Ultra low powered timer

Logzy

Joined Jun 4, 2019
6
Hi Guys,
Been doing a bit of reading here but a first time poster.
Anyway I was wondering if i can get some help regarding a timer i need and with the discussion around the PIC10F322 is this the IC for me.??

What i need is a low power circuit than can run on a small battery for 3+ years. (Battery can be "C" size or "D" size lithium if needed.)
This circuit will be a timing circuit;
When a pressure switch (S1) closes the timer starts (T1).
When the programmed time (T1) is reached it will output (O1) to power a MOSFET SS Relay to close a contact (Trigger in a data logger)
If S1 opens before T1 is reached then the process is reset and starts over.
After xx time (T2) is reached it will stop O1 regardless of S1 state.
When S1 opens the circuit does nothing, waiting for S1 to close again repeating the process.
T1= approx 1min
T2= 3-5 mins.

This logic i know should be able to be done easily with the data loggers firmware however it is locked down and there is no other way other than a seperate circuit.
Hoping someone can assist.

crutschow

Joined Mar 14, 2008
25,256
Don't know if the micro will work, but you could use a CD4060 counter such as shown here, to generate the delays.
It will draw only leakage current when timing is inhibited.

AnalogKid

Joined Aug 1, 2013
8,536
Summary:
If S1 is closed for less than 1 min, no output.
If S1 is closed continuously for 1 min or more, 3 min output period starts
When output period ends, system resets
If S1 is closed during and after this reset, it must be released and re-pushed to start a new cycle

If all of that is correct, then ...

A low power PIC will do this with fewer parts than any other approach, but there is that software development thing. An all-hardware solution would be 2-3 CMOS chips and zero power between cycles. 1 CD4060 oscillator/counter, 1 2N7002 MOSFET for control circuit power, CD4093 quad NAND gate (output flipflop and other gating) and maybe 1 more for I-don't-know-what-just-yet.

What is the part number of the MOSFET SS Relay?

How many operation cycles per year?

ak

djsfantasi

Joined Apr 11, 2010
6,709
Just going to throw this in here. I’m just learning PICs, but I’m familiar with the Ardunio IDE. The IDE can program other microprocessors beyond those that may be in an Ardunio.

ATTiny45 for example. This single chip solution can be programmed in C with the Arduino IDE. You only need one input and one output. The ATTiny45 has up to 6 GPIO pins, so you’re good here. The chip is like ~$2 and the required USB programmer is like ~$17. Under \$20 fer sure.

A small C program giving you all the functionality you need must be written. Timer functions are built in to Arduino C, so programming your time delays are simple. No need to define timers, scale factors and counters.

crutschow

Joined Mar 14, 2008
25,256
No need to define timers, scale factors and counters

CharlesWMcDonald

Joined May 16, 2019
233
I recommend the PIC12F629/675. It is 8 pins, easy to program and is very low power. You can program it to go to sleep after the time out and it will wake from sleep when the pressure switch closes. During sleep the microcontroller only consumes a few nano amps.

djsfantasi

Joined Apr 11, 2010
6,709
As low as 0.1mA active. 4μA in sleep mode.

If the WDT (used in sleep mode) is used, the minimum supply voltage must be 3V versus 1.8V.

Logzy

Joined Jun 4, 2019
6
Thanks for all the replies, now im even more confused. lol.
As for which MOSFET SS relay, I dont know which one, anything suitable.
Cycles per year could be anything like 100-300 per day (S1 opening and closing)
For the actual activation of the SS relay (O1) lets say 10-15 times per day.

Incase it matters this will be housed in an enclosure and fitted to a truck.
It will be a tiny board or few connected and potted components where I will be looking at 50-100 for first order with quantities growing. (Again, dont know if this matters)

Dodgydave

Joined Jun 22, 2012
9,310
I would go with a pic on this for simplicity, and ideal for mass production,,
like the 12F675, or the new version of it PIC16F18313. This uses 40nA in sleep mode, voltage range 1.8V to 5V. In 8pin dil.

Last edited:

Logzy

Joined Jun 4, 2019
6
Thanks for the ideas and i really like the PIC16F18313 idea.
Im fast learning and will openly admit that this is a bit beyond me and I need to concentrate on other aspects of the project.
Originally i was going to use a TPL5111 and i could probable have managed this myself however this wouldnt allow me to turn O1 off after xx time.

This is something i need to give to someone or a company to develop for me.!

AnalogKid

Joined Aug 1, 2013
8,536
Super low power logic is relatively simple with today's components. The problem is the SSR. 15 times per day at 4 min each x 365 = 365 O1 hours per year, x 10 mA (SSR current) = 3.65 Ah, x 3 years = 10.95 Ah battery capacity at 3.3 V or 3.6 V. For lower SSR operating currents, reduce proportionally. This might work:

ak

Logzy

Joined Jun 4, 2019
6
Hi guys,
i really like the PIC16F18313 idea and was wondering if someone wanted to come up with a circuit and code for me.
This may not be the place to ask but there are alot of brains here that know what their on about.
I would be happy to do this as a paid project if anyone is interested. Id love to do it myself but its a bit beyond me and I need to concentrate on other aspects of the project and for someone who knows what theyre doing this is a nice on the side hobby job.
After some thought I have altered the operation slightly. This will give me more flexibility in the functionality where i can then change T1,T2&T3 in the code during testing. Code would need to be supplied so I can change values and test.
The circuit would run on a 3,0V lithium battery up to a "D" cell size 19000mah if required to give 4-5 years operation unless someone has a better idea.

Operation - Rev. B.
When a pressure switch (S1) closes the timer starts (T1).
When the programmed time (T1) is reached it will output (O1) to power a MOSFET SS Relay to close a contact (Trigger in a data logger)
This then starts T2 timer
If S1 opens before T1 is reached then the process is reset and starts over.
After programmed time (T2) is reached it will stop O1 regardless of S1 state.
When S1 opens after an O1 time out finishes T3 starts and the system does not respond to S1 for xx time.
T1= approx 1-2 min.
T2= 45 seconds.
T3= 10 minutes.

Hope i havent overstepped the mark here or offended anyone, hoping someone can help.
Id rather give this to someone to do than a large company if possible.

Cheers,

crutschow

Joined Mar 14, 2008
25,256
I assume the data logger trigger is low current.
(What is the voltage and current required?)
If so then the SSR power consumption problem mentioned by AK in post #11, should not be a problem.
Do you have an SSR selected?

KeepItSimpleStupid

Joined Mar 4, 2014
4,153
Can you grab the SSR power from the datalogger?

AnalogKid

Joined Aug 1, 2013
8,536
The little DIP packaged, 0.5 A, MOSFET output SSR's I've seen have 10 mA typ. LED current.

ak

crutschow

Joined Mar 14, 2008
25,256
Can you grab the SSR power from the datalogger?
Then you are not isolated and don't need the SSR.

crutschow

Joined Mar 14, 2008
25,256
The little DIP packaged, 0.5 A, MOSFET output SSR's I've seen have 10 mA typ. LED current.
But he may just need a high sensitivity opto isolator and not an SSR if all he has to do is trigger a low-current signal for the data logger.

Logzy

Joined Jun 4, 2019
6
Cant grab power from the logger.
The logger itself runs on 2x "D" size 19000mah batteries and gives up to 5 years depending on usage.
Data logger trigger is low current.

AnalogKid

Joined Aug 1, 2013
8,536
But he may just need a high sensitivity opto isolator and not an SSR if all he has to do is trigger a low-current signal for the data logger.
Yeah, I know. But up till now all we had was "MOSFET SS Relay".
Cant grab power from the logger.
The logger itself runs on 2x "D" size 19000mah batteries and gives up to 5 years depending on usage.
Data logger trigger is low current.
If both the timer and logger are battery powered, a simple open-drain FET might be enough.

Data logger trigger input spec / part number / link?

ak

Logzy

Joined Jun 4, 2019
6
Yeah, I know. But up till now all we had was "MOSFET SS Relay".

If both the timer and logger are battery powered, a simple open-drain FET might be enough.

Data logger trigger input spec / part number / link?

ak
Logger is a "Captis Pulse".
We would use "Switch 2" on the device which is the Red & Blue wire accoring to the limited specs hence my reason for a SS relay to close/switch this. I dont think we can provide a signal to one wire, easier jo just close the contact.