Some members of the community have guided me through the decision tree for buying my first wemo D1 mini boards.
I am now wondering what is the best way to power them. I have to install LOTs of these little bastards in my house and garden, and I have not the intention to start running the remaining of my miserable life to replace batteries ;-). Unless somebody has a good battery based solution of course...
If I need to install power wires to a large series of such devices, I assume one ore more central power supplies is the best way to go? Would be nice to get some advises and tips for things I should take into account. Because at longer distances (e.g. in my garden) I assume there will be voltage drops, I need to secure the power supply if I accidentally create a short wire, and so on ...
I have no experience at all with this, so all real life experiences and advises are welcome!
Just a simple mains to 5V adapter works fine - like the ones for older mobile phones.
This is what I purchase here in the UK.
If the location where you are going to use the Wemos D1 Mini hasn't got any mains outlets, then you'll need a battery-pack of some sort or another. Then you are going to have problems as the Wemos takes quite a bit of energy when it transmits via WiFi.
You can put the Wemos into DeepSleep, which is what I do with my weather stations, to conserve energy.
You then hit the question of how often do you want to take a pressure reading as that determines the sleep time and how long the battery will last before it needs charging.
I use either old phone chargers. Everything from 500ma up is fine. Simple easy and the unused power bricks get a usefull second life
Or I use one of these modules: Available from many suppliers. I use them for the more permanent installations.
If battery powered you might use one board with build in charging circuit and connect a LiPo battery to it. The wemos battery shield is known to be not the best design. But there are many others out there. Andreas "The Guy with the Swiss accent" did regular tests and good comparisons.
I think Bart is asking for anyone with experience of running long powered connections that might have significant voltage drops that cause the D1 to intermittently fail.
I've only ever done a 5M run and I used 20Amp rated mains cable from an old IPhone USB charger and didn't experience any problems - until the Wemos got wet and failed
Ok … then I use my 24v LED supply with step down switching modules for the esp. I do this with my garden spot lights. The ESPs are controlling constant current modules with pwm dimmer input. Voltage regulators aren’t the best choice as the dissipate the excess energy in heat.
5V over long distances pulling peaks up to 2W is not a good idea. (And the short apple cables are ridiculous)
Unless somebody has a good battery based solution of course...
ESP-Now can be battery efficient. You will need 1 ESP device acting as a gateway and the sensors will then only send messages to the gateway - even over long distances (500m+), some inspiration.
Expensive? Not at all. The garden spotlights run all from one 24v supply as the lower current isn’t that big issue and instead of having transformers or two per device) all over the place I opted for this solution. Having high power PWM over long wireless could get you into trouble with electro magnetic emissions. The spotlights are 9€ ones from china where I ripped out the drivers and replaced them with pwm dimmable ones.
Fixed installations I use these small switching regulator blocks.
And another in some cases the old chargers do thr business.
Your approach seams more difficult / epensive
Having a poe switch. Or power injectors
Expensive cabling
More expensive modules
And you might need power for lighting projects
In rather would spent a little bit more on decent Wifi APs (I use 3 UniFi light APs: one for each floor and one in the garden. 2.4 and 5GHz perfect handover between APs = no device stick on a bad connection when a better AP is nearby. One config utility for all APs at once not having a webserver in every device web or app. 80€ per piece and the family is as happy as my IoT devices = money well spend.)
So my philosophy is
off the shelf products as long as they are reasonable priced and not cloud based or able to phone home
hacked firmware on of the shelf devices (that is why my own firmware run on 1MB flash with OTA update possible)
DIY for all others. Then I use ESP32 or 8266 as needed
I live in a 19th century house so running cables is either not possible or painful and expensive
For power supply instead of one option decide what works well for each situation.
PoE for my APs is great as they need Gigabit Ethernet anyway
For thermostats or window sensors batterys a best. Even my zigbee 10€ motion sensors (Ikea) run from coin cells.
The LOLIN D1 Mini Pro V2.0.0 looks really interesting I'll have to buy some. Do you know if, like the Mini D1 Pro, you have to mess around moving a zero ohm SMD resistor if you want to use the ext antenna socket?
I have one but never used - no usecase. And I don’t see an antenna connector.
In my experience the pcb antennas on the esp modules are best (perhaps because pcbs can be produced with high accuracy and no connectors or cables needed). The ceramic antennas are crab and with external antennas I never got a benefit. Useful only in devices with metal cases or bad internal emf shielding or perhaps in my switchboard with a ton of cooper wires - but nope the pcb antenna is fine.
You can watch a ton of YouTube videos with esp range test for comparison.
No no I wrote 'extensive' . I meant you have a sensors I can only dream about at the moment.
If you have a link to that 5v board somewhere, please share it....
Did you get better link quality out of external antennas? I never got better quality then the pcb antennas on a wemos d2 mini. = esp12 module. But perhaps my antennas all where bad. But you will have to solder a jumper to switch a antennas (0 ohm resistor) (you know, high frequency electronics is the black art of electronics)
Well it should be better with an external antenna as the length of the physical antenna probably matches the wavelength better. Well, better than the gold printed track on the PCB.
I tried de-soldering the ultra-small zero ohm SMD resistor on three ESP32-CAM boards I have. Each time I managed to lose the resistor as it got suck to the tip of my soldering iron. With two of the ESP32-CAMs I had to rip-open the metal can and find a good place to solder the ends of the coax cable for the antenna!!!
It would be nice if they had a jumper arrangement on the PCB to select on-board or ext antenna - however I'm sure that would mess-up the UHF electronics (with three pins sticking up in the air).
You don't need to do that, just remove the 0k resistor and put a dab of solder to the other connector (red in the image) after all a 0k resistor and a blob of solder are the same thing.
A jumper will (perhaps) compromise the signal integrity of the signal path which is crucial in the high frequency range.
Here is some first hand information
In my experience the range of the ESP12F module (on the wemos board) is better than the external antenna i used together with an ESP07 (with correct jumper setting). The pcb antennas on some TTGO boards (not using the ESP12) was good but not as good as the ESP12 module.
Reading the document the problem seams is not the size in general it may be more the design and the placement. I place the antenna on the far corner of my designs outside the mother board pcb and avoid cables all over the place. The pcb antenna might be good but if you place shielding all around and ontop of a pcb with ground planes and what not no wonder that you don't get the possible performance. An external antenna help here. Comparing the two zigbee coordinators (one bare pcb and the zigbee 3.0 plus) I have the same results.
Perhaps I got totally wrong tuned antennas which could happen (mentioned in some sources) and no way to measure the tuning.
But with my decent APs all wifi problems are gone (forever). So I don't have to spend any affords here.
Well this thread went off-topic in a hurry didn't it!
If you can't easily get some low-voltage wiring, maybe try a LiPo with a solar panel? Ups the expense of course but might well be more than enough, especially if you tune the sleep times such as going to sleep all night?
I also like the idea of using the lower-power ESP-now mesh network instead of plain Wi-Fi.
not having a webserver in every device web or app. 80€ per piece and the family is as happy as my IoT devices = money well spend.)
ok now I get it … you start small and add things …
