STRUCT SHT21(9)

✨ NAME ✨

struct sht21 — the SHT21 device specific data 🎀 like, this is the little bundle of everything the driver remembers about your SHT21 sensor, iykyk

(this one lives in the Kernel API Manual, bestie — you're in the right place 💖)

🌸 SYNOPSIS 🌸

struct sht21 {
    struct i2c_client *client;
    struct mutex lock;
    unsigned long last_update;
    int temperature;
    int humidity;
    bool valid;
    char eic[18];
 };

Ok so that's the whole struct, character for character, no cap 📋 — the fields are explained down below, keep scrolling bestie 👇

💅 Members 💅

• client — the I2C client device. that's the whole reason this thing exists fr fr 🦋
• lock — a mutex whose entire job is protecting the measurement values. do not skip the lock, it's giving bodyguard energy 🔥
• last_update — the time of the last update, measured in jiffies ⏰ (yes, jiffies, that's the unit, don't come for me)
• temperature — the cached temperature measurement value. cached!! as in, it's a stored value, not a fresh reading every time 🌡️
• humidity — the cached humidity measurement value, same deal 💧
• valid — only 0 before the first measurement is taken. so like, 0 = we have literally nothing yet, anything else = we've measured at least once ✅
• eic — the cached electronic identification code text, sitting in a char[18] 🏷️

lowkey important: temperature, humidity and eic are all cached — the struct is holding onto the last known stuff, bestie 🫶

🧚 SEE ALSO 🧚

• Kernel file ./drivers/hwmon/sht21.c
• sht21_temp_ticks_to_millicelsius(9)
• sht21_rh_ticks_to_per_cent_mille(9)
• sht21_update_measurements(9)
• sht21_temperature_show(9)
• sht21_humidity_show(9)
• eic_show(9)

go read all of those, they're the supporting cast and honestly they ate 👑

that's the whole page!! mwah 💋 this little struct drop comes courtesy of the ./drivers/hwmon corner of the kernel, dated October 2026 — iconic of it, honestly. periodt. 💜✨