Math operations execution time

[Jumper]

Hi,


I am far from a math genious but WHY do you even calculate the height?

The ADC value is the only thing that changes in your formula and then I think you can use the raw value.

I inserted your formula in an Excel sheet and I am not really sure it is correct. When ADC is 0 your calculated height is 8687 and with ADC 256 the height is 6025. So it seems as long as the adc value is getting smaller the height goes up. A quick look in the datasheet gives the formula

Vout = Vs * (.009*P-.095) where P is in Kpa and Vs=5.1V Looking at the graph this makes Vout vs Kpa shows that when the Kpa becomes lower the Vout should be lower.. so you need to double check your formula..

I still think you can use the raw adc value to find when the rocket stops going up. The higher it goes the smaller the adc value will be and when the ADC gets bigger again it is time to activate the parachute servo.


BUT

ADC sampling is not a one shot activity (average the values or allow for a threshold or it will not be very stable)

Then you can also store the adc value where the servo was activated in the EEprom you you later can know how high you went.

Why do you need speed for this? When the rocket has slowed down because it can get any higher it will slowly start to accelerate towards the ground .. and the first 50-100 meters it falls will take at least 5-6 seconds. I am a skydiver and we usually dont deploy our parachutes until we have reached a reasonable speed to allow the parachute to open in a more reliable way. If we deploy it too early it can open too slowly and twist the lines and that is not that great.