Hi everyone,
i'm looking after a low powered counter (at least until 100) able to send a wakeup signal to wake an arduino (by external interrupt) after 100 count (if it is customable) it is better.
It has to count signal 3.3VDC or 5VDC by changing state (high level to low level = 1 count)
The low powered characteristic while it will be used in a battery application
The minimal count while i don't need to wake up the arduino each count but only after 100 count in this case.
Could you advise me some electronic devices to achieve that if there exists?
Arduino and low power? Are you aware you need to get rig of all the power hungry default stuff first?
You can either use timer/counter 2 in asynchronous mode (but cannot use crystal for main clock) or an external counter. I have 74HC4520 but there are dozens of different counters and nearly any of them would work.
You get more help if you explain what you're trying to do.
Leo..
I try to count the "pulse" of a domestic gaz counter. Therefore sometimes there is a "pulse" each 30 second, sometimes there is no pulse during several weeks.
For the low power if the arduino is in deep sleep, it consumes only few µA. It's why i would like a counter to wake up each 100 counts to perform an action and put it again in sleep.
So if the counter requires few µA, this application can hold some months with batteries.
Must be 30+ years ago since I played with counters.
Google "binary counter" and "decade counter"
The first one divides by n^2.
Dividing by 64, 128 or 256 etc. is easier to do with a single chip.
The 4020 or 4040 (HEFxxxx, 74HCxx etc.), or 4060 comes to mind.
Or the 4017 for a decade counter (need two chips for /100).
Leo..
Again, what "Arduino" are you using so you are able to get few uA sleep current? AFAIK all Arduinos are power hungry and sleeping the main chip helps only a little. You must either use standalone chip or some "tweaked" board. If you are using ATMega chip running from internal RC oscillator there is asynchronous counter (Timer/Counter2) on the chip that is able to work with minimal power consumption (they say <1uA driving 32kHz crystal).
If you are using crystal/ceramic resonator for clock you may use nearly any 74HCxxx counter. Choose one that have outputs of stages you are interested in and can be clocked (and reset/preset) as you need.
One thing to be aware of when using CMOS gates/logic chips for micropower is that you must
tie all unused inputs to gnd or supply. This will guarantee sub micro-amp(*) current consumption
as opposed to many milliamps if an input happens to float into the forbidden zone.
Unclocked CMOS chips should consume only leakage current which is measured in nA.
Why can't the Arduino count? It can wake up for just a microsecond for each count and add it to its total. That's the kind of job the hardware designers at Atmel designed it for.
MorganS:
Why can't the Arduino count? It can wake up for just a microsecond for each count and add it to its total. That's the kind of job the hardware designers at Atmel designed it for.
There's a downside to that. That majority of AVR Arduinos use the Low Power Crystal Oscillator setting. It takes 16,000 clock periods for it to wake up from Power-down or Power-save modes, which is 1 ms @ 16 MHz. It's a millisecond of wasted power every time you wakeup.
It's much less of a problem if you use the internal 8 MHz oscillator, which takes only 6 clock periods to start up from sleep (750 ns).
MorganS:
Why can't the Arduino count? It can wake up for just a microsecond for each count and add it to its total. That's the kind of job the hardware designers at Atmel designed it for.
IMHO it is NOT designed to work as HW counter. It will be very poor in every aspect compared to it. Frequency is very limited, it is hard to guarantuee no event is missed, power consumption is higher...
But since the pulses are so slow (maximum once per 30s based on post #5) it does not matter and power consumption will be negligible in either case. So adding the HW counter helps little. But if the frequency were in order of kHz or even higher the counter would be a good choice.
Jiggy-Ninja:
It's a millisecond of wasted power every time you wakeup.
So what? Even if you wake up every 10 seconds which is more often than your indicated worst case (30 seconds) you have an equivalent current draw of 1 microamp (in addition to the sleep current draw of 1 microamp). Even two coincells (2032) with about 200 mAh will last more than 10 years with this
[EDIT] just consulted the data sheet: sleep current is much less than 1 microamp