====== WIP ======
FIXME

===== BOM =====

  * 1 × ATmega328P
  * 1 × 28pin IC socket
  * 1 × LM317T
  * Resistors
    * 1 × 470Ω
    * 1 × 680Ω
    * 1 × 3.3kΩ
    * 1 × 47kΩ
  * Capacitors
    * 1 × 10µF Electrolytic
    * 1 × 100µF Electrolytic
    * n × 0.1µF (104) Ceramic
  * 3 × Rectifying Diode 1N4001

===== Circuit =====

==== Voltage regulator ====
The voltage regulator circuit is based on the LM317, mainly because this is what I currently had handy, that would give me a comfortable margin of error. There can be up to a 40V difference between input and output voltage, which means this circuit should be able to handle a input voltage of up to 43V between GND and V<sub>BAT</sub>

{{ :oddstr13:node:atmega328:batterymonitor_lm317t_circuit_diagram.png?direct&480 | Circuit diagram }}
{{ :oddstr13:node:atmega328:batterymonitor_lm317t_top.png?direct&480 | Top view }}
{{ :oddstr13:node:atmega328:batterymonitor_lm317t_bottom.png?direct&480 | Bottom view }}

The values of R1 and R2 where chosen from resistors I had available, using this [[http://www.muzique.com/schem/lm317.htm|LM317 Voltage Calculator]]. I was aiming for something around 3.3V.

R1=470Ω R2=680Ω, which gives a output voltage of about 3.06V, which is acceptable for all of the components.

  * RFM69HW 1.8V--3.6V.
  * ATmega328P 1.8V--5.5V.
  * DS18B20 3V--5.5V.

V<sub>BAT</sub>S

===== Programming =====
{{ :oddstr13:node:atmega328:batterymonitor_programming_top.png?direct&480 |}}

^         ICSP header         ^^^^
^#^Function        ^AVR#^AVR Name^
^1|SCK             |  19|PB5     |
^2|MISO            |  18|PB4     |
^3|GND             |   8|GND     |
^4|V<sub>SYS</sub> |   7|VCC     |
^5|MOSI            |  17|PB3     |
^6|RESET           |   1|PC6     |
^7|V<sub>BAT</sub> |      NC    ||

====== External links ======

  * http://www.muzique.com/schem/lm317.htm
  * http://www.csgnetwork.com/antennagenericfreqlencalc.html
  * http://www.st.com/web/en/resource/technical/document/datasheet/CD00000455.pdf