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Message Removed
modified 27-May-22 16:57pm.
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Message Removed
modified 27-May-22 16:57pm.
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I needed a second USB port on my little music widget, so I bought a USB-A connector in the buff - just the 4 pins, no controller chip.
The plan is to bit-bang the USB over this by manipulating the data pins directly.
*cracks knuckles*
The issue is timing. I have to cycle count, which means asm NOPs are in play. In order to make this work i have to do a special malloc which gives you executable memory back, and then fill it with machine opcodes to make it do the operations I want.
I also have to fudge GCC with attributes to get it to generate the right bytecode everywhere else.
I haven't written anything like this since the last time I created self-modifying code.
I don't even remember when that last was.
This is black magic, friends. There be dragons.
And all because MIDI over USB doesn't quite work the way it should.
I still can't decide whether I enjoy this kind of thing or loathe it.
It's like tuna fish sandwiches that way. I think I like it, until I eat a few bites, and then I wonder why I made it. 
To err is human. Fortune favors the monsters.
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I hope you have a good scope... if not.... well.... good luck.
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I have one of the best logic analyzers money can by. Scopes are better for analog stuff.
To err is human. Fortune favors the monsters.
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honey the codewitch wrote: I have one of the best logic analyzers money can by.
Said the Ferengi when he tried to sell something to a Vulcan. 
That's a very high praise. These things can go up to price ranges for which normal people buy real estate.
I have lived with several Zen masters - all of them were cats.
His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
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CodeWraith wrote: These things can go up to price ranges for which normal people buy real estate.
Okay, apparently I should ... rephrase that.
I have a salae 8 channel. The last I checked they cost $1000+, so not real estate territory, but significant.
To err is human. Fortune favors the monsters.
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Hust did a quick search and found one for just 24000 as the second result. The really expensive ones can easily reach six figures, but these usually don't pop up as consumer products. The same for oscilloscopes. These devices usually don't make much sense to have at home. And that's also one reason why I use such an old processor for my tinkering. I don't get poor and still can have all the devices I want. It does not even make a dent into my bank account.
I have lived with several Zen masters - all of them were cats.
His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
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Just started using Saleae this year - great products.
On Tuesday - my Logic 8 went completely dark - no recognition on USB plug in, no life whatsoever 
Contacted Saleae - explained the problem. Got an e-mail saying a replacement had shipped.
Got it Thursday - no charge, no need to return the dead unit. Took me half the day to get my jaw off the floor.
Highly recommended.
If you can't laugh at yourself - ask me and I will do it for you.
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I absolutely love them. Instant tech support no matter the time. They put you in touch with their engineers, who actually go out of their way to help you and answer questions.
It's so refreshing. I've never had service like this for anything before.
To err is human. Fortune favors the monsters.
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As long as you trust the generated signal is within the published timings, and not just what the logic analyzer accepts.
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If you mix the tuna (packed in water, not oil) with Miracle Whip and add just a tiny bit of pickle relish -- served on multi grain bread.... with Vinegar & Sea Salt potato chips (crisps to some?) on the side. Mmmm
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Craig Robbins wrote: Miracle Whip
GET BEHIND ME SATAN!
I just threw up a little in my mouth.
To err is human. Fortune favors the monsters.
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And where are you if given the choice between an IPA or a Guinness Draught to enjoy with your Tuna Sandwich and chips? (I'm firmly in the Guinness camp.)
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I don't drink, so .. neither?
To err is human. Fortune favors the monsters.
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honey the codewitch wrote: This is black magic, friends. There be dragons.
You can try to scare the ignorant fools who may or may not exist here, but not me. I'm chaotic evil too.
honey the codewitch wrote: I also have to fudge GCC with attributes to get it to generate the right bytecode everywhere else.
honey the codewitch wrote: I haven't written anything like this since the last time I created self-modifying code.
Also known as one sinister hack upon another.
honey the codewitch wrote: I still can't decide whether I enjoy this kind of thing or loathe it.
Then you are not chaotic evil.
honey the codewitch wrote: It's like tuna fish sandwiches that way. I think I like it, until I eat a few bites, and then I wonder why I made it.
That only proves that you are not strong enough to withstand the mind control of a minor deity. Probably the one that already stands ready whean you open the can.
I have lived with several Zen masters - all of them were cats.
His last invention was an evil Lasagna. It didn't kill anyone, and it actually tasted pretty good.
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More years ago than I like to remember, I was working on the programming for an industrial laser (1KW CO2). This was supposed to run the laser at the command of a CNC, but the documentation was not all that could have been desired.
We were reduced to similar expedients to ensure that we got good communication between the CNC and out hardware. Having an out-of-control 1KW laser running loose is no joke!
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Did that one myself. I wrote the control software for a machine with three visible light red, green, and blue lasers, along with an IR laser. The red, green, and blue lasers were pretty safe, but the IR was not. There were interlocks on all of the doors that cut laser power if the doors were opened.
Also, as protection against the soft schmuck making a mistake, the s/w had to toggle a bit on a port once a second to maintain power to the entire machine.
Software Zen: delete this;
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Waaayyyy back in the time, I had to bit bang a 1200 baud serial port while driving the pins and motors on a slip printer.
Managed this on a 6801/3/5 by using state machines stepped by a timer, or timers, interrupt(s).
Very accurate and easy to tweak.
Good luck.
"Time flies like an arrow. Fruit flies like a banana."
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I wish i could use a timer like that, but the timing is too tight for this. It's gotta be clock cycle accurate.
You run into a similar problem on the old Nintendo since it didn't have a frame buffer and the CPU, while faster than the scan gun, still wasn't that fast.
So you had to cycle count to plot, following the scan gun top to bottom, left to right until you reached the end.
On a faster system you could use a timer for that.
To err is human. Fortune favors the monsters.
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honey the codewitch wrote: It's gotta be clock cycle accurate
I did that on a PIC microcontroller once. We needed a one-second signal and a 15-minute signal, and the only timing reference was the CPU clock. Lots of pre-calculated values, NOP's and such, all in a single page of code. Lots of fun  .
Software Zen: delete this;
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This is kind of like that except I have to dynamically generate the code. It's because the line changes on a USB interface are so tightly timed, and just ... i don't know if there's another way to do it.
To err is human. Fortune favors the monsters.
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My approach worked only because I knew the CPU clock frequency accurately and the project was a one-off.
Software Zen: delete this;
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I used to play around with this in my deep dark past. Is indeed a dark art, and can be deeply pleasing.... 😉
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honey the codewitch wrote: I still can't decide whether I enjoy this kind of thing or loathe it
I predict you will enjoy creating it and getting it to work.
I also predict you will loathe it the first time it goes sproing.
Software Zen: delete this;
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