Telemetry platform (for home, HA) ? - Page 1
Forum section: electronics / rf-microwave

author: onesixright
author_rank: Frequent Contributor
timestamp: July 06, 2018, 09:28:54 am
content: Hi All,I'm in the early steps of designing some platform for ~ 70-100 sensors that needs to be wireless connected. Each board will have 1-3 sensors (SPI / I2C), 90% indoor (sensor), 10% outdoor (sensors). Of which afewneed long range (100-1000 meters). Most sensors will be sending the data based on a simple interval (will be in the minute range 1-5). A few others will be IRQ driven.The data will be collected by a RPI (not truly important since this can easily upscaled if needed).I was thinking to designing a simple platform consisting of a MCU, a RF transceiver and power supply. I for sure don't want to use something like Arduino's, that seems to be overkill.At this point im leaning towards a PIC16 + (MRF89XAT-I/MQ or RN2483-I/RM095). The latter one being a LORA transceiver.I have a few concerns.1. Probably there is already a existing platform / MCU that contains these basics (MCU + RF)?2. How to deal with collisions: push vs pulla. let the RPI be a master and read (pull) the data out of each sensor).b. just have every sensor send it data on out on intervals (collisions /malformed packages?)3. Mesh network support: zigbee, miwi (microchip) any other (would solve 2b?) ?4. What would be a smart way to deal with the batteries. 30-50 boards, with batteries sounds like a "nightmare".Any other advice much appreciated!Thanks.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 06, 2018, 09:34:48 am
content: Quotethe problem is which freq do you want use for?433?, 868? If you want use one of them please keep in mind the duty circle (who is 10% when I remember right).Or 2,4Ghz?

author: onesixright
author_rank: Frequent Contributor
timestamp: July 06, 2018, 09:43:03 am
content: Quote from: Lord of nothing on July 06, 2018, 09:34:48 amFor long range I was planning to go with a LORA TRANSCEIVER (868 Mhz). Its very little data.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 06, 2018, 09:48:34 am
content: 500m - 1km outdoor?When I remember right you can use 500mW Power and you need to use an Duty Circle.Is that for an Industrial Application or for different customer?

author: onesixright
author_rank: Frequent Contributor
timestamp: July 06, 2018, 09:56:37 am
content: Quote from: Lord of nothing on July 06, 2018, 09:48:34 amIts just for myself.My mailbox is 1000 meters away (as the crow flies, slightly downhill ~ 75 meters). I wanna put a accelerometer in and send a signal if it gets opened (mailman)

author: nfmax
author_rank: Super Contributor
timestamp: July 06, 2018, 11:14:18 am
content: To me that sounds like a job for some JeeNodes:https://www.digitalsmarties.net/products/jeenode, which are Arduino-compatible Atmel microcontroller boards with an 868MHz radio. Designed (in the Netherlands!) for just such a job. I've never used them myself, but hear good things about them.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 06, 2018, 11:52:25 am
content: Quote from: onesixright on July 06, 2018, 09:56:37 amPut some Pi there and use an Fiberglas Cable for Isolation.

author: iak
author_rank: Newbie
timestamp: July 07, 2018, 10:15:45 am
content: Accelerometer, I think it might be not efficient, and you would need some data processing to get the data to really represent something.Probably a magnetic switch would do a better job here !

author: onesixright
author_rank: Frequent Contributor
timestamp: July 07, 2018, 10:35:12 am
content: Quote from: iak on July 07, 2018, 10:15:45 amThanks, good point.For those curious, its a Czech mailbox.The thing is, its not "my" mailbox, its property of the post. So I don't want to drill stuff etc. There are basically 4 mailboxes next to each other (see pic). And when they insert the post the whole front opens downwards (over the horizontal axes). Well thats what they told me, since there are no numbers on it. Only the mail(wo)men can see which one is which (house)number (once opened).I would expect that I can simple trigger on that motion (magnetically (eeks)). Problem is that although it can easily rendersome false postives(i.e. mailbox opened but mail is not for me). Nevertheless, much better then going up and down daily for nothing. Not even sure if the range, and the fact its inside a metalbox would give me a goodrangesignal.Thinking of it, a bit of exercise wouldn't hurtMaybe I should "bride" the post, ask them if they can bring it in exchange for some coffee, most of its now-a-days is digital.