Try this one.
The smallest board I have ever assembled using just a hot fan. A solar battery charger based on BQ25504 from a solar panel. Almost all components are 0402. Far too small for my liking, but can go under the solar panel.

Took me a while to make it though the idea is very simple. I took this jModule https://www.openhardware.io/view/20/jModule and a BMP280 i2c board (I have a few spare ones) and hooked them up Mini Pro (modified for the battery use) as well as the PIR and the battery compartment. I have to admit I am cheating here - I am using 2xAA Ni-Zn and they are 1.6V each giving me a stable voltage 3-3.2V throughout its life.
I had to do a little modification to the PIR to be able to work at 3.3v. It does work really well. Cannot say much about the battery life as it depends. Sleeping current is low, but the life really depends on how many times the PIR is going to be triggered.

Some photos at the end:

And the final product is ...(compared with DHT22)

@ahmedadelhosni said:

Is connecting the nrf directly to the pi causes any problems and u need to restart it ?

No, I have not had any big problems. The problem may only be the nrf24l01+ - I had to have a few changed plus fix the con to make it work. Wiring could be an issue. Also pay attention to CE pin.
CE Pin = Custom GPIO25 (I have Custom GPIO22) - this can be changed by the constructor

Excellent write-up

@neverdie Nope! I meant riding

My board waiting for a sensor from China

@jsiddall Yes, it does work. However, you may have to spend some time looking for a screen processor and schematics as Chinese are not providing much information.

1. Ask for schematics and have a look - there are four digital pins on your Arduino used for the SD card. Disolder these pins (some screens do not have them). These can be used for nrf24l01+ with Soft SPI (you have to enable it in MyConfig.h and change MISO, MOSO and SCK pins to correspond the pins you use).

2. Please do a bit research on Arduino forum. There is a sketch to help you to define a screen processor, there is a new library etc tons of information available.

3. It may take a while to do the whole research - there are many-many posts.

I have tried recently three different screens 2.8-3.2 (one similar to yours with analogue pins) with MySensors and all of them were working. Abeit one was very difficult - took me a while to
take it work due to lack of documentation.

I posted some pictures in "Scene Controller" under "Development" - please have a look

PS @mfalkvidd provided excellent links

Hello

Some of you may have followed discussion at low power lab about a new ARM module. Here we go available to purchase now:

https://lowpowerlab.com/2018/05/27/moteino-m0-released/#more-2427

Felix also introduced a modular system (“sandwich board”). Absolutely fantastic!

I have just soldered rfm69w module to the adapter. All works just fine

@hek I can confirm that Moteino Mega USB (and I think Moteino Mega as well) works out of the box:

Starting sensor (RRNNA-, 2.0.0-beta)
Radio init successful.
find parent
send: 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
find parent
send: 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:
Init complete, id=255, parent=255, distance=255
find parent
send: 255-255-255-255 s=255,c=3,t=7,pt=0,l=0,sg=0,st=bc:

@scalz My avr is 1.6.18 (newest)
I'll pull the latest dev and try again.

EDIT: Thanks @tekka - I have corrected pins_arduino.h for Moteino Mega (attached)

pins_arduino.h

Hi all,

Latest MySensors 2.3.2 on Moteino USB is giving the following compile errors:

"C:\\Users\\ashes\\AppData\\Local\\Arduino15\\packages\\arduino\\tools\\avr-gcc\\4.8.1-arduino5/bin/avr-g++" -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -MMD -flto -mmcu=atmega328p -DF_CPU=8000000L -DARDUINO=10607 -DARDUINO_AVR_ATmega328 -DARDUINO_ARCH_AVR "-IC:\\Users\\ashes\\AppData\\Local\\Arduino15\\packages\\arduino\\hardware\\avr\\1.8.4\\cores\\arduino" "-IC:\\Users\\ashes\\AppData\\Local\\Arduino15\\packages\\Moteino\\hardware\\avr\\1.6.1\\variants\\Moteino" "-Ic:\\Users\\ashes\\Documents\\Arduino\\libraries\\MySensors" "-IC:\\Users\\ashes\\AppData\\Local\\Arduino15\\packages\\arduino\\hardware\\avr\\1.8.4\\libraries\\SPI\\src" "-IC:\\Users\\ashes\\AppData\\Local\\Arduino15\\packages\\arduino\\hardware\\avr\\1.8.4\\libraries\\Wire\\src" "-Ic:\\Users\\ashes\\Documents\\Arduino\\libraries\\SparkFun_BME280\\src" "C:\\Users\\ashes\\AppData\\Local\\Temp\\arduino-sketch-9F678573572D7168587156F8AF298387\\sketch\\MotionSensor-lowlabs_v2_Nr2.ino.cpp" -o "C:\\Users\\ashes\\AppData\\Local\\Temp\\arduino-sketch-9F678573572D7168587156F8AF298387\\sketch\\MotionSensor-lowlabs_v2_Nr2.ino.cpp.o"
In file included from c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/MyCryptoAVR.h:25:0,
                 from c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/MyCryptoAVR.cpp:21,
                 from c:\Users\ashes\Documents\Arduino\libraries\MySensors/MySensors.h:65,
                 from C:\Users\ashes\Documents\Arduino\MotionSensor-lowlabs_v2_Nr2\MotionSensor-lowlabs_v2_Nr2.ino:17:
c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/drivers/AES/aes.cpp: In function 'AES_CBC_encrypt_buffer(AES_ctx*, unsigned char*, unsigned long)':
c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/drivers/AES/aes.cpp:525:1: error: unable to find a register to spill in class 'POINTER_REGS'
 }
 ^
c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/drivers/AES/aes.cpp:525:1: error: this is the insn:
(insn 288 325 289 11 (set (reg:HI 26 r26)
        (reg/v/f:HI 67 [ buf ])) c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/drivers/AES/aes.cpp:524 82 {*movhi}
     (expr_list:REG_DEAD (reg/v/f:HI 67 [ buf ])
        (nil)))
c:\Users\ashes\Documents\Arduino\libraries\MySensors/hal/crypto/AVR/drivers/AES/aes.cpp:525: confused by earlier errors, bailing out

Using library MySensors at version 2.3.2 in folder: C:\Users\ashes\Documents\Arduino\libraries\MySensors 
Using library SPI at version 1.0 in folder: C:\Users\ashes\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.4\libraries\SPI 
Using library Wire at version 1.0 in folder: C:\Users\ashes\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.4\libraries\Wire 
Using library SparkFun_BME280 at version 2.0.9 in folder: C:\Users\ashes\Documents\Arduino\libraries\SparkFun_BME280 
exit status 1

Compilation error: exit status 1

Any idea how to fix it? Using latest Arduino IDE and libraries

@flix I have seen these issues with some boards. Garbage is coming from the serial output and nothing is transmitted. Any sign of moisture ingress? You may try to re-solder the atmega328p with a hot gun but this most likely would required de-soldering all the wires from the board. Please check other things - bad soldering connection to VCC or GND may give a similar error. Maybe some bad soldering joints? You may want to try 9600 rate to make sure it works. On some boards to had to re-upload the boatloader (fake atmega328p IC).

The last resort of nothing works - change atmega328p. If the power is fine and no probs with the transmitter and no bad joints, most likely it is the IC

@mfalkvidd said in What happened to ceech?:

I don't know, but according to https://forum.mysensors.org/user/ceech last time online in this forum was September 2017.

His eBay shop is empty.
Not a good sign...

Hello,

I have written several messages but looks like he is not replying. Anyone knows if he has gone out of business or ...?

Thanks
Alex

@palmerfarmer said in Multiple BME280 sensor for Domoticz:

Hi,
I'm trying to build a node that uses x2 BME280 sensors for a whole house fan controller, one inside temp/hum and one outside. The BME280 has a selectable I2C address by grounding the SDO pin on the sensor. I have successfully tested this using the BlueDot_BME280.h library and sketches.
Problem I am having is turning this sketch into a working Mysensors node I can use in domoticz. I think I'm almost there but cannot see why i am getting an 'invalid use of non-static member function' message.
here is my hacked code...

I thought i would try and get it working with one BME280 first..

Check if you use } or { correctly.
I can see one mistake:

else
{
Serial.print(F("Temperature in Celsius from Sensor 1:\t\t"));
Serial.println(F("Null"));
Serial.print(F("Humidity in % from Sensor 1:\t\t\t"));
Serial.println(F("Null"));
Serial.print(F("Pressure in hPa from Sensor 1:\t\t\t"));
Serial.println(F("Null"));
{ (This should be } )

What Chinese are doing with this sensor which is used in a handheld air quality meters like this:

https://a.aliexpress.com/_UCY55

is this -> Li-Ion battery 3000-4000mAh
This would last hours. Not days.

Unless you want to use a car battery, I do not think there is a portable pm25 monitor able to work days without recharging.

@neverdie It does work under very extreme conditions (dark or very cloudy days for weeks), but I have not tested it extensively with internal lightning. The solar panel is very close to a window. I may be mistaken by I do not think LTC3108 is designed for low current (< 1 mA) application. BQ25570 is absolutely brilliant.

@neverdie said in Effective Solar Supercap Boost Charger for Small Solar Panel:

@ncollins said in Effective Solar Supercap Boost Charger for Small Solar Panel:

@neverdie they work super well. I've been testing them for a few months now, very reliable.

Great! Nice to have your feedback.

I had high expectations for Ceech's LTC3108 design:
https://www.ebay.com/i/331654685113?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=331654685113&targetid=809743845025&device=c&mktype=pla&googleloc=9028292&poi=&campaignid=6470262913&mkgroupid=80364172271&rlsatarget=pla-809743845025&abcId=1141166&merchantid=115344895&gclid=CjwKCAjw29vsBRAuEiwA9s-0B7exYA8yU9w--t63jcXP7QWO_f05DzJKNxw2XS6pwlLkPkfK1UYqkxoC084QAvD_BwE
but when I tested it, it turns out it needs about 5ma of current to run, which is at least 10x+ more than most small solar panels will deliver under even quite bright indoor lighting. Basically, if a panel can produce 5ma of current, the voltage will also be fairly high, thereby completely defeating the purpose of a chip like the LTC3108, which can be powered from 20mv. In my testing it took a minimum of 50mv and 5ma of current to get it to actually harvest any energy. 50mv would still be impressive, but the 5ma minimum is what kills its usefulness.

One of the best modules @ceech made was this one

https://www.ebay.co.uk/itm/BQ25570-thermal-solar-energy-harvester/332071662285?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3D759b68bcf5834d74bfa46f9df6b8ae4d%26pid%3D100010%26rk%3D1%26rkt%3D6%26sd%3D332393146893%26itm%3D332071662285%26pmt%3D0%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100010.m2109

It has been running non-stop for many months now

@skywatch I have the same sensor for months working like a charm. Sadly I had to disable it as I had one node and several sensors interfering with each other.

I will have to have the lightning sensor on a separate node

@manutremo

Activate a forced mode. I bet your sensor is in standby mode right now