Day and night

Outside the sun goes down and the path to the landing pad lies in the dark. A daylight sensor (StructureDaylightSensor) tells the chip when it is time for light.

What the sensor reports#

For day and night Activate is enough. The value applies to the sensor itself: if it stands in the shadow of a building, it is night for it. Build it in the open, with a view of the sky.

SolarIrradiance tells you more. In bad weather the value drops without Activate jumping to 0. If you want light already under a dull sky, compare this value with a limit.

lbn sun SENSOR HASH("Sonne") Activate Average
seqz dark sun              # 1 = no sun
sbn LAMP HASH("Aussenlicht") On dark

On failure, better bright#

If the sensor is missing, Average returns NaN and seqz turns it into 0. The light would stay off, and for outdoor lights that is the wrong direction. A light that burns needlessly during the day costs a few watts. A dark path can cost you a suit.

snan missing sun
or dark dark missing       # no sensor: light on

A schedule with a counter#

Not everything follows the sun. Grow lights, for instance, should have fixed times. For that you count ticks. A pass with one yield lasts one tick, that is 0.5 s:

add time time 1
mod time time PERIOD       # 0 to PERIOD-1, then from the start
slt on time ON             # the first ON ticks: on

mod resets the counter to 0 after PERIOD ticks. With PERIOD 7200 and ON 4800 you get a one-hour cycle with 40 minutes of light.

A counter can also measure: how long has it been dark? Count up while it is dark and reset it to 0 in sunlight. A multiplication saves the jump:

add ticks ticks 1
mul ticks ticks dark       # in sunlight: times 0