The WORKBENCH part 1


connecting an 8 position pole switch to I2C with the help of
PCF8574 (8 position) or MCP23017 ( 2 x 8 position)

MCP23017 :

PCF8574 :



my virtual design is almost done… just a couple of weeks more


So I am looking for a small board to battery-power my nodes.
Perhaps this will do:
Previously tried this one:
But that has no discharge protection and as a result over-drains the battery.
Any other suggestions?


there exist also 'protected ’ 18650 battery’s, they have a build in protection circuit.

but think of this… when you drain the battery without protection, the MCU brownout will normally shut down the circuit :wink:
also I don’t trust these ‘protection’ circuits from the cheap dc/dc boards… 9 out of 10 don’t work as they advertise.
what you can do is measure (once a day ?) just after Tx the voltage of the battery and send an alarm byte when it’s getting to low.

(LoRaTracker) #813

Most of these ‘protected’ batteries and circuits can let the battery go as low as 2.4V.

I am not convinced its a good idea to let a Lithium battery repeatadly go this low …


hence the battery measurement at regular intervals :sunglasses:

another point I want to make ’ why using rechargable battery’s in low power nodes ’ if a node can run 2 / 3 years on a 3v battery…



these exist too (I used them in different cases) battery holder(s) for 18650 with build-in protection.


I was planning to run a mapper of this with a battery. Let the battery charge overnight and then run it for the best part of a day until the battery dies.
Turns out the amount of parts I would need would for this makes it close to the price of a board with mcu, tx and charger circuit in one.
So another option I would like to explore is to put a mapper/tracker in a boat that would run off the 12V battery but also has a backup. We have a plan to combine a ttn mapper with an anti-theft tracker in a boat and I do not want to fully deplete this guy’s boat battery plus a backup battery would be nice.


this is an interesting charge dc/dc converter to




I remove the red (charging) and green ( full) led and extend wires to a red/green pannel led so that I can see on the case if the battery is full.
module works perfect if you need 5v out

complete dc/dc 3.7 v in / 5 v out rechargable power unit with protection.
just connect to an adapter overnight… led switches from red to green when full

(Ssozonoff) #818

The weather ball :slight_smile:

It has vents at the bottom which lead to a chamber with an SHT-31D sensor in it.

Using the Grasshopper from Tlera Corp which I have fallen in love with + no fuss Arduino library with a great Lorawan stack. I am still considering various mounting options…



yours is the outdoor version of Oliver‘s coconut


’ green ’ nodes … love it :sunglasses:


That is indeed the way to go, thank you for the info.


Very nice but black which very easily (over)heats up in direct sunlight, effecting the temperature measurement.

(Jens) #823

Hey @BoRRoZ
Where you get the rifle with the seal (top of the pic)? Is it 5,5/2,1?



rifle ?

(Jens) #825

Thank you.

BigG translatet Buchse = Rifle.



Hallo all,

for outside work you can better use after the test install with Ty-Raps, some Stainless steel perforation mounting band.




you have a link to ?




Dragino LoRa Mini arrived … and its really ’ mini ’ for a complete 328p +sx1276 node