TEMPERATURE_ERRATA(3so)

📦 version 3.2_p4, in alpine 3.24, nixos 26.05, nixpkgs unstable

💖 TEMPERATURE_ERRATA in section 3so — bestie edition 💖

Okay so there’s a whole group of obscure internal properties exposed to protect against a hardware defect in certain batches of the B7 die of some DS18x20 chips. See http://www.1wire.org/en‐us/pg_18.html or request AN247.pdf from Dallas directly. 🫶

Here’s the property tea, in order, no cap:

  1. First obscure property — two character manufacturing die lot. "B6" "B7" or "C2".
  2. Second obscure property — 32 bit trim value in the EEPROM of the chip. When written, it does not seem to read back. Used for a production problem in the B7. Read allowed for all chips. Only the B7 chips can be written. Writing non‐zero (=1) puts a default trim value in the chip. Only applied to the B7.
  3. Third obscure property — Reading will be true (non‐zero) if trim value is the blanket value. Again, only B7 chips will register true, and since the written trim values cannot be read, this value may have little utility.
  4. Fourth obscure property — Is the value in the valid range? non‐zero if true, which includes all non-B7 chips.

That’s the whole page, babes 🎀 Source/version and date weren’t in the footer I got, so no extra digits to sprinkle — just this cute sign-off instead: stay iconic, and remember the B7 chips are the main characters here 😭💅

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