Mulbin

Custom hardware / simpit repository. For people who take KSP a little too far.

609 posts in this topic

Posted (edited)

Logic Analyzers are awesome! I tried to troubleshoot my code for several hours, now my LA arrived and I fixed it in 2 minutes, I typed in the wrong value in the check for the first Bit (at the beginning of the message a 15ms long HIGH is sent and on the receiver side the controller checks for every high it gets if it is longer than 12ms and if it is, it thinks thats the start of the message. I typed in 1,2ms by accident and saw it immediately with the LA!

 

@richfiles I would love to get a tape but shipping to Germany would be more expensive than hiring an artist to draw it by hand I assume.

If it is ok with being folded you could put it in a letter...

What does 1 tape cost without any shipping?

Edited by Pvt. KASA

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16 hours ago, Pvt. KASA said:

Logic Analyzers are awesome! ...
 would love to get a tape but shipping to Germany ... What does 1 tape cost without any shipping?

I have an old Gould Biomation Logic analyzer that I've always wondered if I could ever repair. It's ANCIENT... Maybe late 1970s or VERY early 80s. It has a CRT screen... The catch... It's mostly built using small scale logic, early memory chips, ECL (emitter coupled logic) gates... Really old stuff! The thing is just HUGE! :D I got it for free ages ago, and ultimately, I've decided my next oscilloscope MUST be a mixed signal oscilloscope, with a logic analyzer function built in. A modern analyzer would be more useful, both function wise, and for not taking half my workbench. For me, I'd want to be able to use it to analyze pulse propagation in the neural networks for my robots, in relation to motor drive outputs. Also probably Arduino stuff... :wink:

Regarding the tape, I don't yet know what the costs will be. My tape meter will be 3 feet long (just short of 1 meter), simply because that's how long my tape is. Truth is, if i wanted to work with other materials, i might have simply done a much longer meter, with even more divisions. Since my meter is a fixed length loop, I had to work within the available space.

At the very least, I'll share my experience with having the tape made. If the price comes back as being quite reasonable though, I don't think shipping will be an issue. A first class package under 8 ounces can ship from US to Germany for around $14. Those flat rate boxes are way overpriced.

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How would you want to repair a logic analyzer without an logic analyzer? :D

 

I think 1 Meter is ok, a bit longer may be better but if 1 meter is the max. length its ok. How do you do the layout? I found DraftCad, do you have an alternative?

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Hello. Thinking about building an arduino-based simpit. Just a question - is it more advantageous to have the Mega or the Due? I'm not really sure whether speed will matter in this case, or whether it is better to have the extra analog ports of the mega.

(And if it matters, I do already have some experience in coding, electronics, and light carpentry. Not necessarily to the point of the stuff already here, but some)

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Posted (edited)

On 5/26/2017 at 0:47 PM, Pvt. KASA said:

How would you want to repair a logic analyzer without an logic analyzer? :D

I think 1 Meter is ok, a bit longer may be better but if 1 meter is the max. length its ok. How do you do the layout? I found DraftCad, do you have an alternative?

It's been a long time since I looked at it... Might just be a power supply issue. It uses ECL chips (Emitter Coupled Logic) rather than the typical TTL or CMOS versions, as ECL comprised some of the fastest chip speeds until CMOS overtook it int he early 1990s. Problem is, it's kinda power hungry, so it has a big beefy 400 or 500 watt power supply. If it's just a power issue, then it's an easy fix... I just never got around to bothering to look. I THINK it's A Gould Biomation K100-D... But I'd have to runout to my storage unit to see. I think it had 16 lower speed 20 MHz probe channels, and 16 active probe channels, good for up to 100 MHz (though it only has a memory of 1024 words). Looking at the manuals online, I'm seeing dates of 1980 and 1981... Definitely not bad speeds for that era! These days, that's nothing. Basic entry level stuff. The main issue is the SIZE! It's HUGE! 19.5 kg/43 pounds, 22x45x55 cm (9x18x19 inches). It's a bench beast!

I also have the service manual for it... So I probably COULD actually pinpoint a fault in the unit if I really wanted to. I just haven't had the desire to go digging.

As for the tape length, 1 meter is the limit for my specific tape meter, because it's in a continuous loop. A reel to reel style tape meter could be made longer than a meter, if desired. It would only require a different scale. As for format... I don't know yet. The shop knows this is a one off, low priority job that'll only net a small fraction of a fee, compared to large batch orders. They've been too busy lately. I asked what format i could submit a file in though, so if it's something I can work in, I might do the layout myself... Honestly, I was probably gonna work in a large high res image format, if they can accept that. Unless they say otherwise, that's all I can think of. As for the design, it's a bit inconvenient, as it requires each printing to cure, as the tape has to be rotated around to expose the next blank section, while the previously printed section faces down then. My particular design will take three separate printings, so it's a really unusual print job.

Edited by richfiles

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On 2017-5-27 at 10:37 AM, qzgy said:

Just a question - is it more advantageous to have the Mega or the Due? I'm not really sure whether speed will matter in this case, or whether it is better to have the extra analog ports of the mega.

One factor where the extra speed/power can come in handy is dealing with floating point numbers. Neither of those processors have an FPU, but the slower chip can really start to struggle if you're trying to do a lot with peripheral comms and shunting floats around. The biggest issue I've seen in the KSPSerialIO thread is with serial comms falling out of sync because the Arduino code is too busy dealing with floating point math to keep the serial buffer drained. 

Not an impossible situation to deal with (most of the time, just hacking the Arduino serial lib to give it a buffer to match the KSPSerialIO packet size is enough). But something to consider. 

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Depending on what you want to do you can handle a lot of calculations with simple fixed point arithmetics. Convert from float to integer, shift left ten bits (equivalent to multiplying with 1024) and you get approximately four decimals to work with, do your arithmetics, convert to a float and divide by 1024 and you get your result. You have to be aware of precision loss when multiplying and dividing to know how many decimals are actually valid in the end, but it makes a big difference in speed.

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