Is the Pico2 compatible with LoRa SX1262?
Looking through the Meshtastic course it mentions only using a "standard " Pico board or Pico W with separation
Also does flashing Meshtastic onto the Pico remove any previously loaded modules?
My project is to wirelessly transmit a tipping bucket raingauge momentary magnetic switch using Pico-loRaSX1262 to another Pico-LoRASX1262 to function a relay. Presently Im using an Elsemo 27MHz radio switcher and although the setup works the range through walls is not satisfactory
In the Meshtastic course Jared mentions using a pair of Pico boards to achieve something like activating a relay remotely from a swich.
I will leave the pico compatibility to the pico people.
What is the distance between the two end points?
Why do you think the 27 Mhz is not working well enough?
As a rule of thumb 27 Mhz will go threw walls/windows etc much better then 900 Mhz. So need to make sure that lora will work better in your environment.
Lora was designed to try to pull out more of the data from the weaker signal, so its a good start. I made some little lora point to point units to play, learn and test. So far with line of site, i.e. nothing to block the signal, I have had it working over about 4 Km (so wanting to find a longer line of site to see how far I can push it). But with the same gear, I was luck to get 50M when there was a house in the way. So you may need to run some tests to see what works. e.g. Higher gain antenna, best radio positioning, more then 2 nodes (as Mestastic can have repeater nodes).
You also need to consider what happens if the message did not always get threw. while Im sure it will do its best, there will be limits;
The Pico 2 currently is not officially supported by Meshtastic. We haven’t even tried flashing it with the Pico 1 firmware, and I’m unsure if I would trust it to be fully functional. For now, I would recommend using the original Pico for the Meshtastic side of it.
However, we use a 2nd Pico to handle UART messages and work alongside it as a pair. This 2nd Pico can be a Pico 2 and in a lot of the videos in that guide, we actually use a Pico 2 in the demos! Also remember that if you use a Pico 2 W or Pico W as your 2nd Pico, you can connect it to MQTT via Wi-Fi and connect it to the internet like we do later in the series.
I’m a bit hazy about your question about removing previously loaded modules, but when you flash the Meshtastic firmware, it will wipe clean any data stored on the Pico.
@Michael99645 is also right with 27 Mhz being able to get through walls and windows better than the Meshtastic frequency. I’m pretty sure that the LoRa module transmits at the highest possible power that you can do without a license in Australia though, but I couldn’t find any specs on the 27 Mhz radio you are using for comparison. Like Michael said, a 3rd well-placed node acting solely as a repeater would also be possible here (and you wouldn’t need a 2nd Pico for that).
Ive ordered a couple of Standard Pico H along with the stack headers to allow space for that pesky Molex on the underside of the SX1262. I should have looked more carefully at the full tutorial and ordered everything required from the get go
Anyway glad the Pico 2 boards will be used in tandem with the standard Picos running the LoRa
The Elsema GL 270412 is basically a 27Mhz 4 channel radio relay switcher, and works at a testing range of 15 metres but fails at the required range of about 30m even with an external matched antenna
I also tested a LoRa 433Mhz wireless transceiver switch PUFINS KHK-U-01 and although it communicated at the 30m range, and beyond, it was too slow to reliably detect the momentary switch transition from the raingauge
Hi Robert
I am not buying into this discussion but a couple of RF type statements stand out.
I don’t quite understand this. 27MHz is basically “citizens band” and works pretty well around all sorts of obstacles. Like most trucks have 27MHz transceiversNd don’t seem to have much trouble talking to each other sometimes over quite long distances. I have personally used hand held units in pretty adverse conditions with little trouble. Only for voice though.
I can assure you the 433MHz is more “line of sight” than 27MHz and I just don’t see how it seemed to have better signal strength than 27MHz. I think there may be other factors at play here. It would be handy to get some comparative RF signal strength measurements for a start but I don’t know what you have or how you are going do that.
Just thought I would drop this in to give you some more to think about.
Cheers Bob
Bob, while what you say is 100% my experience and what I have learnt, the key here is the missing information.
Power Level v spread spectrum. Most 27 Mhz CB Radios were 4 watts on AM and 12 watts on SSB, so a fair bit of push behind it. I suspect the power levels of the point to point unit is much less, hence not working as well as the OP would like. I have seen some radios use very low levels of power so that the mostly work over a very short distance, but wont fry the finals with poor antennas. e.g. a 1/4 wave for 27 Mhz would be about 2.5 M long (less with coils).
Spread spectrum as used in wifi 2.4Ghz, 5Ghz and now 5Ghz is really good at getting the data out of what we used to thing of as noise.
So I can see how a spread spectrum would work better then AM if power levels were too low.
The bit the concerns me here is I would expect 433mhz lora to work better then 915Mhz lora; i.e. same radio protocol, so the lower frequency should go further then the higher frequency radio.
I think this may need a little more thought. You may be right, but from the information provided so far, im not sure why meshtastic lora @915Mhz would work better then 433 Mhz lora. Lora is kinda slow and is a short messaging service; but the way the protocol works is there are delays.
e.g. (not actual values as I would need to look them up).
The transmitting radio is trigger to send a message (e.g. from your controller), so it creates the message and sends.
At this point it can only confirm the message got to the other end by a response to confirm it. There are 3 modes that a lora radio can receive.
In a time slot based on x ms from transmit. Normally there is a short one < 1 second and a longer wait > 1 second. while you think, easy lets make it a really fast response, you need to keep in mind that the remote unit must get the data, decode, process and then send the reply. If you have repeater nodes, you need to allow for them to get the packet and forward it.
Repeating fixed time slots. so in short the transmitter would need to wait for the next time slot to send the message.
Always on. So as long as the receiving unit is not transmitting it should hear the packet.
the pros/cons normally come down to power consumption, but each node should work the same way.
Can you explain what your packet flow and timings are needed.
e.g.
trigger is fired, packet sent to remote units < X amount of time.
Do you need a confirmation or are lost packets ok ?
Not necessarily. If you calculate the free space attenuation the 433MHz would probably be about 6db better (half the frequency) but this is usually offset by antenna gain with more gain being easier at the higher frequency (physical size). Also 900MHz probably bounces around a lot better with an iffy path. This is the frequency range used in Tropposcatter systems like scattering over the horizon or other obstruction.
But as you say the system used has probably a lot to do with results. But 15 or 30 metres is not very far. As the saying goes a wet bit of string should work.
Many years ago I was heavily involved in such a system where reliable comms were achieved at about 200km over water with a nominal TX power of 10W.
BUT (and this is a big BUT) a system of space and frequency diversity was used with antennas (2 at each end) of parabolic dishes, each one being 7m wide and 6m high and a gain of a bit over 30db. Not something to attempt at hobby level.
Cheers Bob
Thanks for the feed back,
My 27Mhz wireless relay switcher is very low power. It is virtually a garage door opener switcher. I have also seen them used to operate agitator functions on a cement truck. It has a very short range and although in principle the lower the frequency the better penetration, in my application, it does not work
My 433Mhz device I tested to over 1 Km line of sight sensing a simple switch via an onboard IO. However the switching detector will not reliably register a short change of state of the magnetic reed switch of my raingauge. Perhaps there is a delay engineered to defeat “noisy” switching. So it is not suitable for transmitting rapid switching events. It will be useful for other projects such as controlling a pump operated by a float switch 300m apart
Thats why Im going to give the Pico LoRA SX1262 a go. I know the frontend pico (2) can count the reed switches reliably. Hopefully the 915 MHz Pico /SX1262 will be able to transmit the data from my raingauge in my backyard to my house to be logged to file
Hopefully this sheds a bit more light on the topic
