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A very simple method (no floating point, no algebraic formulas) for linear conversion of sensor output data to human-understandable units.
— Example 1, temperature —
Two points are given: Sensor output 400 and 1200 correspond to 10 and 36.3 degrees Celsius respectively.
To get rid of floating point, we calculate Celsius in tenths of degrees:
Sensor Celsius 400 100 1200 363 (800) (263) (Distance)
Take: SensorZ = the given sensor value closest to zero (400) CelsiusZ = the corresponding Celsius value (100) SensorDist = distance between the two sensor values (800) CelsiusDist = distance between the two Celsius values (263)
The conversion then looks like this:
: >CELSIUS ( sensor -- celsius ) SensorZ - CelsiusDist SensorDist */ CelsiusZ + ;
The working forth definition is:
: >CELSIUS ( sensor -- celsius ) 400 - 263 800 */ 100 + ; ---------------------------------------------------------
NEGATE must be inserted after */ when increasing sensor values correspond to decreasing Celsius values.
— Example 2 —
Sensor Celsius
400 363
1200 100 (800) (263) (Distance)
: >CELSIUS ( sensor -- celsius ) 400 - 263 800 */ NEGATE 363 + ; ----------------------------------------------------------------
( an,jan2025)