first piece - kitchen sensor

Last week all needed parts arrived to start with the assembly of the first member of my home automation infrastructure.

This will be the kitchen sensor - i picked this because it involves many sensors and no control.

Imagined operation

If i walk into the kitchen…it should be aware of my presence; if the light condition are too dim - the two lamps should turn on…to supplement lighting to the specified level.

This means: when there is daylight; there would be already more than enough light, but when the sun goes down the lights should complement the existing light sources to reach the desired lumen level.


  • powered from 12v
    • 5v system (dsn-mini-360 stepdown)
  • motion sensor (HC-SR510)
  • photoresistor (GL5516?)
    • voltage divider using a 11K resistor
  • temperature/humidity sensing (DHT11)
    • needs a 4.7k pullup
  • able to communicate (nrf24l01)
    • needs 3.3v (ams1117)
  • some control (pro mini)

I’ve previously experimented with all the sensors (except the photosensor) - so i’ve planned my board; and soldered it in a rough 5 hour session…this was my first time I soldered an entire board.

I didn’t wanted to solder the parts directly into the breadboard…if i fry it; i want to easily reclaim the usable parts plus i might kill some component on the way - and plugging in the next one is much easier ;)

I must note that I even encountered a faulty stepdown regulator…i’m not sure what killed it…the heat when i soldered it; or I break it’s potentiometer with the bad screw driver…it ended up outputing the input voltage…so I inserted a new one.

Here is the front/back of the thing ;)

After I wired up almost everything…I checked for shorts a few times…i’ve found none ;)

I plugged it in and I loaded the nrf24 communication program…it worked when I powered the device from the ftdi header; but when I switched to batteries it didn’t wanted to work..because the led’s pin (13) is also used for SPI communication I wasn’t able to debug it much…

After a while I’ve turned to the arduino irc channel and described my situation…the suggestion was to add some capacitators for this tiny dsr-mini-360 regulator; to help it smoothen the voltage…because I don’t have any; I unplugged that small regulator and conneceted a larger LM2596 based step down, with a 220uF capacitator - and that solved the problem…so I should get a bunch of capacitators ;)

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