FYI - FPGA Development Board Bargain

(Stephen Davies) #1

If you’re interested in FPGA development, Digilent are running out a Spartan 6 board at half price.

The catch? Xilinx have started release of the Spartan 7, so not yet obsolete but on the way.

Having said that, the board has loads of stuff mounted, breadboard, keypad, large and small LCDs, 6 x 7Seg digits and more.


(Chris Small) #2

nice! =)

(Derryn Harvie) #3

I’m going to be getting one of the newer Lattice MachOX3 boards to muck around with in combination with the ESP32.

I’ve used the earlier versions in projects and their quite nice. Definitely not the anything like the scale of the FPGA Steve linked in, but they’ve been more than enough for the things I’ve been doing with them (i.e. not building processors in the FPGA fabric.)

One of the best bits about them from my perspective is they’re cheap and simple enough to build the whole board into a one off project and not have to deal with fanning out a BGA.

(Chris Small) #4

Wow! Those really are cheap!

(Stephen Davies) #5

The MachOX3 data sheet is an interesting read. Haven’t compared FPGA’s between vendors before, it’s interesting to see what features they include.

The Mach family seem comparable with the bottom end of the Xilinx Spartan 3 family, both are LUT4. The on chip flash is nice, as is the i2c peripheral. Not so sure about the spi port, pretty easy to create one of these from fabric.

Block memories are comparable between the two. A major difference is dedicated multiplier hardware, absent in the Mach chip.

I think you may be underselling the board Derryn, you can do a fair bit with 6900 LUTS. A soft core processor is certainly doable. My Apple2FPGA project uses 15% of the LUTS (~2400) in a Xilinx XC3S1000. That includes the 6502 plus video controller. There would probably be enough memory in the Mach to simulate the 8k ROMs plus 16k of RAM. The S1000 can do 2x8k ROM plus 48k RAM.

(Derryn Harvie) #6

You’re quite right Stephen. The previous machXO board I had (the original series) was < 1/3rd the number of LUTs and was firmly marketed as glue for interfaces, not as in glue logic but rather you could use them to bridge weird and wonderful interfaces.

What I also find interesting in this newer series is one can get a 36pin 1300k LUT FPGA for ~ $3 in low qty. WIth on-board flash that’s pretty much the total cost. Albeit the 0.4mm pitch BGA doesn’t fill me with joy!

(Stephen Davies) #7

I see the tooling is free. How does it rate? The new Xilinx tooling gives great insight into what/where and how, being able to locate logic placement within the die really helps with the learning curve, but can be very slow.

What does it need programmer wise?

(Derryn Harvie) #8

I haven’t used their tool chain in anger for a few years now, so I’m reluctant to comment too much. But back then it didn’t seem as advanced as the Xilinx or Altera offerings. You probably saw it, but the tool chain is only free for the lower end product such as the machxo series, not some of their other larger FPGAs (this is much the same as the other vendors.)

Programming is easy, the machxo breakout boards have a FTDI chip that is configured as a JTAG programmer on board. So you just plug the board into USB and away you go. Otherwise I guess they probably sell an independant JTAG programmer but I haven’t looked.

(Stephen Davies) #9

Hi Derryn,
FYI I spotted this today:

(Chris Small) #10

Cool! How much do those go for, Stephen? What synthesis tools are required?

(Eyal Lebedinsky) #11

Click the link to Tindie to see the price. Note that there is also a larger, slightly dearer A2. There is a link to the User Guide which answers the software question and indicates that you need a JTAG programmer too.

I did not use these myself.

(Luke Valenty) #12

FYI I’m running a 10% discount on these because I’m out of town and shipping is delayed until August 15th. Once I’m back in town the discount code won’t work anymore so get them now if you’re interested :slight_smile: