A minimal ultra low power digital event counter, designed to be a counterpart to a traditional data logger to measure and average rapid events like an anemometer reading
- On board super capacitor (can be self powered between readings/recharge)
- Extreme low power
- 3.3/5v capable
- I2C interface
- Measure up to 65536 (2^16) events before rollover
- Integrated input pullup/pulldown
- Integrated input conditioning (allows for non-binary inputs)
Using jumpers on bottom side of board, can configure input as pullup, pulldown (ultra low power mode), or direct input if driving from another device
Device can easily be interfaced to using I2C at either 3.3v or 5v (logic and power).
A library has been developed for interfacing with Arduino based devices: Tally Library
| Mode | Current @ 3.3v |
|---|---|
| Default | ~4mA |
| Sleep | <100uA |
| Switched | N/A1 |
1When the device is disconnected from the power bus, it draws no external power and runs off the on board super cap. Tested in pull up mode with 100Hz, 50% duty cycle switching input. Ran for 30 minutes, resulting in a consumption of ~ 0.275J of energy = 7.64e-5 Watt Hours -> 15.26 uW avg -> ~ 5uA @ 3v avg.
| Mode | Max Freq [kHz] |
|---|---|
| Pull Up | 16 |
| Pull Down | 10 |
| Direct, Square | 9 |
| Direct, Sine | 22 |
| Direct, Triangle | 22 |
Measured using a function generator with a 2.5v amplitude for push pull tests, and driving an appropriately selected MOSFET for the pull up and pull down variations to act as an analogous switch, once again driven by a function generator.
Concept and design by Bobby Schulz at Northern Widget
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.