Hardware

It needs a minimum load onthe output, in order to function correctly. If this minimum requirement is not met, the output couod become unstable, and self oscillate. I've Seen this with an electronic transformer for halogen lights, where i use led lamps instead. Needed 1-2 halogen spots on it (it supplies 5 spots in total) in order for the electronic transformator to work correctly

@Dheeraj Personally I think it's interesting, but I also know it¨s been rejected in earlier discussions. It requires calibration, low-power and low activity arduino use. And even then, the accuracy isn't very impressive. I would still like to play a little and maybe use it as a complement in some projects. We'll see.

Thank you. And what about the low ESR capacitors?

Thank Sensor ready work. (I have not valid binary Optiboot) [image: 1427989664063-20150402_172032.jpg]

@jendrush At the moment 5v use one of the [image: 1427712052724-20150330_160334.jpg]

@m26872 This is mostly a matter of opinion. There are several options available. Personally, I will design so that I have three options to choose from depending on the sensor type (and long term measurement data)

this will work i think, but not sure what will happen, after removing the regulator from the pro (http://iot-playground.com/2-uncategorised/9-arduino-low-power-sensor). I hate it, that i don't find any useful documentation about my usbtiny grml :disappointed:

Yes, Nano is a bit bigger, but have own usb-serial chip so you can program it directly and have onboard 5-3.3 output. Keep forgetting that:) So if size is not an issue, got with the Nano...

@dakky No, it can not set fuses.. You need a ISP programmer for that. There are lot's of "cheap" isp programmers around, even an arduino can be made into a ISP programmer.

I don't know .. but ideally is if nrf24l01 set ack with payload .. and this payload will contain random number or rtc time .. encrypted with xtea . all node or repeater if receive ack then got this number or rtc time .. and use in next packet .. nrf24l01 chip can make 50%work alone .. node if send data packet then wait for hardware ack . and this ack can contain payload .. this payload will be starting point ..gw will generate actual payload for ack sequence .. It's just idea ..

Of cource it's powered down :-) - but is his done by a sw-command via SPI (and also the pwr-up) or by transistor ? I'm surprised about the quality of the rNF - the power down seems very good?

Absolutely

That lib only supports HW SPI(from what I can see) and I would need it for Pro Mini's. But tried it on a mega, almost same issue. Did some more testing with same result. I checked the datasheets , and from what I can see, it is depending on a stabel reference voltage. Was driving my pro mini with 5v and then regulating it to 3.3v for the MAX31855. So dataline was 5v and max31855 was 3.3. Even if this is within spec the macx31855 board I got was as cheap one, so it did not filter the voltage/data input for the chip.(Looks like the Adafruit board does?) Moving the regulator in front of it all, driving everything with 3.3v it's as stabel as could be expected. [image: 1426927325919-screenshot-2015-03-21-09.41.14.png] Green is a DS18B20, Blue a DHT21 and the black is the ThermoCoupler.

If the sensor and the gateway are at the same level or about the same level I think using a half-wave dipole or "rubber duck" antenna pointed vertically is a good idea. That will focus the energy in the horizontal plane and not into the ground or to the air giving about 2 dBi of gain.

It is possible to connect the radio, you can find instructions for example here. CE/CSN to any unised digital pin, IRQ not needed. However there are 2 pitfalls: voltage: You need to have 3.3v to power the radio. Pro Micro module is sold in 5V version or 3.3V version. 5V version don't have 3.3V pin output, so you have to arrange that by an external regulator. If you have 3.3V version, then it's fine for the radio, but such board is working on 8MHz, so it's not compatible with Leonardo target in Arduino IDE, you need to have hack that there. MCU there is different than Arduino Uno/Pro Mini, sleep modes are different; someone here reported that sleep is not working with MySensors, you can search here for experience with that. I made some helper PCBs for pro micro, you can check here. [image: upload-57ad0499-3d7e-4dfd-bfe1-b666f9b05fb8.jpg]

@Mickey What would be the use case? One can't do much with 4kB flash on the controller there.