Some of my tips (noob alert) that I've gathered in my travels so far for this temp Slim node
- Burn the bootloader onto the ATMega328 first! (here is a guide for Arduino as ISP)
- Check the capacitor polarity before you solder it (the 4.7uF electrolytic capacitor, the others don't matter)
- I prefer using strips for the Atmega (see here) as you'll have more clearance for the capacitors which sit underneath (there is a caveat to this however, in that if you're not sure if you've got/burnt a bootloader onto the ATMega, using strips there is no going back, whereas with the chip socket, you can remove the ATMega). Update I think, for me anyway, if you're confident that the ATMega has been bootloaded successfully, I still prefer strips, however if you're unsure what you can do is use the socket and just sit it higher in it's position to get a decent clearance.
- The bill of materials (BOM) is here and also helps with figuring out which pieces go where
- Solder the capacitors, wires for Si7021 (with si7021 attached) and FTDI pins to the board first, then the strips + AtMega328p (see below), then the NRF last to the board. I found that the FTDI pins facing straight up were best for the box I was going to put it in
- Solder the strips to the ATMega first, then to the board
- Check the size of the box/fitting you are going to mount this in before you do all the above!
- Check that you are putting the ATMega chip the right way on the board, the notch should be facing the pins for the FTDI.
- Check continuity of the pins from the ATMega to the board pins underneath, I found the ATMega to strips were the most difficult to solder, and after I tested continuity I found a single pin which didn't have connection, so I added some more solder to this pin.
- Don't forget the resistor at R1 (I soldered this to the underside of the board, less by choice and more by the fact that I forgot about it, but I guess the preference would be the same side as the capacitors)
- I strongly advise buying the 3.3v ready si7021 temp sensor (here) as the modification to the 5v version is quite difficult for a newbie (the components are quite small) and you'll probably mess it up like I did.
General soldering tips
12) Practice soldering first, some of the joins are a little challenging and it took me a few attempts to get the hang of it
13) Get a decent size tip, my first was a bit large