Probes in the code

The workshop heater switches. But how often? Too often, because the hysteresis is too narrow? Without measuring you are only guessing. A probe is a line that writes an intermediate value to a place where you can see it – like a meter you clip onto a wire.

Three places for a probe#

Write the value the way the chip sees it, before any conversion. That is exactly when NaN, Kelvin instead of Celsius and doubled sums stand out immediately.

LineNumber: where is the chip?#

LineNumber of a housing is the line its chip is on right now. A second chip can read and display it. If the display shows the same line in a waiting loop for minutes, the chip is waiting there for a condition that never happens – for example for a door that is already open.

define GEHAEUSE HASH("StructureCircuitHousing") # IC housing
lbn line GEHAEUSE HASH("Schleusenchip") LineNumber Average
sbn ANZ HASH("Sonde1") Setting line

In normal operation the value changes all the time, usually it is the place where the chip waits for the next tick. LineNumber becomes meaningful when it stops moving.

Adding counters#

Many questions are “how often?”: how often does the loop run, how often does the heater switch on, how long does a state last? A counter answers that.

add passes passes 1     # counts every tick
sgt edge on old           # 1 only on a change from 0 to 1
add starts starts edge
move old on

The edge counter only counts switching on, not every tick with the heater running. If it rises every few seconds, the hysteresis is too narrow.