Hello,
I'm working on a project where I want to transmit a signal from a small device that simply displays if two parts are connected. I was planning to do this with the basic circuit attached, where the transmitter will send a signal when the switch is closed. I want to keep this circuit as small as possible, ideally to be able to fit in the palm of a hand, and was wondering the best way to transmit a signal while keeping things small. It would be a benefit to be able to store limited data in the device and transmit over about 20 feet or less of distance. Bluetooth and RF both come to mind, but I haven't attempted anything like this and was looking for advice for components and builds. There are chips such as the bluno beetle (Beetle BLE - The Smallest Board Based on Arduino Uno with Bluetooth 4.0 - DFRobot) which can receive bluetooth data, but a small transmitter seems more difficult.
cattledog:
BLE beacons can be pretty small, and you may be able to switch power to a BLE beacon.
So the idea would just be to connect the beacon to the switch such that when the beacon receives power and is in range of a receiver it would send an on signal?
Something I'm seeing with a lot of beacons is that they have hardcoded functionality. ie: they only send temperature data. Are there any that are commonly used with arduino, or is there an easy way to just record the time that they are turned on/off? Such as transmitting between 10:45-11:15 or something like that?
How difficult would it be to just create an app instead of the arduino board? I have about 3 semesters of comp science experience but haven't done any app development.
cattledog:
Can you explain more about your project?
As you want to add more functionality, the beacon idea looks less likely. I was responding to your desire for "small".
Why do you think the bluno beetle ble is only RX and not TX?
There is also a beetle esp32 which looks pretty small.
Sure,
the concept is to record when two separate pieces are connected. I want to record the timestamps of when the connection starts and when the connection ends. Ideally I'd be able to store this info so that if a receiver is not in range the data can still be recorded and sent over to some sort of server when the receiver comes into range. The device also needs to be wireless so that it can be affixed to clothing.
In terms of size the smaller the better, but I'd say the upper limit would be maybe a cube of about 4x4x4 inches.
It does look like the beetle esp32 would work but the power supply only supports USB interface, so I'm not sure how I'd power it. I was mistaken thinking it could only receive, it looks like it's bidirectional.
the concept is to record when two separate pieces are connected. I want to record the timestamps of when the connection starts and when the connection ends. Ideally I'd be able to store this info so that if a receiver is not in range the data can still be recorded and sent over to some sort of server when the receiver comes into range.
Not appropriate for a beacon. This is sounding more like a wireless data logger.
Can you focus on the size requirement?
How much data do you think needs to be stored on the contact monitor?
Does the time stamp need to be related to real world time, or is it just an internal time value from the processor?
Do you need auto connect to a receiver, or can the receiver initiate the connection?
What will the receiver do with the information.
Specifically I want to make a cube to house the electronics. The cube would be constrained by the dimensions of whatever components get used. Ideally the cube would be no bigger than 2x2x2 inches and smaller is better.
cattledog:
How much data do you think needs to be stored on the contact monitor?
Just the on/off times for up to maybe a day or two. Only about ~20 time points and after offloading they could be cleared.
cattledog:
Does the time stamp need to be related to real world time, or is it just an internal time value from the processor?
Real world time.
cattledog:
Do you need auto connect to a receiver, or can the receiver initiate the connection?
What will the receiver do with the information.
When the two components that fit together connect I want to automatically send the connection to the receiver and log the time.
cattledog:
What will the receiver do with the information.
I just want to offload from the transmitter and store it for now, I might plan and use it later but for now just store it in a log.
If you google on ds3231 you will see images for a smaller one with a little yellow battery which is not easily replaced.
What are your thoughts about the receiver. Phone? Laptop?
Ok thank you I'll look into that.
For the receiver I think an arduino capable bluetooth board would work well for now. Long term I want to be able to automatically upload the time stamps from the board to a cloud file or something similar without having to use a computer but that isn't super important for now. Just being able to aggregate the data somewhere is most important now.
