TG68 - The Open Source Minimig CPU into the FPGA

[HenryCase]

freqmax wrote:
Regarding ethernet. What you will need is a PHY.

It looks like the microcontroller MiniMorph is proposing we use already handles the physical layer of the ethernet connection for us.

@Minimorph
First of all, thank you for taking on this project, the possibilities unlocked using an improved bootloader and ethernet+USB connections are great.

I would like to ask you a few questions.

1. As the LM3S6965 chip and FPGA would both be reprogrammable through the JTAG port, could we configure the LM3S6965 to act as a co-processor at runtime? Not sure why we would do this, just wanted to know if it would be possible.

2. LM3S6965 adds USB and Ethernet connectors to the Minimig. How easily can these be used for outgoing comms if Minimig code was amended to think they are serial port connectors?

3. Does the microSD slot support SDHC cards?

4. Price issue. So that I had some understanding of the added cost, I went onto Digikey's website. For the Microcontroller itself, we're talking around $13.10 USD:
Link
The evaluation board is around $69.00 USD:
Link
Other than the LCD screen and speaker (neither of which I see as essential, especially as the new bootloader would handle selecting the cores), would we lose any features by incorporating the microcontroller, microSD slot, ethernet port, JTAG port and USB port directly into the Minimig PCB design?

5. Last question relates to the bootloader. It seems to me that you are looking to replace the PIC with the LM3S6965 rather than having both devices on the board. I noticed that you plan on using ZIP files to hold the FPGA core data. Would the PIC chip used in Minimig 1.1 be powerful enough to do the unzipping? Just want to make sure Minimig 1.1 owners get access to the new cores.

[MiniMorph]

To answer your questions.

1) Yes, sure the Luminary chip could be used a a co-processor.  I was really planning on making the Luminary chip emulate things like Tape Drives, Floppys & Hard Drives and then also to hook the legacy ports to Ethernet. I think these tasks are best handled in software and as the boot loader would provide it capabilities to all cores it. The sort of thing that would be possible is downloading a program directly into your core from the internet.

2) The Luminary chip has no USB, that is provided by an ftdp chip that acts as a JTAG Interface and USB to serial port converter at the same time. It should be pretty easy to get Ethernet communications through the Luminary chip from the FPGA core. Simpler than emulating hard disks and the like. I anticipate using UDP, TCP/IP, TFTP and FTP communications. HTTP stuff is also possible but I do not see what you could do with that.

3) I am no expert of SDHC, if you can talk to an SDHC card using SPI then I guess it can be made to work. I will do more digging. I would think 2GB is quite a lot of software for an Amiga Classic .

4) I think $13 is pretty good for what it does. The evaluation board is also very good value. i just wish mine would turn up !! The tool chain is open source and free to download which is nice too.

The actual part I would use on a PCB would be the LM3S6918 Micro controller. I also plan to make use of the A/D converters and Real Time clock capability.

[HenryCase]

Thanks for the reply MiniMorph, I'm sure I'll have more questions later as your project is an exciting development. Make sure you keep us posted with your progress.

[freqmax]

13 USD for another chip is a bit. Esp considering the FPGA is 25 USD..
I don't propose 1 Gbps for Minimig. But it might be easier to source those chips etc..
Because 10M ethernet can't be accomplished without external hw, and 10/100M chips are the slowest ones that exist. 10/100M is the best choice.

[AJCopland]

freqmax wrote:
13 USD for another chip is a bit. Esp considering the FPGA is 25 USD..

Its not that much if it's replacing the PIC that costs £5.04 with a part that costs £6.80 (prices from Digikey uk).

Ok that does selectively ignore any additional components required for ethernet like the connection block etc.

Andy

[AJCopland]

downix wrote:
One thing I was pondering was in rolling this into a spare FPGA I have, and pairing it next to an original 60000, to duplicate instructions and see what differences there are.  Just need to find a minimalistic motherboard design for the 68k, like the old Altair, so I can directly manipulate them.

Didn't see this before.

Have you tried doing this?

Andy

[downix]

AJCopland wrote:

downix wrote:
One thing I was pondering was in rolling this into a spare FPGA I have, and pairing it next to an original 60000, to duplicate instructions and see what differences there are.  Just need to find a minimalistic motherboard design for the 68k, like the old Altair, so I can directly manipulate them.

Didn't see this before.

Have you tried doing this?

Andy

Not yet, I cannot find any good documentation on how the front panel was programmed, so I'm having to recreate it by hand.  

[freqmax]

What do you mean by frontpanel..?
Can't you use the FPGA to manipulate the m68k ..?

[downix]

freqmax wrote:
What do you mean by frontpanel..?
Can't you use the FPGA to manipulate the m68k ..?

And manipulate it, how, without a keyboard, mouse, or other method of input?

I am trying to mimick the "front-panel" input from the first PC, the Altair:

[MiniMorph]

Cheers.

freqmax wrote:
13 USD for another chip is a bit. Esp considering the FPGA is 25 USD..
I don't propose 1 Gbps for Minimig. But it might be easier to source those chips etc..
Because 10M ethernet can't be accomplished without external hw, and 10/100M chips are the slowest ones that exist. 10/100M is the best choice.

13 USD is just the list price I would hope to get it cheaper than that. It is not that much money to add 10/100 Ethernet to the board along with all the rest it can do, like real time clock and A/D's.

If there were a Mini Morph 2 then I am guessing that the 68000 would be run in the FPGA itself and thus a more expensive than 25 USD FPGA would be required.

I am glad you approve of 10/100 Ethernet, I think it would be fine too, and with a 50MHz Cortex M3 processor to pick up the Ethernet it should fly !

I will continue with development of my Minimorph Bootloader. I let people know when I have it working in this forum if there is interest. In the meantime I will post my progress on my own site as mentioned above !

P.S. does anybody know where to buy Altera DE1 boards in the UK/ Europe ?

[Colin_Camper]

I just bought a DE2 from Terasic.

They quoted 2 days shipping to the U.K. and they even take Paypal!  :-)

[MiniMorph]

I have had a lot of trouble with parcelforce charging a nearly  £20 handling fee for stuff from outside of the EC. I now try and order from Europe.

[denli]

@downix

Could you please scale down your pic.
We can't read the forum properly any more.

[A6000]

All the projects using front panels that I have seen, used switches and leds connected to the address, data and control lines, there is nothing to program (in the front panel).

[freqmax]

Some Administrator, plz reisize or disable this huge picture..

@downix:
Ofcourse you can manipulate the m68k, simple connect to the jtag interface of fpga. Or even use any existing RS232. Or a planned 10/100M ethernet.

[HenryCase]

I frequently use URLs that are too long in my posts, but I do know how to easily resize them. If downix or any other forum member is looking for an easy way to resize pictures they find online, check out this method:

1. Copy URL of image (right click->copy image location in Firefox).
2. Go to http://www.shrinkpictures.com/
3. On Resize Images form, click browse. In file open dialog, paste image URL, click on Open button.
4. Select resizing options, then click on Resize button.
5. Once image resized, you will have an option to host image at www.4freeimagehost.com. Click on the link. Use hosted image in forum post.

Here's the link to the resized Altair 8800 image I made:
http://www.4freeimagehost.com/show.php?i=PUSHdfc6b739ddc9.jpg
It has lost some of the cool detailing visible in the full size picture due to its smaller size (25% of original), which is a shame.

Hope that this post is useful.