Pir AS 312 with 2 rechargeable AAA battery. Boost needed?

[franz-unix]

@rvendrame Thanks, I have tried your small "nap" trick and in fact something is happened... but in the opposite direction! The number of false positive is increased :joy:

But probably this is the way to solve the issue. Please note that, in order to stabilize the battery voltage, in the sketch I already have a cr2032_wait() function that sleep the MCU after each radio transmission, if the battery type is set to CR2032.

[franz-unix]

Hi guys, project finished! Now the led are under the Fresnel lens, so the design of the case is more clean (WAF +10 :sunglasses: ).

The final result:

With 2 x AAA batteries and the RFM69 radio module the node works very well and the total cost of the parts is about 10€.

If someone is interested, here a detailed build guide, with the links to all the parts of the project (3d model of the case, Kicad project, gerber files, BOM, firmware).

[huex]

few month ago ,i use tlv61220 step-up boost only for as312 is only 4ua， atmega328p ,battery cr2477 , then get 21ua ,
but now ,i give up boost , i test use ER14335 3.6v CR16340LIPO 【4.2V with diode 0.7V Step-down then 3.5V+- 】 ，same as312 get 18ua,:relaxed: ,ER14335 cost much but 1600mah ！ cr16340 750mah rechargeable best choose for me,,,,

[DenisJ]

@franz-unix
This is wonderful work... thanks for inspiring me :-)
I know that this is an old thread,
but can you give me a link of the AAA battery holder please ?

I just make a node sensor and I want to use it.
Thanks a lot
Denis

[franz-unix]

@DenisJ : Glad to know that this work has been useful for you in some way. :+1:

Regarding the AAA battery holder, the footprints on the PCB are for a Keystone 5204 (negative) and Keystone 5226 (positive) contacts.

I have purchased them on ebay; unfortunately the item that I have purchased is not more available, but this one appears to me like the same thing.

[DenisJ]

Thanks a lot Franz... I have buy this one... maybe is more little

Thanks again
Denis

[franz-unix]

@DenisJ the link is broken, so I have not seen the contacts that you have bought, but if they are just a little bit smaller and they can fit the hole on the pcb, they should be OK.

[DenisJ]

I don't know... the link it's work on my side.
Anyway here is the pic:

Yes, I think will be ok... I hope :-)

Thanks a lot
Denis

[Diego Serrano]

@franz-unix Hi, this post is very old I hope I can get an answer :)
I have ME2188 here but the behaviour of CE pin in extrange.
If I apply high to CE pin I get my correct 5v but if I change CE pin to low I get 4v on the output and I hope to get 0v.

Anyone can share your experience?

[Nca78]

@Diego-Serrano said in Pir AS 312 with 2 rechargeable AAA battery. Boost needed?:

@franz-unix Hi, this post is very old I hope I can get an answer :)
I have ME2188 here but the behaviour of CE pin in extrange.
If I apply high to CE pin I get my correct 5v but if I change CE pin to low I get 4v on the output and I hope to get 0v.

Hello, this is the normal behavior for this chip. CE will enable the step up, but with CE low it acts as a bridge so you get input voltage at output.
Pretty annoying :)

Anyone can share your experience?

My experience was to add an MT9700 power switch before the voltage input of the ME2188. The EN pin of the power switch is connected to the same signal than the CE pin of the MT2188, driven by the microcontroller.
It works fine like this driving a Plantower PM sensor not a PIR (don't pay too much attention at the caps at output I just wanted to have different footprints available).

[Diego Serrano]

@Nca78 said in Pir AS 312 with 2 rechargeable AAA battery. Boost needed?:

Pretty annoying

Thanks you very much.

[ali kaka]

One Last (boring 😂 ) question... Have you placed a flyback diode across the inductor? I'm not sure if this component is strictly necessary.