“A 4-channel 0 to 27V voltmeter with tiny OLED display. Uses ATTINY1614 MPU (could be 1604) and 72x40 0.42in I2C OLED module. Also shows inputs as TTL levels: 0, 1 or indeterminate.
Notable design features
- Size 18x21x11mm
- Autoranges six levels for optimal accuracy
- OLED unplugs, allowing the MPU to be programmed via the same header
Function Overview
The MPU ADC (10-bit) reads voltage data from 4 channels and shows them on an OLED display.
Features:
- 0-27V range. 1mV resolution for V<1V.
- 3.3-12V supply. Reverse polarity protection.
- Accuracy c.1% (can be improved by calibration). May deteriorate - depends on resistor quality.
- Temperature variation is mostly dependent on the resistors. The MPU ADC is +/-0.1% over 0 to 40C.
- Positive voltage only. Over voltage indication. +/-100V input tolerant.
- 1.1Mohm input impedance (or 1.1Mohm in series with 30pF when V<2.5V).
- Sample rate c.10/s, configurable
Display operation
- Displays version info and help screen on power-up. Then shows 4 lines of voltage and one line with logic levels”