Scoop Scoop! **Tekka and I, are very glad to show you Aeos, our new great project. **


Aeos is a super tiny cube, built with the latest technologies for a low power and versatile device which can be derived in even more tiny devices in your home automation.

Don't hide it, it is so cute :)


On left : Aeos cube version. On right : Aeos 9in1 compact version!

Aeos project is made of :

• a main board with a lot of optional features, for more derived versions.
• optional extension boards
• and a very compact 3d printed enclosure. Aeos, cube version, is for example 36x36x36mm outer edge.

Let's see what's embedded..

Example of a wip assembly for the cube version

The main board

For helping in our decision, I designed some dev boards for testing different mcus etc.. and have drafted multiple iterations for this project. Because of time for maturation between these, each time I was looking again at it, there was always a little detail not ok or missing.. You can ask Tekka, I was close to be thirsty and hungry, with all these brainstormings and dilemmas!

Finally we ended up with an interesting proto..

Aeos protoype

Note : this is how looks the prototype, because the new revision has sensors onboard..

1) MCU choice : NRF52832 module

When possible, for RF, it makes sense to use an all integrated mcu, keeping cost down and easier for making smaller things.

Aeos is based on the recent Nordic NRF52832 mcu, a very powerful RF chip, compatible with NRF24! (footprint compatible with the cheaper NRF52810) Bye bye nrf24 clones :)

You can also note this prototype and first revision of the project, are using the Raytac nrf52 module, FCC certified. (meaning.. i have another mainboard, different, with custom antenna).

See the impressive NRF52 specs which appelead me:

• ARM Cortex M4F, 512KB flash, 64KB RAM
• Complete RF solution for BLE 5 and NRF24 compatible in Mysensors, so much possibilities !
• And wait, NFC compatible too!, only need an external antenna
• 128-bit AES HW encryption
• Serial Wire Debug (SWD) and can also be used with a bootloader for uploading with ftdi.
• Arduino compatible, with both SWD and ftdi-like interface
• 12 bit/200KSps ADC, 8 configurable channels with programmable gain
• 15 level low power comparator with wake-up from system OFF mode
• 3x 4-channel pulse width modulator (PWM) units with EasyDMA
• Digital microphone interface (PDM)
• 5x 32 bit timers with counter mode
• Up to 3x SPI Master/Slave with Easy DMA
• Up to 2x I2C compatible 2-wire master/slave
• I2S with EasyDMA for audio
• UART (CTS/RTS) with EasyDMA
• 3x real time counter (RTC)
• Operation voltage: 1.7V to 3.6V
• Peak current: 5.4 mA RX, 5.3 mA TX at 0 dBm.
• 0.4 uA OFF mode, 1.8 uA idle (i thought to use the sexy esp32 in first place, but it's a bit bulky and RF less power optimized for coincells)

I could highlight everything! so powerful and well suited for lowpower, coincell and RF.

* 2) Compact and versatile main board *


Here the new revision with an extension board. But like i said the new main board is enhanced with a set of sensors onboard, and one could also hook a reed switch for a pretty discrete and thin door contact sensor!

So, we have two options:

• assembling only mcu and basic circuit needed : for simple beacon or connecting a sensors extension board
• assembling the full board with sensors

• 2layers
• 33x33mm. Personal challenge :) to fit all of this, taking care of antenna clearance.
• Compatible with breadboards for prototyping.

• Battery holder footprint for coincells (CR2032, CR2450, CR2477). max voltage is 3.6v max without regulator need.
• Optional LDO regulator footprint
• Resistor divider (<1uA) for **monitoring battery** voltage in case batt > 3.3v
• Onboard 32.768Khz quartz for low power stuff and RTC
• Optional inductors for DCDC mode
• Micro right angle Reset button
• Optional RGB led
• More memory with an optional 4Mb SPI Flash for datalogging, otas etc.
• NFC pads for connecting an external antenna + tuning capacitors footprint
• Reverse polarity protection
• Onboard sensors footprints for a tiny and slim sensor node or beacon without extension : Temperature/Humidity/Pressure/Lux/Accelerometer/UV
• Possible to mount some cheap aliexpress i2c sensor boards

with a dirty cheap SI7021 clone board from aliexpress

• Pinheader for programming : SWD, FDTI in case of bootloader (onboard DTR management)
• Compatible with the excellent Fiddy, i’ll maybe do a few changes regarding my board but it's really a great idea, Kudo to his author! (https://www.thingiverse.com/thing:1908528)

I have also designed another revision, still the same with lot of sensors. But this time with a custom antenna, and a 4 layers pcb for better RF performance, regarding antenna and clearance, its gnd plane vs the routing and board size.. This revision is a bit different. It is 1.27mm pitch but brings more pins out. I'll use a very simple adapter to breadboard, not a big problem :) The coincell holder is changed too, i'll use the keyfob style with two options for the "Plus" pin. This is because i need more clearance for a better antenna than with the chip antenna from Raytac module previously.


*3) Extension board example for a gorgeous 9in1 *

This is a 9in1 extension board for monitoring and processing ambient parameters, actuating, or as an advanced security device for glass and door intrusion.

9in1 mounted to the mainboard

or on breadboard..

Of course, all sensors have been carefully chosen for their low power, voltage range and so on. Onboard footprints:

• PIR motion sensor compatible with big Fresnel lens: compatible with analog PIR like LHI968 by using low power comparator modes (the lowest power mode), or with the AM312 digital PIR, or new revision has a footprint for low power controller E931.96
• Lux sensor for ambient light measurement : OPT3001, cheap and great
• Precise UV light sensor : VEML6075 true UV sensor. Very nice for UVA/UVB/UV index/Power
• Temperature/Humidity/Pressure sensor : BME280 or SI7021
• Hall Effect for door contact sensor (door contact..) : DRV5032 or SL353LT etc. with same footprint
• Accelerometer : LIS3DH, cheap, for tilt (actuating, one tap, double tap, shake it ..) and vibration (door or glass shocks)
• Microphone, experimental, but could be used in combination with accelerometer for detecting a glass break pattern maybe, (or for actuating)

There will be a few more extension boards though.

Powering extensions :

• usb extension with optional battery charger and CP2104 usb interface, in case we would like to code and have fun without to remove the box

For more sensors and fun :

• air quality,
• rgb feedbacks,
• gesture
• radar sensor for motion..

* 4) The enclosure *

Better 3d printed, so we can get exactly what we want, and this removes some design constraints, because there were enough constraints!
The cost of printing is also very cheap, less than 0.5€ for a tailored enclosure like this. Another very nice point : choice of enclosure color ;)

Three types of enclosure actually :

• Smaller size : beacon style, the thinnest version

For thin CR2032 coincells, without extension board but 6in1!

• Intermediate size : ultra compact 9in1

For coincells, CR2032/2450/2477. So tiny with all these sensors!

• Cube size

For coincells, 14250 lithium batteries, usb. Gorgeous and so sexy :)

And soon a customized led shaded acrylic, laser engraved, front plate, yay!

Known issues

TODO

• Upload files, be patient please :)
• etc.

Contributors

Special thanks to

• Tekka from Mysensors Core Team, for feedbacks and motivating me
• @d00616 for his Mysensors NRF52 port
• Mysensors Core Team :)
• Nordic, Adafruit, Sparkfun, TI, etc.. for all educational infos they share

Links, reference and license

• Copyright Scalz (2017). released under the CERN Open Hardware Licence v1.2