Need recommendations for smallest available components for prototype 2.0

Using Arduino Project Guidance
#1

Hi. We are new to Arduino and microcontrollers over this last month. We made a simple prototype which has a button which, when pressed, sends a timestamp to our Android App via bluetooth.

For our prototype 1.0, we used the following (which we were able to buy here in Thailand):

Arduino Bluno Beetle BLE
1307 RTC
2x2032 batteries
Button

Attached is a photo of the the guts of our first prototype. Note that since this photo, we switched to soft servo wire. This allowed us to fold our components into the smallest possible volume, and make the smallest possible housing for it.

Our goal is to go smaller, as small as possible with over the counter parts. Can anyone recommend the best combo of the above required parts to make the smallest possible package? I can order from USA and have shipped to me here.

Also, the RTC we used has its own battery. I assume the battery allows uninterrupted storage of the timestamp. Does that battery also power I/O for the RTC? My team ran power from our dual 2032s to the clock chip, but I’m wondering if that was necessary.

Thanks for your help.

asthma-sensor-prototype-soldered-small.jpg
asthma-sensor-prototype-soldered-small.jpg1000×680 134 KB

#2

Hi,
Why do you want it as small as possible?

Tom.. :slight_smile:

#3

It is a device that will go on another existing device and we want the smallest profile possible. It will fit like a cap. More than that I can't say :slight_smile:

#4

macnmotion:
... More than that I can't say :slight_smile:

What goes around, comes around.

#5

ChrisTenone:
What goes around, comes around.

Huh? Maybe I don't understand, is there something wrong if I don't disclose the ultimate purpose of the device?

#6

https://www.digikey.com/en/product-highlight/r/rf-digital/simblee-bluetooth-smart-module

The first is a very tiny btle module that can be programmed directly with Arduino code.
The second is a more tranditional Arduino Micro style board with an external, btle module.

#7

Do you really need the RTC? Can't you simply get the time of the keypress on the receiving end (your Android app should know what time it is)?

#8

macnmotion:
is there something wrong if I don't disclose the ultimate purpose of the device?

This is an Open Source Forum.

if you are unwilling to tell us about your project my first assumption would be that you are looking for free advice for a commercial project - and I don't like that.

...R

#9

you are asking for smaller, then get a smaller RTC.
if you eliminate the RTC battery it will reset to some starting point on battery loss.
if you can live with that, then bob's your uncle on 2 batteries.

since you require commercial products, look at the buttons on toy displays.
they have a tact switch and one battery, you can find out who make them with 2 batteries and you are killing two birds with one 14 pound weight.

#10

Robin2:
This is an Open Source Forum.

if you are unwilling to tell us about your project my first assumption would be that you are looking for free advice for a commercial project - and I don't like that.

...R

Plus 1

#11

larsgregersen:
Do you really need the RTC? Can't you simply get the time of the keypress on the receiving end (your Android app should know what time it is)?

We can't because there may be keypresses when the phone is not in range, and we need to track times of those presses as well.

#12

Smallest: make your own PCB with just the required components.

You do not need an RTC to keep accurate time with an Arduino, just an accurate crystal for the CPU clock.

#13

jremington:
Smallest: make your own PCB with just the required components.

You do not need an RTC to keep accurate time with an Arduino, just an accurate crystal for the CPU clock.

Yes, absolutely later we would have a custom PCB. The project is still in proof of concept stage so I'm hoping to make the smallest prototype as possible myself at this stage. I didn't realize an RTC wasn't necessary with an Arduino, thank you for that information.

#14

Robin2:
This is an Open Source Forum.

if you are unwilling to tell us about your project my first assumption would be that you are looking for free advice for a commercial project - and I don't like that.

...R

Ahh, OK I understand your point. I had read the "how to use the forum" and didn't see anything about whether your project had to be revealed. I wouldn't expect anyone uncomfortable with giving advice to do so.

In any case, I have revealed what the Arduino device is. It's merely a device that records the timestamp of a button press and sends it by bluetooth to a phone, and it needs to be as small as possible at this stage (later I would have a custom PCB). Whether it sits atop another device, or what is happening in the app after the timestap is sent, really has no impact on the Arduino component of the project. I am not in any commercial phase of anything, I have an idea I want to explore and I thought that Arduino technology would be good for my testing. If I'm the only person here who has asked for help when using Arduino technology to explore a possible future business idea, that would probably surprise me. But I do hear you, and appreciate your comment.

#15

westfw:
https://www.digikey.com/en/product-highlight/r/rf-digital/simblee-bluetooth-smart-module
Adafruit Feather 32u4 Bluefruit LE : ID 2829 : $29.95 : Adafruit Industries, Unique & fun DIY electronics and kits

The first is a very tiny btle module that can be programmed directly with Arduino code.
The second is a more tranditional Arduino Micro style board with an external, btle module.

Thanks for this great information.

#16

macnmotion:
Yes, absolutely later we would have a custom PCB. The project is still in proof of concept stage so I'm hoping to make the smallest prototype as possible myself at this stage.

so, when you stated as one of the few requirements :

Our goal is to go smaller, as small as possible with over the counter parts.

you were not honest ?
if you are "ABSOLUTLY" going to make your own PCB then why waste our time trying to find smaller parts for you ?

#17

dave-in-nj:
so, when you stated as one of the few requirements : you were not honest ?
if you are "ABSOLUTLY" going to make your own PCB then why waste our time trying to find smaller parts for you ?

What on earth is wrong with you? Not honest? You're ridiculous.

I want to make the smallest version of our project with over the counter parts. This is called a proof of concept. Google it. If it works, and we determine to move forward with a real product sometime in the future, I would use a custom PCB -- as would anyone moving from prototype to production. I've been perfectly clear, but for whatever reason you've decided not to read and comprehend my messages. I certainly can't help that. But to call me a liar because you .... geez this isn't worth the time with you. Whatever issues you have, calling a stranger a liar on a message board isn't accurate, productive or becoming.

For those who have understood my question and provided me feedback I very much appreciate it, it has been helpful. Navigating the world of Arduino project components in a country where we have very limited choices has been difficult, and I came here to broaden my knowledge.

#18

Whenever one is secretive, while trying to glean knowledge, there is a perception of dishonesty. I'm not saying you are dishonest, but that how you come across by refusing to discus your project. Developmental secrecy is fine, but you appear to be wanting something from us without giving anything back in the process. Good luck with your project.

#19

macnmotion:
What on earth is wrong with you? Not honest? You're ridiculous.

I want to make the smallest version of our project with over the counter parts. This is called a proof of concept. Google it. If it works, and we determine to move forward with a real product sometime in the future, I would use a custom PCB -- as would anyone moving from prototype to production. I've been perfectly clear, but for whatever reason you've decided not to read and comprehend my messages. I certainly can't help that. But to call me a liar because you .... geez this isn't worth the time with you. Whatever issues you have, calling a stranger a liar on a message board isn't accurate, productive or becoming.

For those who have understood my question and provided me feedback I very much appreciate it, it has been helpful. Navigating the world of Arduino project components in a country where we have very limited choices has been difficult, and I came here to broaden my knowledge.

hon·est ˈänəst/
adjective

free of deceit and untruthfulness; sincere.
"I haven't been totally honest with you"
synonyms: truthful, sincere, candid, frank, open, forthright, ingenuous, straight;

derivation : “Honesty” derives from the Old French (h)oneste, which in turn derives from the Latin honestas. The Latin noun was formed from the adjective honestus, likely deriving from honos, “honor,”

I work with instructions from a client.
"I want a red box."
"well, I REALLY wanted a blue box, but......."

#1) we are not paid, and I am sure that you are not going to make millions of dollars and millions of units, then send each of us one for helping you on your project.
#2) you list very specific requirements, targets to meet. then say that they were not important because you are going to ignore them and do something else.

any help we have offered in that effort to meet your specifications is wasted time and effort because your requirements, your post was not truthful, sincere, frank, open, forthright....
now, go back and read what honest means again. then go back and look at your posts.

re-read the first post and your response. There was no ambiguity.

#20

jremington:
Smallest: make your own PCB with just the required components.

You do not need an RTC to keep accurate time with an Arduino, just an accurate crystal for the CPU clock.

Depends if you want it to use sleep mode - no crystal oscillator running then, RTC is the correct
option for micropower operation.