?

Send me a PM with your email, and we can go from there.

 

Hi, I just registered on AllAboutCircuts, so I don't have the needed 10 posts to start a conversation, can you start it?

 

Send me a PM with your email, and we can go from there.

I am also really interested in how you solved your problem because I am facing the exact same difficulties at the moment. Could you share some information (also over PM if prefered)?

Thanks in advance!