I think I know what this pressure sensor is for. As the clothes-washer’s tub is filled with water, a tube to the bottom of the tub traps air, which is pressurized in proportion to the depth of the water. When the water reaches 300mm deep (or less, depending on the washer’s load-size setting) then the computer is supposed to turn off the water-fill valves and start agitation. This fill generally takes more than 1 minute, during which time the computer is doing almost nothing but waiting. So the computer chip can easily afford to spend >50% of its attention making measurements that take 0.1 second or longer. So it makes a lot of sense to count ticks during the time from one rising edge to the next. You could even time 16 cycles for each measurement, and compare multiple successive measurements for certainty.