prologikus:
Some Bmw key have it audi opel but can't find any info about their ics
Cars do not need low current receivers.
They have batteries with a typical capacity of 60,000mAhr + that is kept fully charged.
srnet:
Cars do not need low current receivers.They have batteries with a typical capacity of 60,000mAhr + that is kept fully charged.
Is not about the car, is about a keychain with a low li-ion battery of 1500mah, which needs to have a very low or none receiver of at least 2meters.. It isn't necessary to be a unique signal/message because this will wake up the arduino with will emit a custom 433mhz signal back to the car
Hi, I'm currently use a homemade keychain containing of an :
An -Arduino Nano (leds,regulator removed)
-A li-polymer battery 1800mAh
-A 433mhz transceiver (XY-FST)
-A step up converter (led removed) Link to close-up image
(no datasheet found for this step up conv chip)
And i'm using this code:
#include <VirtualWire.h>
#include "LowPower.h"
const int transmit_pin = 12;
void setup()
{
vw_set_tx_pin(transmit_pin);
vw_set_ptt_inverted(true);
vw_setup(2000);
}
void loop()
{
vw_send("G3o", 3);
LowPower.powerDown(SLEEP_500MS, ADC_OFF, BOD_OFF);
}
to emit a message every 500ms (this interval is the maximum interval for my project !)
The problem i face is that the battery is draining too fast, i know it's normal BUT,
What i can do to improve the battery consumption, what components to replace ? WITHOUT chaning the message or the inverval of the message!
You have been around long enough now to know not to double post.
This is the same problem as in your other Thread.
I am suggesting to the Moderator to merge them.
...R
Threads merged.
What i can do to improve the battery consumption, what components to replace ? WITHOUT chaning the message or the inverval of the message!
Get a bigger battery.
prologikus:
....but the receiver on my key chain can't be a simple 433mhz module receiver: it's consuming too much power...
googling
wake from sleep radio arduino
yields this link Wake up arduino from RF message - Project Guidance - Arduino Forum, in which post #13 describes a way that your battery-powered key chain's 434 MHz receiver and its Arduino could be sleeping most of the time, and then be awakened by a transmission from your door lock device (which presumably has no power limitations).
The radio needs to be on, but the Arduino can be sleeping. Maybe that's still not low enough power consumption.
Attach key chain Arduino's interrupt pin to pin 7 on the LM358 of the 434 MHz receiver (and connect the grounds)...
I've never tried this but have a project in mind that needs this capability. Now, if only I can tick off enough tasks on the other "to-do" list...
Follow-up: hmmmm... well, that post says the radio consumes 3.5 mA when on (and a sleeping Arduino's draw is tiny compared to that) so you wouldn't get more than three weeks of operation with a 1800 mA-hr battery. Oh well.
DaveEvans:
The radio needs to be on, but the Arduino can be sleeping.
It is probably not necessary to have the radio on all the time either. Imagine that the radio listens for 5 millisecs every 50 millisecs and the car transmits for 100 millisecs 3 times per second repeating a 5 msec message 20 times. The radio should always hear the message from the car but the radio is only active for 10% of the time.
...R
DaveEvans:
googlingwake from sleep radio arduino
yields this link Wake up arduino from RF message - Project Guidance - Arduino Forum, in which post #13 describes a way that your battery-powered key chain's 434 MHz receiver and its Arduino could be sleeping most of the time, and then be awakened by a transmission from your door lock device (which presumably has no power limitations).
The radio needs to be on, but the Arduino can be sleeping. Maybe that's still not low enough power consumption.
Attach key chain Arduino's interrupt pin to pin 7 on the LM358 of the 434 MHz receiver (and connect the grounds)...
I've never tried this but have a project in mind that needs this capability. Now, if only I can tick off enough tasks on the other "to-do" list...
Follow-up: hmmmm... well, that post says the radio consumes 3.5 mA when on (and a sleeping Arduino's draw is tiny compared to that) so you wouldn't get more than three weeks of operation with a 1800 mA-hr battery. Oh well.
Robin2:
It is probably not necessary to have the radio on all the time either. Imagine that the radio listens for 5 millisecs every 50 millisecs and the car transmits for 100 millisecs 3 times per second repeating a 5 msec message 20 times. The radio should always hear the message from the car but the radio is only active for 10% of the time....R
I appreciate your replys but it's more about the transmitter(emitter)...
Dave evans you can look to my reply 22.
The current setup consume less then having a receiver on my keychain and use wake up method from the first op-amp stage because the op amp itself consume a lot of power compared to sending a message every 500ms.
And even if the op amp wont use that much current, there are a lot of false triggers which will wake up the keychain and make it transmitt the message so a lot of power will be lost.
Because this thread was merged people won't read my #22 post, which is all you need to know about it.
In this old thread i was thinking to use another ic that will wake up my keychain in order to make it send the message and identify.
You may want to know..." To identify where? Why you, prologikus, don't tell us all the story? All the idea? "... Because this will lead to talking about the idea itself and not about how yo make the current idea more efficiency in terms of battery usage.
As an example i was expecting to hear this kind of staff from you, use another converter or use a regulator with 2 batterys
OR use another arduino
OR use another 433 mhz emitter(nameing it)
OR use this ic ( a ic that fits my requirements)
I don't know much about those things.... About what devices/ics should i use, i only grabbed what i already have in my drawer and use it...
I did not read everything but:
Do you know which part of the system consumes most current? You should check average consumption of the Arduino, DC-DC converter and TX and replace/tweak the one which eats the most current. Also how low power consumption do you expect? I would try nRF24L01+. According to specs you should be able to get average power consumption <100uA, no DC-DC converter needed (only LDO). The battery should hold for 2 years if my guesstimate is correct.
prologikus:
Because this thread was merged people won't read my #22 post, which is all you need to know about it.
Why did you screw up your Original Post. IIRC it was the same as your Reply #22 - which is WHY the Threads were merged. Screwing up older Posts makes a Thread very hard to follow.
I appreciate your replys but it's more about the transmitter(emitter)...
IMHO you need to change your mindset and make the car the transmitter because it has a huge battery.
...R
Robin2:
IMHO you need to change your mindset and make the car the transmitter because it has a huge battery....R
Tnx for your reply!
the first scheme show how the current sistem is working
and the second one is how i suppose you mean by making the car as a transmitter
but in the end i'll still end up with battery drain on the key,
do you understand why ?
Is this correct?
prologikus:
but in the end i'll still end up with battery drain on the key,do you understand why ?
Is this correct?
If the key is close enough to the car for the car to get a response the unit in the car can greatly increase the interval between messages which should have the effect of reducing the demand on the key's battery.
All this complexity would be completely unnecessary with a key that has a push button or an RFID tag.
...R
AFAIK real "buttonless" car keys use (coin) batteries for some reason. I am not sure why but my key does not work when battery is too weak. I guess it is "only" because RFID is not secure enough?
Smajdalf:
AFAIK real "buttonless" car keys use (coin) batteries for some reason. I am not sure why but my key does not work when battery is too weak. I guess it is "only" because RFID is not secure enough?
It's true, for example i know a bmw from 2007 which have some sort of keyless entry like this:
The car send a signal whenever a person touch the doorfob and that signal wakes up the key and then the key send another signal to the car
But this is done just one time, after the car is unlocked there are no more signals that wakes up the key
The car won't lock itself when you get out and far away from it
I suppose there are systems that works with passive rfid tags even from 5+ meters
That kind of system would be the best for my scenario, even if it won't be that much secured because where i live and where i travel there are no 'car hackers'