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[mikej]

Btw.. do you happend to know if 1000BASE-T ethernet PHY will accept DC/DC switched regulator as power source?, esp of the AVDD inputs.

AVDD normally means analogue supply and should be quiet. You can either use a pi filter from the DC/DC supply with either a resistor or inductor (depending on current) and cap, but normally I would use a small LDO linear regulator.
/Mike

[Oliver]

Hi,

I used VHDL in uni. My advice would be to first make sure you have a reasonable understanding of transistors and logic gates. You don't need to know a lot about transistor physics, but some understanding of their operation, and the relationship between electronic signals and logic abstraction is good.

Have a look at clocked and unclocked gates, and check up on how feedback is used. I expect pretty much any introductory text on logic will suffice. Some examples which I think would be handy are the basic clocked and unclocked AND, NAND, OR, NOR, NOT (inverter), XOR gates, as well as the various types of flip-flop (this is a good introduction to the use of positive feedback), MUX (multiplexers), shift registers, etc.

It is also worth understanding binary arithmetic.

I think a pretty good first project is a simple arithmetic logic unit. You can make one from pretty basic sub-blocks, and then connect it all together with a 'case' statement (these are pretty handy in VHDL).

Introductory logic texts, and microprocessor texts can be bought very cheaply second hand (I have picked up a number of free ones at university book shops). There are also texts which cover introductory logic, and VHDL together. VHDL texts tend be a bit more expensive in the places I have looked. For logic texts, old editions are fine.

For my classes, it was usually people with a lot of programming background who had the most difficulty with VHDL. As Alex described, the habit of thinking in terms of purely sequential tasks can cause missunderstanding of what is being done. It's best to keep in mind that VHDL is a Hardware Descriptor Language, not a process description. Hope that makes sense. Coders in my class often wanted to do things in loops (which works), but ended up having misconceptions of what they had achieved.

I haven't used Verilog before, so would be keen to hear any further comparisons with VHDL, from anyone here.

I'm actually in a similar position to BinoX in wanting to explore this area further as a hobby, though I don't yet have the time available. I would be interested to hear further of people's experiences with development boards, however.

Cheers,

Oliver

[rkauer]

freqmax wrote:
Digilent have a an developer board for 59 USD

Btw, to anyone else.. seems digilent has refreshed their sortiment. 16M PSRAM.. ie just add m68k.. :-D

This is not "almost" the Minimig without the PIC, conectors and 68EC000?

[jkonstan]

A used digital design book with VHDL or Verilog is a good place to start. I prefer Verilog; however, I have learned VHDL as well. It is good to know both Verilog/VHDL because sooner or later you are going to get some code in the other language if you only learn one of them.

The Xilinx Spartan3e eval board & the Altera DE1/DE2 are pretty good for development as well.

Mike. You did a nice job on the VIC-20 port to the Spartan3e Eval board. The C code to convert the bin roms to VHDL was very useful. I got copies of my roms and rebuilt the VIC-20 project in Xilinx-ISE, and the VIC-20 is up and running !

FPGAs can be fun !

:-)

[rkauer]

Just to clarify: the board pointed is not sufficient to use as a Minimig "clone": it have not enough gates!:shrug:

You need to use this, instead. But the price is more than 99 bucks! So the Minimig still is more affordable...

[freqmax]

@alexh:
The National.com DP83865 in PQFP128 package. It uses 1.8V and 2.5V (see page 65).

The reason to favour switched regulator DC/DC is because it saves a lot of power when it's at a premium (and thermal issues).
It uses at 1.8V 0.430 A (0.774 W).

@mikej:
I assume you mean 2x capacitors + 1x inductor like this ..?
I'm leaning towards an linear regulator. Possible with LDO due their instability. But an DC/DC solution would been nicer

@rkauer:
It's definitly not something capable of Minimig. But it's useful as a starting point on the cheap.
Missing enough FPGA logics, and RAM mainly.

[Andeda]

If you choose VHDL then here are two good books who introduce you to the VHDL world:
Digital system design with VHDL and The designers guide to VHDL. Minus is that their both quite expensive.
Digital system design is maybe the one to start with, it is quite easy to read and understand.
Good luck.

[mikej]

@mikej:
I assume you mean 2x capacitors + 1x inductor like this ..?

pretty much, although it's only the cap on the chip side of the inductor which you need to add, you can assume there is local decoupling of the digital rail nearby.

look at page 65 of the datasheet.
They recommend using resistors rather than inductors, so the current requirement must be quite low for the analogue pins. Just follow the guidelines.

You can get dual output dc/dc which will make you 2v5 and 1v8 at 1A no problem.
/Mike