Joe Plocki (turbojoe)
High Speed Firecracker Explosion Photographic Appliance
Continued from the other day, some of the initial circuit has changed, and now includes a built-in sound trigger. Except that the sound triggering is giving me fits... that part of the circuit is analog, and the logic, of course, is digital. Apparently, the microcontroller and I have differing views of what "rising edge" means, and the trigger causes the flash interrupt well before it's supposed to. So far, I've not been able to work it out.
I'm sure I will, though. The problem is probably in my code, with a second choice being the analog interface into the digital logic section. Anyway, this is the most complicated circuit/microcontroller code project I've ever worked on, and I've had surprisingly few issues with it, so far...
Anyway, since I don't have the photos I was building this to help capture, here's a description of what it does, when I think about it, blissfully absent from the hard reality... notes above describe the various parts.
Prefocus and compose the shot on the unsuspecting firework. Turn on the device, wait for the "ready" indicator light. Push the little yellow button. The shutter interface opens the shutter in bulb mode. Half a second later, the igniter circuit activates, cranking 4 amps through the rocket motor igniter. Since 2 amps should "guarantee" ignition, that should be good. Once the igniter circuit goes hot, the sound trigger starts listening for the boom. When it hears the boom, it signals the microcontroller to cut power to the igniter, pop the flash, and close the shutter on the camera. Then it recycles, waiting for the next one. Except, of course, it doesn't... it doesn't do that, at all.
Unfortunately, I've already begun to get distracted... it occurred to me today that I could probably make a cheap-o 16-24 channel logic analyzer with an Atmega16. That's very appealing to me, because sometimes an analog scope isn't enough. It's painful to work out chip-to-chip communications with a 2-channel scope. I may switch over and work on that for the rest of the night. Of course, I'll have to implement a USB interface, and write a Windows app to actually use it, so there's like a zero percent chance I'll have it done this weekend. Which means that by next weekend, I'll be on to something else...
update!!! Live fire trial run tomorrow!!! Fixed both known issues (both were code - one was a misread register name, the other was a lack of understanding of how code optimization can jeopardize variables)!!!
High Speed Firecracker Explosion Photographic Appliance
Continued from the other day, some of the initial circuit has changed, and now includes a built-in sound trigger. Except that the sound triggering is giving me fits... that part of the circuit is analog, and the logic, of course, is digital. Apparently, the microcontroller and I have differing views of what "rising edge" means, and the trigger causes the flash interrupt well before it's supposed to. So far, I've not been able to work it out.
I'm sure I will, though. The problem is probably in my code, with a second choice being the analog interface into the digital logic section. Anyway, this is the most complicated circuit/microcontroller code project I've ever worked on, and I've had surprisingly few issues with it, so far...
Anyway, since I don't have the photos I was building this to help capture, here's a description of what it does, when I think about it, blissfully absent from the hard reality... notes above describe the various parts.
Prefocus and compose the shot on the unsuspecting firework. Turn on the device, wait for the "ready" indicator light. Push the little yellow button. The shutter interface opens the shutter in bulb mode. Half a second later, the igniter circuit activates, cranking 4 amps through the rocket motor igniter. Since 2 amps should "guarantee" ignition, that should be good. Once the igniter circuit goes hot, the sound trigger starts listening for the boom. When it hears the boom, it signals the microcontroller to cut power to the igniter, pop the flash, and close the shutter on the camera. Then it recycles, waiting for the next one. Except, of course, it doesn't... it doesn't do that, at all.
Unfortunately, I've already begun to get distracted... it occurred to me today that I could probably make a cheap-o 16-24 channel logic analyzer with an Atmega16. That's very appealing to me, because sometimes an analog scope isn't enough. It's painful to work out chip-to-chip communications with a 2-channel scope. I may switch over and work on that for the rest of the night. Of course, I'll have to implement a USB interface, and write a Windows app to actually use it, so there's like a zero percent chance I'll have it done this weekend. Which means that by next weekend, I'll be on to something else...
update!!! Live fire trial run tomorrow!!! Fixed both known issues (both were code - one was a misread register name, the other was a lack of understanding of how code optimization can jeopardize variables)!!!