Hedghog II

[FRANK.C]

Hedghog II is mainly in response to the recent trouble with the EP2C5 FPGA boards.

Hedghog II for the most part it is the Same as Hedghog but with a few changes.
The biggest difference is the FPGA board is dispensed with. Now all the components are mounted on a single PCB.
The FPGA is changed to a more modern EP4CE6E22C8N.
The R2R DAC is changed from 9 bit to a 10 bit.
It now can be used in modulator only mode.
The video out socked is moved to the rear panel and an extra toggle switch is added to the front panel.
The DIP switch is now a 6 pole type.
It has a test mode that drives the Test card from the 50 MHz clock. This will allow the 405 side of the FPGA to be tested without the video clock been required and so should help to identify video decoder problems.

There are some circuit changes.
A 50 MHz oscillator feeds the FPGA. All other clocks are referenced from the 50 MHz clock. This includes a 14.31818 MHz clock for the video decoder which previously required it's own crystal.
The pull-up resistors for the switches have been removed and it now uses the weak pull-up's provided by the FPGA.
The unused section of the video amplifier chip is now used together with a analogue switch to enable it to be used in modulator only mode.
To provide all the required power rails there are now 5 voltage regulators 5V, 3.3V, 2.5V, 1.8V and 1.2V.
It still fits on a double sided PCB of the same dimensions as the Hedghog PCB and so will fit the same case.

All the files needed to build it can be downloaded here.

Frank

[Electricdreams]

I've not got round to building Hedgehog 1, will support still be available?

[FRANK.C]

Yes it will.

Hedghog II is an alternative rather than a replacement.


Frank

[Jac]

Hi Frank,

I noticed that it is not possible to download the Gerber files.



Jac

[FRANK.C]

Hi Jac
That's correct they are not downloadable. The files are already uploaded to PCBWay and if anyone wants PCB's they can be purchased from there.


Frank

[1100 man]

I was pretty impressed with myself for managing to solder the insanely small surface mount parts to the Hedhog 1 PCB's. Soldering that new FPGA chip into HH2 would drive me past the point of insanity!

I've just received my second EP2C5 board from China after a full 6 week wait. I've yet to see how viable it is- fingers crossed!

Cheers
Nick

[FRANK.C]

Hi Nick
It is a little more challenging but at least now you can chose your poison.

Frank

[Freya]

A suggestion for anyone building the HH2 would be to fit the main FPGA and its memory to the underside along with C14, then all the SMD caps and resistors, regulators and the JTAG socket on the top side of the board.
It will then program if you have done everything correctly.

Then the fun begins with all the remaining components on the underside.

[Escotto]

Is what Stephen described just about the best way of doing this or are there alternatives?

[Freya]

My Suggestion was based on the fact that the FPGA can be the hardest part to attach and possibly get wrong, by doing it first and getting it programmed gets it out of the way so the rest of the components can be added.