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Discussion Groups | FPGA-CPU | Prototyping board for Altera ACEX

This list is for discussion of the design and implementation of field-programmable gate array based processors and integrated systems. It is also for discussion and community support of the XSOC Project (see http://www.fpgacpu.org/xsoc).

Prototyping board for Altera ACEX - Martin Schoeberl - May 24 12:02:00 2002


I'm building a new board with Altera EP1K50 for my java processor (see www.jopdesign.com). I would like to split the cost for PCB, parts, board routing,... The board is a good base to play with cpu design. Static ram and flash is connected to the fpga. All unused pins (56) are routed to two expansion connectors (DIL like).

The board contains:
EP1k50tc144-3 (1k30, 1k100 are possible)
voltage regulators (5V, 3V3, 2V5)
crystal clock
512kB Flash (for FPGA configuration and program)
128kB Ram (512k possible)
byteblaster port
watchdog with led
EPM7032 PLD to load FPGA from flash (on watchdog reset)
serial interface (MAX323A)

If anybody interested I can send the schmatics in EAGLE format (can be viewed with the free version).
Martin [Non-text portions of this message have been removed]




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Re: Prototyping board for Altera ACEX - N S - May 24 12:46:00 2002

Hi,
The board is very interesting.
I also plan to make such a board for my m65, my80
and other projects.
How about the width of the ram/flash memories?

And what I need more is:

1) VGA connector.
2) USB host connector.
3) USB target connector.
4) RCA pin connectors with simple RC D/A.

Can you incorporate these I/Fs?

__________________________________________________





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Re: Prototyping board for Altera ACEX - Martin Schoeberl - May 25 3:18:00 2002

> How about the width of the ram/flash memories?

ram and flash are 8 bit wide (TSOP case) to save space and pins.

> And what I need more is:
>
The idea for the board is to integrate all necessary parts to make a cpu
'living', but not more. You can easy add any periphery on a second board via
the pin heads.

> 1) VGA connector.

If you need only some colors (eg. 32) you can make a VERY simple VGA
connector. I did it some time ago. A simple discrete 2 bit DAC for each
channel with two resistors (470 and 1k):

470
_____
HBit O----| |-----o
----- |
|
1k |
_____ |
LBit O----| |-----o
----- |
|
|
-
| |
| | 75 (video input)
| |
-
|
|
|
---

The 75 ohm resistor is the input of the monitor.
Pins of the VGA connector:

1 Red Video
2 Green Video
3 Blue Video
4 Monitor ID Bit 2
5 Ground
6 Red Ground
7 Green Ground
8 Blue Ground
9 Key (no pin)
10 Sync Ground
11 Monitor ID Bit 0
12 Monitor ID Bit 1
13 Horizontal Sync
14 Vertical Sync
15 Monitor ID Bit 3

I can send you a VHDL file to generate the sync signals.

> 2) USB host connector.
> 3) USB target connector.

Thats not so easy. Do you want to build an USB interface in the FPGA or do
you want to use an extern chip?

> 4) RCA pin connectors with simple RC D/A.

Like the VGA connector. But you can build a DAC with only one R and one C
and generate the value with PWM. I used this simple idea to build an ADC
with two R's and one C. You can find VHDL source and 'schematics' on
www.jopdesign.com under download. Look for sigdel.vhdl.

Martin





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Re: Prototyping board for Altera ACEX - N S - May 25 7:12:00 2002

Hi,
Thank you for your reply.

> ram and flash are 8 bit wide (TSOP case) to save
> space and pins.

Though some of my project will need 16bit wide,
many of them will fit with 8bit wide.
And the board will be still useful enough.

> The idea for the board is to integrate all necessary
> parts to make a cpu
> 'living', but not more. You can easy add any
> periphery on a second board via
> the pin heads.

I think I know what you want to make.
But I have EP1K50 board without memory, and
if I need second board, then I can place
memories on it.
What I am intended to is a stand-alone PC for kids.
I have grown up with VIC20, and I think these type
of simple PC will be still useful for many
people. I think it is possible to make a stand-alone
with video/keyboard interfaces on it with EP1K50.

> If you need only some colors (eg. 32) you can make a
> VERY simple VGA
> connector. I did it some time ago. A simple discrete
> 2 bit DAC for each
> channel with two resistors (470 and 1k):

Yes I know, what I really was going to make was
NTSC composite color signal with some R and C.
I made full timing chart and signal level chart.
Then the rest is to make a circuit. It is easy.

> > 2) USB host connector.
> > 3) USB target connector.
>
> Thats not so easy. Do you want to build an USB
> interface in the FPGA or do
> you want to use an extern chip?

I have USB interface logic under the debug.
It can reply to host's setup requests, but
with some strange firmware or logic bug
it is still under the construction. I hope
it will work in a few weeks(or hopefully days).
Then what I need is level converter chip
and the connector. It may work without
level converter but simple R connection.

> > 4) RCA pin connectors with simple RC D/A.
>
> Like the VGA connector. But you can build a DAC with
> only one R and one C

Yes, that is just I planned to do so.

Anyway it will be a good board for many.
Do you know the follwing site?

http://www.olimex.com/pcb/index.html
__________________________________________________





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Re: Prototyping board for Altera ACEX - Martin Schoeberl - May 26 12:43:00 2002

> > ram and flash are 8 bit wide (TSOP case) to save
> > space and pins.
>
> Though some of my project will need 16bit wide,
> many of them will fit with 8bit wide.
> And the board will be still useful enough.

I'm using intern (FPGA) memory with 32 bit interface (JOP is a 32 bit
processor). The internal memory works as a kind of cach.

> I think I know what you want to make.
> But I have EP1K50 board without memory, and
> if I need second board, then I can place
> memories on it.

If you want exact your IO on the board, you have to build one yourself :-)
The way my board could help you is that you don't have to route the hard
parts (like ram/flash interfacing, find the minimal place to get from the
0.5mm spacing to a 100 mil grid,...). You can think about this board as a
modul for the cpu core with easy spacing (100mil pin heads) for the rest.

> people. I think it is possible to make a stand-alone
> with video/keyboard interfaces on it with EP1K50.
If you need more than text output on the video you will need fast ram. > Yes I know, what I really was going to make was
> NTSC composite color signal with some R and C.
> I made full timing chart and signal level chart.
> Then the rest is to make a circuit. It is easy.
For b/w this is easy, but for color you'll need some analog cicuit for he
modulation.

> I have USB interface logic under the debug.
cool, good luck :-)

> Anyway it will be a good board for many.
> Do you know the follwing site?
>
> http://www.olimex.com/pcb/index.html
>
Not bad, but there minimum drill size is a little bit to big for a board
with TQFP-144 parts I think. I made my prototyps with
http://www.pcbpool.com/. A bit more expensive.

Martin




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