Project: optimise

A colleague wrote a script for four rooms: each room has a heater with hysteresis and an alarm light, plus a display with the number of alarms. It is well commented, it works in the simulator – and it cannot be loaded. It has more than 128 lines.

The setup#

The rules#

1. Each room's heater on below 20 °C, off above 24 °C. The chip reads the previous state back from the heater.
2. The room's alarm light on below 15 °C, above 35 °C or without a sensor.
3. The display shows how many rooms have an alarm.

Measuring before and after#

Before you optimise, you measure. Afterwards you measure again. For the starter code and a solution with a name table it looks like this:

“Steps per tick” counts every line the chip runs through between two yield – comments in the loop included.

The lines shrink to a third, the steps per tick only to two thirds. In the starter code the many comment lines cost steps every tick – they disappear. In return the loop adds label, counter and jump back, four times per tick. Both are below 128, for this plant that is enough. With twelve rooms the loop would need around 220 steps and would have to run in portions as on Thursday.

Milestones#

1. Each room heats with hysteresis, independently of the others.
2. Each room reports cold and heat on its light.
3. The display counts the rooms with an alarm.
4. A missing sensor switches off its room's heater and reports an alarm.