Device recommendation

embedded
1

Hi everyone :slight_smile:
I have a small project in mind and am currently searching for a good device recommendation I can use.

In short: I want a set of nodes that periodically transmit sensor (3-5 sensors) data to a main device.

Requirements:

  • Should be low power (the less, the better)
  • at least one analog input
  • if not enough analog inputs, some digital outputs in order to control a multiplexer (so 2-3 digital outputs)
  • ideally runs of some common battery voltage (3.3V, 5V)
  • ability to send data (no receiving required), at least 20m range, with stone/brick wall
  • programmable with rustc
  • clock to wake device up from sleep
  • working temperature should contain 15-45°C

Pros:

  • Integrated radio/Bluetooth-le
  • no unnecessary hardware (I found some mc's with integrated radio where the CPU capabilities of the radio chip would have been more than enough for all my sensor nodes :upside_down_face:)
  • aes support

Not important:

  • hal support (I wrote a micro kernel for a armv4 board without hal once, so I'm confident on that front)
  • memory management/protection unit
  • float support

My biggest struggle is currently finding a mc that is not bloated with hw features, and promises a long battery life.
My hope would be to measure battery life in measurements taken so the device should have a "basically off except the clock" mode.
Regarding the radio: this is something I have absolutely no experience with and would be happy to take any hints/recommendations what to look out for (how does for example a simple radio transmitter compare to ble?).

Thanks in advance :smiley:

2

Sounds like Nordic's nRF52 series might be a good fit. They have 2.4 GHz radios that do BLE, ZigBee, and a couple of other protocols, as well as a built-in AES engine (some have an Arm CryptoCell too).

3

Thank you for the recommendation, that SoC really looks like a good fit.
Just two more questions regarding my understanding of the documentation of the nrf52805:

  • it is not possible to awake from the OFF state using the clock source LFXO
  • LXFO requires external components

Do you happen to know if I understood these points correctly?

4

No, I haven't really done any hardware design or low-power things with the chips so far

5

Follow up:
I ended up ordering a bunch of bc805m which package a nrf52805 product page
Additionally I ordered a nrf25840 for ease of development (different soc, which supports mostly a superset of the nrf52805) and a j-link for programming and debugging the bc805m's.

If all works out as I think this should be all I need to get started :slight_smile: