Project-Tally
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
Features:
- 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
Connectivity:
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
Power Consumption:
| 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.
Maximum input frequency:
| 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.
"Errors using inadequate data are much less than those using no data at all."
Concept and design by Bobby Schulz at Northern Widget
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.