Display fonts missing µ and ³ glyphs, plus English localisation errors

Firmware version: 01.00.00.00

The display currently uses:

- ug/m3 for PM2.5 and PM10
- mg/m3 for eTVOC and formaldehyde

The typographically correct unit labels would be:

- µg/m³
- mg/m³

Actually to be real formal SI units should really be:

- µg m⁻³
- mg m⁻³

but the previous version is also allowed

When I have experimented using UTF-8 strings are used, the device displays missing-glyph boxes.
The display fonts appear not to include:

- U+00B5 MICRO SIGN
- U+00B3 SUPERSCRIPT THREE

I believe inclusion of these glyphs in the small UI font used for the measurement
units would correct this issue. Including U+03BC GREEK SMALL LETTER MU as well may improve compatibility.

There are also two English proofreading errors in firmware 01.00.00.00:

- "Mondy" should be "Monday"
- "wednesday" should be "Wednesday"

For anyone interested in a patched firmware that corrects these and fixes date format issues see my other issue on UK date as I have also uploaded a firmware that shows proper SI units which is linked from there.

Start by locating the small UI font assets and the firmware's English weekday strings, then inspect how the measurement-unit labels are encoded and rendered. Done means the display renders µg/m³ or mg/m³ without missing-glyph boxes, and the visible labels read “Monday” and “Wednesday” in firmware 01.00.00.00.

Written by the indexing model from the issue text.