Big ESP32 + SX127x topic part 2

Monochrome OLED Displays Low-Power Tests

I have not been able to get ‘next to zilch’ results here. See below. Maybe redo some tests?

I performed tests on 9 OLED I2C display modules. 6x SSD1306 0.96" 128x64, 2x SSD1306 0.91" 128x32 and 1x SH1106 1.3" 128x64. Tests were performed with two different libraries: U8x8 (U8g2) and Adafruit SSD1306 + Adafruit GFX Library. The libraries made no difference for power usage.

Tests were performed with OLED display modules powered from 3.7V Li-Ion battery via HT7333 3.3V voltage regulator (different power source than MCU). Currents were measured with EEVBlog uCurrent Gold (mA range used for display on, uA range used for display off/power-save).

Results:

Display Type            All pixels off      50% pixels on       100% pixels on
                        Display on/off      Display on/off      Display on/off

A       0.96" 128x64    1.4mA / 13.7uA       8.7mA / 13.7uA     11.4mA / 13.7uA
B       0.96" 128x64    1.5mA / 12.8uA       9.6mA / 12.8uA     13.2mA / 12.8uA
C       0.96" 128x64    1.6mA /  7.7uA      14.7mA /  7.7uA     24.3mA /  7.7uA
D       0.96" 128x64    1.5mA / 32.5uA       9.9mA / 32.5uA     14.1mA / 32.5uA
E       0.96" 128x64    1.5mA /  7.0uA      16.4mA /  7.0uA     29.4mA /  7.0uA
F       0.96" 128x64    1.5mA /  8.4uA      16.1mA /  8.4uA     27.9mA /  8.4uA

G       1.3" 128x64     2.2mA /  7.4uA      22.4mA /  7.4uA     30.1mA /  7.4uA

H       0.91" 128x32    2.2mA /  8.3uA      16.7mA /  8.3uA     21.8mA /  8.3uA
I       0.91" 128x32    2.0mA /  8.1uA      18.7mA /  8.1uA     33.1mA /  8.1uA
Conclusions
  • It does not matter how many pixels are on when display is off/in power-save (as expected).
  • Quite some differences in power usage, both in normal display mode and with display off/low-power.
  • Lowest power usage of the 9 displays with display off/in power-save is 7.0 uA.
  • Highest power usage of the 9 displays with display off/in power-save is 32.5 uA.
  • For best low-power results one should switch off the display power.
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