Seeking Advice on Compact Object Tracker Components and PCB Design

Hi all,
I'm currently working on a small tracking project and could use some guidance on selecting the right components, since i dont have much experience and i don't know what to look for. The main goal is to create a compact tracker that monitors an object's movement, specifically detecting when it's picked up or laid down.

Here are the core components I'm considering:

Microcontroller: I need a microcontroller to handle the logic for data processing.
Gyroscope & Accelerometer: Sensors to measure rotation and acceleration.
Proximity Sensor: A proximity sensor with a range of a few centimeters is required to detect when an object is close to a surface.
Bluetooth Low Energy (BLE) Module: This is necessary for transmitting the tracked data to another device.

I'm would like for a final PCB size of max 5cm x 5cm; please let me know if this is a reasonable target.

Currently, I'm using an ESP32 with the MPU-6050 as the gyroscope and APDS9960 for distance measurement, but these components are too large (and have too much functions i dont need) for my intended design.

Any advice or component recommendations would be nice. Thanks!

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misaz over 1 year ago

These components should fit 5x5cm. Could you show your design which do not fit?
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shabaz over 1 year ago

There are many ready-made "BLE evaluation" boards with either all, or most of these parts on-board (and a connector for attaching your own board for custom sensors. They are about 2.5 x 2.5 cm.

Here's an example (others might be cheaper).

https://uk.farnell.com/on-semiconductor/rsl10-sense-gevk/ultra-low-power-sensor-no/dp/3019008?st=rsl10

Silabs had a 'sensor puck' that I think had everything you ask for too, and it was cheaper, but I think it's obsolete now. But circuit diagrams and source code are all available.
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m9roval over 1 year ago in reply to misaz

The ESP im using is already slightly over 5cm in width. I would rather go as small as possible and cut out all the functions i dont need due to the possibility of adding more sensors. Thanks for the response!
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m9roval over 1 year ago in reply to shabaz

i would like to create a few, so thats definitely on the expensive side : ) would you possibly know what cheap components i could get that are cheap? especially the BLE module and microcontroller; i wouldnt know what to look for. Thanks for the response!
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dougw over 1 year ago

You won't find a BLE MCU much cheaper or smaller than an ESP32 for ~$2.50
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ralphjy over 1 year ago

If you only need BLE, you might look at the Seeed-XIAO-BLE-Sense-nRF52840. It has an onboard IMU and microphone and is 21 x 17.5mm. You would have to add a proximity sensor, but there is a Grove-Time-of-Flight-Distance-Sensor-VL53L0X about the same size 20 x 20mm. You could remove the Grove connector and wire it directly to make the assembly more compact.
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shabaz over 1 year ago in reply to m9roval

I'm not sure what you're trying to optimise? Virtually every BLE microcontroller will easily fit within 5x5, even the ESP32 which you've already discounted. The ESP32-WROOM-32 dimensions are just 26 x 18 mm. You're unlikely to find much cheaper than an ESP32.
Any other option will likely be smaller, but may be more expensive.

Besides, if you just need a few, then just buying a ready-made board with sensors on it may still work out cheaper than custom designing your own board. Unless you're making dozens or hundreds.

In any case, if you want to make your own, then clearly the ESP32 fits your size requirement (with plenty of space spare for the sensors you mention. And is cheap.

What BLE microcontrollers have you already ruled out? You should have found dozens of BLE microcontrollers that meet your size requirement, so it will be interesting to know what was unsuitable about them.
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dougw over 1 year ago in reply to m9roval

The ESP32 below is much smaller than 5cm:
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