BH1750 — ambient light¶
Being prepared
Chosen for the catalogue; the driver has not shipped yet. The figures below still need checking against the datasheet.
What it does¶
Measures how bright it is, in lux, with a response shaped roughly like the human eye's. Used to switch lighting, to dim a display so it is readable at noon and not blinding at night, and to prove that a machine's work area is actually lit to the level somebody promised.
Parameters¶
| Measures | Illuminance |
| Range | 1 … 65535 lx |
| Interface | I²C |
Bus and addressing¶
I²C, address 0x23 by default, or 0x5C with the address pin tied high. Two on one bus, no more.
Wiring¶
Four wires, and a clear view. Anything over the sensor — a smoked window, a sticker, dust — is part of the measurement whether you meant it to be or not.
In a project¶
To be written.
Traps¶
| Trap | What to do |
|---|---|
| Pointing it at the lamp | It then measures the lamp, not the room, and the control loop that dims the lamp becomes an oscillator. Point it at what is being lit. |
| Expecting a fast reading | A high-resolution measurement takes over a hundred milliseconds. This is a slow sensor by nature, which is fine — light is a slow thing to control. |