I/O Cartridge (Show and Tell)

A place to discuss everything Dragon related that doesn't fall into the other categories.
Rink
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I/O Cartridge (Show and Tell)

Post by Rink »

Work on a couple of projects hit a stumbling block when my breakout cartridge + breadboard combo proved a little unreliable. So I transplanted some of the logic being tested onto a new board and recently received the PCBs from China. Surprisingly, they work. :D

Image

This is a latched input/output cartridge that offers 8 digital outputs (selectable between 5v and 3v3 operation) and 8 digital inputs. Writing/POKEing a byte to 0xFF40-0xFF5F causes the latches to mirror that value on the output headers until you send a new value or the Dragon is turned off. Reading/PEEKing 0xFF40-0xFF5F latches the state of the digital inputs and gives you a byte with each bit representing a pin. Though to be honest, the main reason for latching input was just to get a cheap, easy way of tri-stating the data lines.

Wish I'd found different headers though, the ones I've got require a fair bit of force to insert a wire... I suppose the fact that they hold the wire in pretty securely could be considered handy though.

And damn those resistors are ugly. :(

Anyway, just thought I'd post since I don't know anyone else who'd be remotely interested in any of this.
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Rolo
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Re: I/O Cartridge (Show and Tell)

Post by Rolo »

Nice board Rink!
Seems like nobody is using the Dragon as a controller? Not much discussion going on, hmm.
Anyway, good idea for controlling toys like Fischertechnik, LEGO or Märklin.
Or how about an "eight channel sound card"? Maybe STEREO: 4 left, 4 right. (You could start a synthesizer demo scene on the Dragon :idea: )

What's wrong with the resistors? Use a resistor array, if you can't stand them. :)

Maybe you could take headers, with screws, like this one:
CIMG4909.JPG
CIMG4909.JPG (98.6 KiB) Viewed 2869 times
But those have a 200 mil spacing, so you'll probably have to change your board design a bit.
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tormod
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Re: I/O Cartridge (Show and Tell)

Post by tormod »

I'd suggest to use male headers on the board. Then you can use wide, female headers for more permanent setups, or just Dupont wires for prototyping. Dupont wires and headers are nearly for free on eBay. Rolo's headers with screws are perfect on the front-end, where stuff/sensors/relays etc are connected with long wires, but I guess that would be on a second board.
Rink
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Re: I/O Cartridge (Show and Tell)

Post by Rink »

Rolo wrote:Nice board Rink!
Cheers fella.
Seems like nobody is using the Dragon as a controller? Not much discussion going on, hmm.
Yeah, I suspect there are other easier ways to control stuff these days. :D But I was a robot guy or something going to a maker fair, what better way to demonstrate my coolness than to control the project with a classic British 8-bit micro!!!

Lol. I really just use the thing for bit-banging SPI etc. mind. Don't tend to do much with sensors and motors etc. I can see MIDI being doable and possibly a fun experiment. :D

Interesting advice on the headers though (you too Tormod), I didn't put a great deal of through into that bit. I guess it was the Arduino influence which made me reach for a female header strip without thinking through the other options.
Rink
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Re: I/O Cartridge (Show and Tell)

Post by Rink »

Oh yeah - the resistors. I probably should have used a resistor array but the board kind of came as a spin-off from a different project/experiment which doesn't need all of the 8 ins/outs connected - so in the case of the original, I only needed a few resistors. Rather than put much effort it, I just added more of them when creating this board.

Must learn to use surface-mounted parts though - would tidy things up a lot.
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tormod
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Re: I/O Cartridge (Show and Tell)

Post by tormod »

I just read the Coco wikipedia article, and I think this quote is appropriate here :)
The precise timing loops made the CoCo useful for laboratory purposes. Since it has no operating system servicing interrupts, it can do precisely timed read-modify write operations for scientific instrumentation, at a speed that cannot be matched by even the newest Windows computers without disabling the Windows operating system.
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Rolo
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Re: I/O Cartridge (Show and Tell)

Post by Rolo »

Ha. ha, that's great. We are back! The next high speed train is going to be controlled by a bunch of Dragons :D
Rink
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Re: I/O Cartridge (Show and Tell)

Post by Rink »

Lol. I liked that.
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Rolo
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Re: I/O Cartridge (Show and Tell)

Post by Rolo »

@Rink: By the way, do you have a PCB left? I'd like to have one. No, I don't have are real job for a "Dragon controller", but I simply like to play around with it.
Rink
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Re: I/O Cartridge (Show and Tell)

Post by Rink »

Rolo wrote:@Rink: By the way, do you have a PCB left? I'd like to have one. No, I don't have are real job for a "Dragon controller", but I simply like to play around with it.
Yup. If you want me to assemble one for you I can probably do that. If you just want the PCB itself then I can certainly send one your way.

Shoot me a PM.

Edit: Oh. There doesn't seem to be a private messaging system on the forum. Um... One sec...
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