"Riffle in a Bottle"
A lower-functionality / higher cost / Arduino IDE - compatible Riffle, based on Atmel328p.
- Requires FTDI cable for programming (e.g. Adafruit's "FTDI Friend") -- typically $15
- Includes uSD, flash memory, high-precision real time clock (DS3231) with coin battery backup
- Programmable as "Arduino UNO" in Arduino IDE
- runs at 3.3V and 16 MHz
- includes circuit for monitoring battery level
- board width allows device to be inserted through mouth of standard plastic water bottle (one with 20 mm diameter or greater)
- can run for several weeks (perhaps months) on 3 AA batteries, especially if low self-discharging batteries (like rechargeable Eneloops) are used
- Rough estimate of cost of parts that could be used to log temperature in a water bottle (not including shipping, or FTDI cable): $38 -- cost estimate here
- For a diagram of pin locations and optional configurations, please see this diagram in PDF format