Following the mega useful suggestion from aventuri about the existence of this board I bought one because I couldn't find any other way to get hold of a Lattice UP5k FPGA chip in 48 pin QFN.

 

This is an interesting FPGA in that it has 5k LUTs, the usual block RAM (15kbytes), 4 single port RAMs totaling 128kbytes and 8 16 bit wide multipliers, all this in a 48 pin prototype friendly QFN package and quite cheap - if only anyone had them in stock.

 

The UPduino board has A UP5k, an absurdly large (32Mbit) flash for program storage, a three colour LED, power regulators and not much else. It is very cheap at $7.99.

 

The owner of Gnarly grey worked for Lattice for several years and thye are promoting the board on their website.

 

My board came very quickly from the US to here in the UK, no fancy packaging, just a poly (anti static) bag in a standard envelope.

 

I got it going today which took way longer than it should have done you can program the FLASH memory using standard Lattice software with an FTDI breakout board or cable I didn't have a board but I did have a  C232HD-DDHSP-0C232HD-DDHSP-0 cable(Farnell 2352017 To cut a long story short the cable won't work unless you reduce its length drastically I cut mine down to about 10cm long This is because neither the FTDI chip in the cable or the FLASH chip on the FPGA board expect to drive cables when the data changes on the output of the FLASH chip it cross couples into the clock signal due to the cable capacitance and the resulting clock glitch breaks the communications Crazily it took a 1GHz scope to debug the comms the FLASH chip is fast and the glitches are short

 

The hardware design of the board is truly dreadful - OK it was cheap but it is kind of amazing bearing in mind the makers' connections with Lattice. It breaks several of Lattice's design rules for this part.

 

There is almost no power supply decoupling on the board.

There is no ground plane and the ground is a spidery thin track weaving about the board.

Lattice recommend a filter to the FPGA PLL power pin - the UPduino has the series 100R resistor but does not have a capacitor on the FPGA side of the resistor to ground.

 

 

There is no precision oscillator on the board - the UP5k has its own rubbish 48MHz (+/- 10% for 0-85C)) oscillator on chip but this isn't good enough for a great many things. It's worth putting the oscillator on board so the fast clock doesn't have to have long wires.

 

I'll add to this blog if I do much more with the UPduino - it's tempting just to remove the FPGA and put it on my own board.

 

The supplied example files are pretty gruesome, possibly below even Lattice's pretty low standard for example code. The LED blink example is quite short but has not one single comment !

There is a Raspberry Pi IO expander example on GG's website - the key file in that is spi_gpio.v - oddly embellished with Lattice copyright stuff and dated 2010 - 310 lines of code - zero comments.

 

In summary this is great idea done badly: very badly.

 

It's not much use to pros -  no oscillator, dreadful design practice so won't give a good idea of any device limitations and is hopeless as a reference design. It's not much use for learning either -  the low price is great but the total lack of any kind of decent tutorial stuff is a huge negative.

 

So unless, like me, you just have to get hold of the UP5K, this isn't a very good buy - even at $7.99.

 

MK