2ElectricRCAircraftGuy's instructables
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- ElectricRCAircraftGuy commented on ElectricRCAircraftGuy's instructable How to Get an Arduino Micros() Function With 0.5us Precision3 months ago
- ElectricRCAircraftGuy commented on urucoug's instructable 7-day Option: How to Separate From the Air Force3 months ago
View Instructable »This information is so hard to find that I really think this article deserves more visibility. In an attempt to get it to be more "Googlable", I'm going to add some keywords in this comment that will hopefully get searched and found by the Google searchbots & web crawlers. Keywords: military separation, separate from the military, air force separation, separate from the air force, 7-day opt, 7-day option, seven day option, how to separate from the military, how to separate from the air force, how to seven day opt, how to 7-day opt, how to take the 7-day option, how to take the seven day option, how to leave the air force, how to leave the military, how to fill out paperwork to leave the military, what paperwork is required to leave the military, how to fill out paperwork t...
see more » - ElectricRCAircraftGuy favorited Repurpose Optical Drive With RPi by ollie2426 months ago
- ElectricRCAircraftGuy commented on Inquiring Mind's instructable How to Enlist1 year ago
For anyone interested in the flip-side: "How to Separate from the Air Force", which is also a difficult and complicated process, here's another useful instructable: https://www.instructables.com/id/7-day-Option-How-to-Separate-From-the-Air-Force/.
View Instructable »Yes, I don't know the details, but many foreigners, who are not US citizens, serve in the US military. Please do some online research to find out how. Feel free to reply here or edit your question directly to provide links and help to others once you learn how.
- ElectricRCAircraftGuy made the instructable 7-day Option: How to Separate From the Air Force1 year agoView Instructable »
I made it!!!!!!! YAAAAAAAAAY!!! I wish I would have had a nice tutorial like this when I was figuring things out, as not knowing how to do it also cost me an additional (and undesired/inadvertent) service commitment of > 2 years. Thanks for writing this up, as I think it will help a lot of people make more-informed decisions and more easily navigate the bureaucratic hell that exists all around them. It's hard enough trying to (1) make the decision to get out, (2) prepare for, qualify for, and obtain the skills necessary for a new job, (3) find a new job and, (4) make a new life for yourself outside the military, and yet sometimes the biggest hurdle (and also the FIRST hurdle)--which also feels insurmountable at times, is just figuring out *HOW* to try to get out. Most people don't re...
see more » - ElectricRCAircraftGuy followed urucoug1 year ago
SHORT ANSWER: Without testing it conclusively, I speculate 5us is the shortest pulse that can be measured by an ATmega328 mcu running at 16Mhz.-------------------------LONG ANSWER:Nick Gammon, an Arduino expert I've learned a lot from, states here (https://gammon.com.au/interrupts), that it takes around "4 μs" to enter an ISR (Interrupt Service Routing, or interrupt handler), and "around 5 µS to enter and leave an ISR". In order to measure a pulse, you need to interrupt on a pin change at the start of the pulse, enter the ISR, grab a timestamp (or use the input capture register if using the Timer 1 input capture feature, which is the best way to do it), and exit the ISR. Then, you need to do the same thing on the trailing edge of the pulse. Since it takes 4us to ente...
see more »SHORT ANSWER: Without testing it conclusively, I speculate 5us is the shortest pulse that can be measured by an ATmega328 mcu running at 16Mhz.-------------------------LONG ANSWER:Nick Gammon, an Arduino expert I've learned a lot from, states here (https://gammon.com.au/interrupts), that it takes around "4 μs" to enter an ISR (Interrupt Service Routing, or interrupt handler), and "around 5 µS to enter and leave an ISR". In order to measure a pulse, you need to interrupt on a pin change at the start of the pulse, enter the ISR, grab a timestamp (or use the input capture register if using the Timer 1 input capture feature, which is the best way to do it), and exit the ISR. Then, you need to do the same thing on the trailing edge of the pulse. Since it takes 4us to enter an ISR, I speculate the shortest pulse you could measure is 5us. Otherwise, the pulse will be over before you can even grab a timestamp from the leading edge of it. An Arduino can easily output a pulse, using the Output Compare registers in a timer, of 62.5ns, however, since that is the time it takes for 1 clock tick on a 16MHz clock, so this could be tested with 2 Arduinos where 1 generates a pulse anywhere between 62.5ns and 20us or so, and the other tries to read this pulse until it no longer can. Anyway, without testing it conclusively, I speculate 5us is the shortest pulse that can be measured by an ATmega328 mcu running at 16Mhz. Let's walk through what this might look like: at 0us the edge occurs and the interrupt flag is triggered. At 4us you enter the ISR and store the timestamp (of 0us if reading the Input Capture register, or of 4us if reading a raw timestamp from a timer/counter). At 5us you exit the ISR, and the trailing edge of the pulse occurs, tripping the interrupt flag. At 9us you enter the ISR, and store the timestamp (of 5us if reading the Input Capture register, or of 9us if reading a raw timestamp from a timer/counter). At 10us you exit the ISR. Your main loop does the calculation of ending_timestamp - beginning_timestamp and you calculate 5-0 = 5us in the Input Capture case, or 9-4 = 5us in the raw timestamp case. Perhaps I'm off a little and it would be more like 6us, but like I said, this could be tested. In either case, being able to do anything better than probably 20us or so would require knowledge of everything I said above, plus a very tight control over all interrupts and processes happening on the microcontroller to ensure that measuring the pulses takes highest priority, even possibly requiring turning on nested interrupts to ensure this interrupt measuring the pulse can interrupt other interrupt handlers (ISRs). I hope that helps. Someday perhaps I'll actually do this test, get conclusive results, and post them on GitHub. Could be interesting, though I've personally never needed to measure anything < 20us ~ 30us or so yet, and usually measure more like 500us or more. Having said all that, my library here is *not* optimized to measure 5us pulses. It is optimized to measure 500~2500us pulses, and probably wouldn't like anything less than 20~30us or so (guestimated).
SHORT ANSWER: Without testing it conclusively, I speculate 5us is the shortest pulse that can be measured by an ATmega328 mcu running at 16Mhz.-------------------------LONG ANSWER:Nick Gammon, an Arduino expert I've learned a lot from, states here (https://gammon.com.au/interrupts), that it takes around "4 μs" to enter an ISR (Interrupt Service Routing, or interrupt handler), and "around 5 µS to enter and leave an ISR". In order to measure a pulse, you need to interrupt on a pin change at the start of the pulse, enter the ISR, grab a timestamp (or use the input capture register if using the Timer 1 input capture feature, which is the best way to do it), and exit the ISR. Then, you need to do the same thing on the trailing edge of the pulse. Since it takes 4us to ente...
see more »SHORT ANSWER: Without testing it conclusively, I speculate 5us is the shortest pulse that can be measured by an ATmega328 mcu running at 16Mhz.-------------------------LONG ANSWER:Nick Gammon, an Arduino expert I've learned a lot from, states here (https://gammon.com.au/interrupts), that it takes around "4 μs" to enter an ISR (Interrupt Service Routing, or interrupt handler), and "around 5 µS to enter and leave an ISR". In order to measure a pulse, you need to interrupt on a pin change at the start of the pulse, enter the ISR, grab a timestamp (or use the input capture register if using the Timer 1 input capture feature, which is the best way to do it), and exit the ISR. Then, you need to do the same thing on the trailing edge of the pulse. Since it takes 4us to enter an ISR, I speculate the shortest pulse you could measure is 5us. Otherwise, the pulse will be over before you can even grab a timestamp from the leading edge of it. An Arduino can easily output a pulse, using the Output Compare registers in a timer, of 62.5ns, however, since that is the time it takes for 1 clock tick on a 16MHz clock, so this could be tested with 2 Arduinos where 1 generates a pulse anywhere between 62.5ns and 20us or so, and the other tries to read this pulse until it no longer can. Anyway, without testing it conclusively, I speculate 5us is the shortest pulse that can be measured by an ATmega328 mcu running at 16Mhz. Let's walk through what this might look like: at 0us the edge occurs and the interrupt flag is triggered. At 4us you enter the ISR and store the timestamp (of 0us if reading the Input Capture register, or of 4us if reading a raw timestamp from a timer/counter). At 5us you exit the ISR, and the trailing edge of the pulse occurs, tripping the interrupt flag. At 9us you enter the ISR, and store the timestamp (of 5us if reading the Input Capture register, or of 9us if reading a raw timestamp from a timer/counter). At 10us you exit the ISR. Your main loop does the calculation of ending_timestamp - beginning_timestamp and you calculate 5-0 = 5us in the Input Capture case, or 9-4 = 5us in the raw timestamp case. Perhaps I'm off a little and it would be more like 6us, but like I said, this could be tested. In either case, being able to do anything better than probably 20us or so would require knowledge of everything I said above, plus a very tight control over all interrupts and processes happening on the microcontroller to ensure that measuring the pulses takes highest priority, even possibly requiring turning on nested interrupts to ensure this interrupt measuring the pulse can interrupt other interrupt handlers (ISRs). I hope that helps. Someday perhaps I'll actually do this test, get conclusive results, and post them on GitHub. Could be interesting, though I've personally never needed to measure anything < 20us ~ 30us or so yet, and usually measure more like 500us or more. Having said all that, my library here is *not* optimized to measure 5us pulses. It is optimized to measure 500~2500us pulses, and probably wouldn't like anything less than 20~30us or so (guestimated).