Several questions (language comparison)

[Ether]

Originally Posted by Radical Pi

Team 639 used a rotating kicker and had a IR sensor that pulsed a Digital Line whenever the kicker reached a certain angle.

Why did you need an ISR to handle this? Was 20ms not fast enough?

[Radical Pi]

Originally Posted by Ether

Why did you need an ISR to handle this? Was 20ms not fast enough?

Our kicker rotated and launched outward when the kick button was pressed. The rotations were at an extremely high speed. To prevent the kicker from coming out at an unpredictable and generally unfavorable angle, we used the sensor as an interrupt to make sure the kicker could come out at a predictable angle. As the speed of the rotator increased, the range of angles for a good kick decreased, so the room for error in the timing of the code wouldn't allow for timing of the kick to occur in the main loop. The interrupt checks a flag for whether to kick, and also will delay the kick as needed to compensate for the speed of the kicker (without the extra timing code, the kicker only works around 75% power)

[Ether]

Originally Posted by Radical Pi

The interrupt checks a flag for whether to kick, and also will delay the kick as needed to compensate for the speed of the kicker (without the extra timing code, the kicker only works around 75% power)

What is the worst-case execution time of the ISR from the time it receives control until it returns? Do you enable interrupts in the ISR, or leave them disabled?

[Radical Pi]

Originally Posted by Ether

What is the worst-case execution time of the ISR from the time it receives control until it returns? Do you enable interrupts in the ISR, or leave them disabled?

I'm not sure of the exact number as I didn't write the timing code for it, but I think the time to run it is almost nothing. The only slow operation is the wait to delay the kick, but that would be a very small wait.

The interrupt is setup through WPILib, so I have no idea if interrupts during interrupts are enabled (never seen any problems though).

[Ether]

Originally Posted by Radical Pi

I'm not sure of the exact number as I didn't write the timing code for it, but I think the time to run it is almost nothing. The only slow operation is the wait to delay the kick, but that would be a very small wait.

When you say "very small" do you mean, say, a few microseconds?

Or are you talking milliseconds?

[Radical Pi]

Originally Posted by Ether

When you say "very small" do you mean, say, a few microseconds?

Or are you talking milliseconds?

I think it's in the single digit milliseconds, but again I'm making a guess from the speed of our kicker