Hello, I want to open my car keyless and buton-less, if you know what I mean..
I've been using a bl module to do that for a while(testing-period) and it is clear that this method is very complicated, drains a lot of current from my car's battery and take a lot of time before it actually detect my phone(and my family ones) and unlock the door.
I gave up on this after 3 months of trying to do it :o
Now i'm thinking using an arduino pro + 433Mhz module + li-ion 900mAh bat with a charger module to unlock my car like I said
Without even pressing a button.
I'm thinking of connecting the pro directly to the battery module (so no current will be lost because of shit regulators) and put it in a nice key chain.
About the software I thought I could put the pro to sleep, and every 2 seconds to wake up fast and send a signal(btw, I will attach no antenna to this rx, tx modules because I don't want a more then 3m range)
I didn't really calculate how much I can run my keychain with a charge but here comes the second problem(beside keychain battery drain), my car battery!
On my old project(with the bl module) my arduino wakes up every 4 seconds and 2 seconds he was scanning for my bl, but using rf signals I need to keep my arduino MEGA fully wake up and be able to hear the keychain everytime.
This will be very current consuming for my car(considering the general battery drain of almost any car is around 15mA, with my arduino fully wake up it will be at least +150%, too bad >:(
Somehow I need to power them in the same time, so the signal meets the wake up time from my arduino, but I think this is impossible...
Or maybe I can use a low current real clock on both arduino tx and rx to send a signal every odd second
So... What do you think?
Here is everything you need to know: https://www.gammon.com.au/power
I'm surprised that bluetooth ran down the car's battery. After all, it isn't usually a big drain on your phone's battery.
Is it really so bad to have to use a button? And there may be occasions when you're near your car and DON'T want it unlocked....
Allan
allanhurst:
Is it really so bad to have to use a button? And there may be occasions when you're near your car and DON'T want it unlocked....
Allan
Then, where is the magic? 
MorganS:
Here is everything you need to know: Gammon Forum : Electronics : Microprocessors : Power saving techniques for microprocessors
I'm surprised that bluetooth ran down the car's battery. After all, it isn't usually a big drain on your phone's battery.
Thanks for the link, i'll do as much as possible from those methods to lower my current drain on my key chain, but still, I need to sleep them both and their wake time may not meet each other, and the signal from the transmitter will not reach the car's arduino receiver every time.
Am I right?
OK.....
the receiver on a car's remote takes about 5mA continuous . With a 40AH car battery it'll takes months to make any significant dent in that. Just leave it on.
The remote - suppose it runs for 1/10 second every 10 seconds... that's 1/100 duty cycle. If the transmit takes 5mA, this is an average drain of 50uA.
A CR2032 battery ( 220mAH) would last > 4000 hours - about 6 months.
Not too bad.
All you then need is a standard car remote with a CMOS 555 running at 1/10 Hz with a 1/100 duty cycle to drive it ....
Remove it's little LED if fitted - a waste of power.
You then need to modify the receiver such that if it doesn't receive a code for eg 20 seconds it locks the car.
Modern 'walking code' transmitter/receivers won't work, as the code will change too many times between accesses if you're not in range.....
Allan.
allanhurst:
OK.....
the receiver on a car's remote takes about 5mA continuous . With a 40AH car battery it'll takes months to make any significant dent in that. Just leave it on.
The remote - suppose it runs for 1/10 second every 10 seconds... that's 1/100 duty cycle. If the transmit takes 5mA, this is an average drain of 50uA.
A CR2032 battery ( 220mAH) would last > 4000 hours - about 6 months.
Not too bad.
All you then need is a standard car remote with a CMOS 555 running at 1/10 Hz with a 1/100 duty cycle to drive it ....
Remove it's little LED if fitted - a waste of power.
You then need to modify the receiver such that if it doesn't receive a code for eg 20 seconds it locks the car.
Modern 'walking code' transmitter/receivers won't work, as the code will change too many times between accesses if you're not in range.....
Allan.
Thanks for your reply!
First of all, the reason I abandoned the Bluetooth unlocking method it was because initialising it lasts 600ms, every scan lasts 2 s(for 3 phones) and I also need to include the sleep time, which was 2-4s too..
With a 3m range(because I cutted the bl antenna) I was waiting in front of my car, just to wait the scan to detect my phone.
This is why I want to move to rf signals, for faster response in the same 3m range(I suppose I can manage to make it 3m like I did with the bl)
I may use a cmos but currently I don't know nothing about it
Beside of this, the car isn't consuming only 5mA
Without any diy device it already consume 14, my arduino mega(even on3.3v) consume some(in wake up time at least 15mA) the regulator +3mA and the receiver +5mA so this is why I want to use sleep modes on my car's arduino
About the 20s time to lock the car, I think <10 will be enough, imagine how much you can travel from the car before it lock itself.