I've done some testing with having 2 different HC-SR04, however I don't believe that this route will work, at least not with these specific modules. It seems that as soon as the module has received its echo, it stops listening for more echo's, which puts this part dead in its tracks.PiGraham wrote: ↑Tue Nov 05, 2019 4:38 pmIt sounds like you need battery power and small size.
Maybe Pi ZeroW plus a USB power pack but maybe ESP32 or ATTiny which could run on a coin cell for a lot longer than the Pi.
For sensing Bluetooth might be an easy option. You could read the RRSI signal strength of each Bluetooth or Wi-Fi device. Useful range maybe something like 4 to 15 metres for BT and 10 to 50metres for Wi-Fi? As you say that may not give reliable range.
You could set up dome fixed beacons and have each target device read RSSI to each of those and triangulate and average it own position. If every device can report a position relative to those fixed points you might get better ranging.
I don't know. Only speculating.
Another option could be ultrasonic chirps. There are lots of cheap transducers out there. HC-SR04 distance sensors.
If you made the targets listen for a ping from the seeker's device and instantly ping back. Then the time between the initial ping an the second / 'echo' relates to the distance to the target.
I say second echo because the seeker's SR04 will get a echo from it's own ping from nearby objects then a bit later it should hear the reply ping from the target.
You could use Wi-Fi or Bluetooth to tell targets to reply or remain silent so that the seeker devices isn't overwhelmed by lots of replies.
Maybe send a BT message to activate target 1 an silence all others, do the ping to get range to target one.
Repeat for each of your targets. Then sort the ranges to get the closest one and use that for your hot / cold signal.
You don't have to use HC-S04s. There are various transducers available and it may also be possible to modify HC-SR04 to change how they work.DaedalusOS wrote: ↑Tue Nov 05, 2019 7:08 pm
I've done some testing with having 2 different HC-SR04, however I don't believe that this route will work, at least not with these specific modules. It seems that as soon as the module has received its echo, it stops listening for more echo's, which puts this part dead in its tracks.
You could put multiple USB BT adaptors on a Pi, arranging antennas in a wide triangle or whatever.
Depends on the transmit power and receiver sensitivity.Do you know what sort of range can be achieved with low cost RFID
There are two guides here on how to make e.g. a RPi Zwro W into an iBeacon or an Eddystone beacon:DaedalusOS wrote: ↑Tue Nov 05, 2019 3:54 pmGreeting!
I have a Pi 4 4GB, and I've got an idea for a project, however unfortunately I'm really having a hard time figuring out just what to properly use to accomplish my goal.
What I want to do is basically setup a scavenger hunt using my Pi. I want to have small little devices (or anything at this point) that I can hide around the area, and the Pi can sense the current distance from itself to that object. The actual area that these little things will be hidden in is my apartment, so really not that big of a search grid. In a perfect world, I would want whatever devices to be able to be detected by the Pi from a handful of feet away so that I can throw in a buzzer or an RGB light that would go from blue to orange (cold to hot) the closer you get to the device.
I thought maybe what I could do is setup some Pi Zero's and connect them to my main Pi with bluetooth and then use RSSI to see if I can get the distance, however I'm not entirely sure that will be reliable enough.
Does anyone have any ideas here? Just looking for some advice.
Thanks, and I really appreciate it!
Yes, RSSI is read and reported per default by most BT apps, but I don't know what the tx power byte does in relation to that.
RFID is not the way. You can get RSSI on the readings in the same way as for Bluetooth, but it requires expensive equipment in both reader and antenna. But the RSSI is not any better than with Bluetooth, and you have cheap beacons and cheap readers for Bluetooth.DaedalusOS wrote: ↑Thu Nov 07, 2019 7:50 pmAlright, after reading all of your responses I feel my exact goal may be a little more complex than what I wish to put into this right now, so I'm going to think about alternative methods to achieve something similar.
How about RFID? My only issue here is that after looking some of this up, I'm worried about the range. I would like to be able to detect if I'm within range of an RFID chip by maybe a couple feet, and preferably a passive one at that. Any ideas? Is there any way to detect range as well, or no?
Yep not the best finding solution.I tried a couple but they don't seem effective. The reported signal strength doesn't vary with distance in a consistent way.
That's exciting tech. Sub 1m accuracy with direction and elevation.
Passive RFID detection range depends on the size and quality of the RFID tag and the chosen antenna.DaedalusOS wrote: ↑Fri Nov 08, 2019 2:13 pmI think I'm gonna go ahead and order a Pi Zero and see what I can do, and take a look at all of your suggestions.
In the event that I do choose to go with RFID, which type should I go with? I'd like it to be able to be detected from maybe a couple feet away, or maybe even just a foot away.
Thanks everyone for your input, I greatly appreciate it!
Those are probably NFC tags or short range ID cards and access tags.PiGraham wrote: ↑Sun Nov 10, 2019 9:08 pmThe cheap maker kit I've seen is a range of a few centimetres (~2cm)
Can you give examples of kit that works at more than 10cm?
Nothing specific that might suit this application?
The latter RFID reader is handy, and acts as a USB HID keyboard device, so it should be easy to interface with it, as the ID of the RFID tag read is being sent as keyboard key presses.PiGraham wrote: ↑Mon Nov 11, 2019 8:08 amNothing specific that might suit this application?
There are things like this:
https://www.amazon.co.uk/reader-vehicle ... B018EFLJJI
which claim 3 to 5 metres reading range but would that give useful proximity range info under 3m?
It large for handheld use (20cm) and it's £150.
Then there is this one:
https://www.amazon.co.uk/dp/B075WY8DSR/ ... NrPXRydWU=
Similar price, range 10 to 150 cm which may be more appropriate 120 x 85 x 23 mm