FPGA Board suggestion

[rstofer]

In a discussion about microcoding last week, I got interested in the LC3 RISC processor from Patt & Patel.

I have the basic instructions running and I just stumbled across an assembler written in Python (although the authors provide tools, they are best implemented on Linux and I don't have that on my new machine.  So...

I'm here to tell you that no matter how many 7 segment digits, LEDs, buttons and switches you have on the board, it's not enough.  I wind up displaying all kinds of internal signals while trying to find my errors.

I like the "stamp" format like the boards from ZTEX

https://www.ztex.de/usb-fpga-2/usb-fpga-2.01.e.html

but only if I have the debug board to go along with it

https://www.ztex.de/usb-fpga-2/debug.e.html

I'm using a Nexys2_DDR board for LC3 because it has a lot of gadgets.  They come in quite handy.  I'm not really very interested in boards without features.

[legacy]

I like the "stamp" format like the boards from ZTEX like
but only if I have the debug board to go along with it

That is the board I was talking about some posts ago!
Bought one, and I am not interested in the companion board because the 2.04 board offers

• a fast usb link, I use it as "scope", and "upload/download" link to/from the sdram/bram
• a Cypress MPU, I use it as "advanced debug processor(1)"
• SDRAM, I use it as data and code memory for the softcore, but I have also reserved slices for the "scope"

I don't need I/O in this case, except I/O for an external asynchronous nv-ram
I am going to make a backplane PCB like the one I designed for the Papilo/Pro

I mean something easy like this:




(1) I have designed a debug processor in vhdl, but, in order to consume small resources, it ended to be like jtag, thus an external MPU running a protocol GDB-like is better.

[simmconn]

I'm not sure if they did it on purpose or what, but some small changes at the time of design could have made the low-cost FPGA boards more attractive for people who develop products using low cost FPGAs:

On Basis 3, they could have wired the unused PIC ports to the unused FPGA I/O pins, so a 'maker' could develop FPGA applications with USB connection. They came to the senses on the CMOD S6 but then decided to hide away the entire USB part from the schematics on the CMOD A7.

On the CMOD A7, they could have routed differential pairs to the PMOD to facilitate LVDS applications like on the other boards (so-called High Speed PMOD), yet they did not.

[newbrain]

While looking for a board with good options I came across the shop linked below on Aliexpress. It seems to have a nice selection and variety of boards, while also having very decent prices. I have not received my board yet, but have been communicating with them for a while now about a board that was mentioned but not stocked and that left a good impression. Language is obviously a barrier, but the responses are swift and effective. The documentation of the board has been sent my way and seems to be adequate, with the various devices and pin-outs described. It seems to be enough to make good use of the board. A guide on how to test the board and various code examples are also included. If there is any interest, I will report back when I receive the board.

Please note that I am in no way affiliated.

https://www.aliexpress.com/store/620372

Thanks Mr. Scram!
I was looking for some cheapish, but not too barebone FPGA board, so I bit the bullet and invested 400SEK (~50$, now it's 460SEK) in this EP4CE15 FPGA+base boards.

The FPGA is neither recent, nor large (15K LE) but as a first step -not counting PSoC!- I think it will be more than enough to get a taste.

The seller answered my request for info in minutes (never happened to me on AE!) and sent the links to the documentation, which looks quite OK.
As Mr. Scram says, plenty of examples, FPGA and base board schematics, even IC datasheets and "English" user manuals, not exactly Shakespearian prose, but who am I to judge...

We'll see when (if?) I receive it , it's the highest sum I've ever spent on AliExpress let's hope for the best.
Now let's go and read all the Verilog vs. VHDL thread...

[Mr. Scram]

Thanks Mr. Scram!
I was looking for some cheapish, but not too barebone FPGA board, so I bit the bullet and invested 400SEK (~50$, now it's 460SEK) in this EP4CE15 FPGA+base boards.

The FPGA is neither recent, nor large (15K LE) but as a first step -not counting PSoC!- I think it will be more than enough to get a taste.

The seller answered my request for info in minutes (never happened to me on AE!) and sent the links to the documentation, which looks quite OK.
As Mr. Scram says, plenty of examples, FPGA and base board schematics, even IC datasheets and "English" user manuals, not exactly Shakespearian prose, but who am I to judge...

We'll see when (if?) I receive it , it's the highest sum I've ever spent on AliExpress let's hope for the best.
Now let's go and read all the Verilog vs. VHDL thread...

You're welcome, I'm glad I could be of help. The seller is unusually responsive indeed, and a pleasure to deal with. The English is not perfect by a long shot, but functional enough to get the job done.

Can I ask you about the PSoC family you worked with? I'm having trouble estimating how much or little custom logic you can actually fit inside one of these microcontrollers. That makes it hard for me to judge whether an FPGA with a microcontroller embedded or these PSoC chips with logic added will be more suitable for my purposes.

[newbrain]

Can I ask you about the PSoC family you worked with? I'm having trouble estimating how much or little custom logic you can actually fit inside one of these microcontrollers. That makes it hard for me to judge whether an FPGA with a microcontroller embedded or these PSoC chips with logic added will be more suitable for my purposes.

"Worked" == having fun as a hobbyist!
So take what I say with a large pinch of salt.
I'd have liked to give some actual example, but I'm far from my machine (about 2500km, and I managed to shut down my VPN server VM, so I cannot reach my git repos... ).

I have only used PSoC 5LP, which has 24 UDBs.
UDBs bear some resemblance to the usual FPGA LEs, but the addition of the so called "Datapath" make them more powerful.
Each UDB contains two PLD 12C4 structure, with their macrocells, and a datapath.
The total product terms for a PSoC 5 is 384 (8 per PLD).

In what I have done, I've never hit the limits, closest I got was for this frequency meter due mostly to the long chain of dividers by ten:


Of course, the complexity is limited, but to see someone stretching the capabilities to the limit, see this thread.