This circuit allows many uses :
It runs from battery. There is a CR2032 holder on bottom, but it can also be powered with 2xAA batteries, on a separate header.
You can also directly provide the 3.3V on another header.
There is 2 inputs : both have pull-ups pads to solder a resistor, but are optionnal (if you prefer to use atmega internal resistor).
The power stage uses a MAX1724EZK33+, which converts input voltage from 0.8V to 3.3V to fixed output of 3.3V.
The radio module used is a RFM69(HW). I also made a very similar version for the RFM69HCW, because HopeRF did a mistake and sold me 50pcs of the wrong radio module ;). It uses almost the same components, except I removed the boost converter.
Circuit size is 50x30mm, which is about the same size of 2xAA batteries. You can the place it almost everywhere !
Component selection There is different ways to power this device :
Programming Warning ! The board isn't drilled big enough to use standard ICSP headers ! Instead, I made a simple adapter with pogo pins (pictures coming soon). Just hold the adapter with a hand firmly on the board, and hit "upload" with your second hand. You'll also need an USBASP or equivalent programmer (no USB adapter on the board !)
Usage You can use the device multiple ways :
|Qty||Value||Device||Package||Parts||Description||MF||MPN||Aliexpress or Ebay link|
|1||RFM69HW||Or RFM69W if you don't care about high power.|
|6||Pogo Pins||to use ICSP !|
|1||AMS1117||...or equivalent, if you plan to supply more than 4.5V|
|1||MAX1724EZK33||if you plan to power with less than 3V|
|1||1206 inductor 10uH||if you plan to power with less than 3V||Ebay: 50x Inducteur Montage en Surface 1206 SMD SMT Surface ...|
|1||CR2032 holder||if you plan to power with a coin cell||Ebay: K7498 20pcs White Housing CR2032 SMD Cell Button Batte...|