Raspberry PI

[nyteschayde]

What would be the fastest I/O for data between an Amiga and the PI? It seems like it's still the unanswered question I come to when I consider any microcontroller or mini-computer such as the PI.

I'd like to leverage the power of the PI in conjunction with an old Amiga somehow? Anybody have any ideas?

Would it be like a PCMCIA<->GPIO adapter or perhaps a trapdoor edge connector <-> GPIO? I've also considered the clock port but I haven't been impressed with what I've seen with the Subway USB speeds.

Let's brain storm!

When the boards were going to be self produced, only the first 10,000 would have the GPIO headers... Now RS and farnell are manufacturing I don't know... I'm hoping my Pi will have the header as I want to play with it

[nyteschayde]

Make sure you have enough power. Seems that is the most common issue I've heard with the PI. Mine still hasn't arrived so I can't say from experience though.

mmmh...my raspberry arrived, installed the Linux image from website and the USB mouse is not recognised...argh!

[nyteschayde]

You could try running the mouse through a powered hub and see if that is the issue after all.

Got myself one of these:

http://www.ebay.co.uk/itm/Micro-USB-Power-Supply-For-Raspberry-Pi-Computer?item=330730087675&cmd=ViewItem&_trksid=p5197.m7&_trkparms=algo%3DLVI%26itu%3DUCI%26otn%3D5%26po%3DLVI%26ps%3D63%26clkid%3D8751643704345737842#ht_1221wt_1397

And the USB mouse does not work. Tried another one and still the same. Bah!

[nyteschayde]

Not necessarily but I've heard everything from the leads, the contacts, the sometimes even the day of the week (jk) dropping a tenth of a volt and causing things to not function.

If it works via the powered USB then it means that the psu is pants?

[nyteschayde]

I take it the powered hub worked?

I AM really impressed...worth the money!

[nyteschayde]

That or using the PI like a bridge board or how about as a video card? All these things have crossed my mind. I'm a software dev and love to sit down with a good hardware dev for a day or two to know more about things like PICs and working with and wiring up a GPIO.

Slightly O/T.

Can the PI be rigged as an accelerator?

What's to stop somebody wiring up the accelerator port in an A1200 to the Pi via USB  (or faster bus - obviously may need some sort of breadboard inbetween) and passing the instructions to an ARM 68000 series emulator such as http://notaz.gp2x.de/cyclone.php (this emulator is 68000 only)?

Obviously FPGAs are better for the purpose but technically I can't see too much trouble apart from:

• Conversion between the trapdoor connector to USB serial will likely need custom PIC work.
• Custom software glue to pass the USB instructions ARM side to the relevant emulator API and return results.
• Emulator may need modification for access to the Amiga chipset and chip ram, as opposed to ARM ram,  via USB

 It may be a tad slow... and now I've written this post probably complicated.

[nyteschayde]

Before I ordered the PI, I was all about trying to figure out a way to arduino-up my Amiga. I'd still be interested. It's so frustrating for me because I understand just enough to not be able to know the right direction about how to best use the hardware.

Also, Amigas are not a dime a dozen so the thought of damaging one in testing also frightens me. So, I understand that most modern electronics use 3.3 volts and older stuff like the Amiga uses 5 volts. How do you do "level shifting"?

Also I asked earlier about the fastest interface area. I know the mediator, for example, has a pass-thru for the cpu 150 pin slot adapter for the A1200. Perhaps something like that would provide the best solution, but how do you make subsequent attachments work?

I've also read that you may need a PIC or something (again, what is a PIC) to create/call/provide (?!) interrupts at the 14MHz cycle in order to make the rest of the hardware happy if you wish to provide some sort of accelerator.

Do you need to connect to all 150 pins? What is the minimum needed if your microcontroller/microcomputer has only in the range of 25-35 GPIO pins?

I would love to get into an IRC chatroom with anybody capable and patient enough to explain this stuff to me; or better yet, in person in you're in San Jose, CA.

I've been thinking of using a microcontroller board as some kind of super I/O board for a classic Amiga. There are a lot of chips out there that do cool stuff like mp3 decoding, radio reciever, networking and usb hosting. Seems like a microcontroller could host these - via SPI. and communicate with the Amiga via a parallel interface.
One thing to consider, I'm almost sure the PI uses 3.3v logic. You'd need some level shifting to connect to the Amiga.

[nyteschayde]

If you get one of the other boards, let us know how it goes!

Got my email from rs today but am a bit reluctant to order after seeing the via board and a few of the other arm boards.

[nyteschayde]

I don't know about speed. What I had in mind was making a card for the Zorro bus (but too lazy to do autoconfig) that implemented a 16 bit parallel port.

What is wrong with the physical parallel port on the backside of the Amiga's? Are they too slow? Were you planning on something else so that it could be handled from the inside of the machine?

[nyteschayde]

Nothing wrong with the built in port... except that it's only 8 bits wide.... and I'd prefer to leave it for the printer. BTW. "planning" is too strong a word. ;-) It's just some ideas I've been mulling around.

Interesting, so would you say that each GPIO pin is roughly a bit given it's states are likely high or low. Therefore if you had 8 pins you could spit out roughly a byte at a time? Is that how this works. Give some signal to read, the software reads the state of pins 0-7 and assigns their values to bits 0-7 respectively and then either waits for the next read now signal or otherwise signals the device that it's ready for the next byte's worth of bit/GPIO pin values?

Is this roughly how data transfer between them would take place? Or could you do something like set the voltage on the GPIO pin to be a value between 0.0v and 0.256v and read the voltage as a byte value? Not sure how precise voltage can be set and read.

What are the maximum throughput values if it's used like this? Sorry if this is way OT, but I'm just pondering in "out loud" in these POSTs now.