I am working on a project to collect data from 10 to 20 RF devices. 802.15 is the ideal solution, but bluetooth has an advantage of being in almost every mobile device, phone and tablet.
Is bluetooth suitable for many to one cluster? Most apps i see are one to one.
onsdag den 12. maj 2021 kl. 01.10.36 UTC+2 skrev Ed Lee:
It's been 20 years since I worked on bluetooth, but I believe it is still limited to seven slaves and one master at a time
Then i have no choice but to go with 802.15.
it's all 802.15, Bluetooth is 802.15.1, Zigbee which I guessing you mean is 802.15.4
Yes, 802.15.4. By the way, do you know what they use in tire pressure monitoring TPMS?
315/433MHz (depends on market) It is VERY short-range. It may be something as trivial as modulating the carrier with the analog "pressure" signal (depends on vendor)
Note that it is a very low duty cycle system; it sleeps when the tire isn't moving (accelerometer). And, only broadcasts information every 30 seconds or so (depends on vendor) -- tire pressure doesn't change very quickly!
[A "decompression event" will trigger an asynchronous alert]
Can't you use broadcast?
You would need a synchronization scheme, so let one unit start, let's call it unit A Unit B will wait for Unit A to finish the broadcast. Unit B transmits, while Unit C takes over. Yada Yada.
The receiver listens to all broadcast messages
Never tried it, but may work
What if Unit B is down, then C wait forever? Also, all unit will need to have TX and RX. Some of the devices might be TX only.
I am thinking random time spacing broadcast, with checksum. Collisions are ignored, rather than providing wrong data.
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