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Discussing the Open Source FPGA Amiga Project
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 Post subject: Re: minimig-de1 release 5
PostPosted: Wed Nov 28, 2012 8:40 pm 
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The simple "just adopt Tobi's old minimig_de2.qsf to the updated de1 setup by replacing the project file names without any further thinking" approach isn't working 100% (but pretty close).

I get "F 02" on the hex leds and the boot output on rs232, de1_boot.bin is loaded as well as kick.rom, but a black screen. I think i am pretty close and it's just the voideo dac which isn't driven in the right way. The screen syncs to 50hz/31khz and claims it sees a 640x480x50hz video mode. But the screen is just black. I'll dig a little deeper into this. Perhaps there's some blanking signal or similar ... i'll have to check the differences of de1 and de2 video.

Edit: Besides the 3*6 additional color bits i already took care of the de2 additionally has a pixel clock, blanking and a composite sync. Easy to wire up, but still 10 hours until i can give it a test. What's the pixel clock of the minimig? Tobi used the DRAM_CLK for this. It probably doesn't matter as it shouldn't make a difference if the video dac is fed with a multiple of the actual pixel clock as long as the pixel data is stable.


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 Post subject: Re: minimig-de1 release 5
PostPosted: Thu Nov 29, 2012 9:54 am 
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If you see kick.rom loading, that is a good sign - at least the ctrl part is working OK, and the TG68 & SDRAM cores too, probably, as the amiga-side CPU has to work OK to at least respond to the ctrl commands.

There's still a possibility of some SDRAM timings problem, but my guess would be it's the blanking signal - check how that was done before.
The clock should be OK, but it might be better to use the 28Mhz clock, as that will probably minimize any possible skew.

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 Post subject: Re: minimig-de1 release 5
PostPosted: Fri Nov 30, 2012 10:35 am 
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It works! The VGA adjustments did the trick. I have another small change for the VGA_BLANK generation and if that also works i'll send you the de2 related files. I'll also check the 28Mhz for video clock.


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 Post subject: Re: minimig-de1 release 5
PostPosted: Fri Nov 30, 2012 11:01 am 
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I have a feature request: As we all know the 50hz mode isn't accepted by all displays. By increasing the entire system clock by 10% the 28Mhz become 32 and the 7 become 8 and the resulting video output at 50hz is actually 56hz and vga compatible. I have tested that with tobi's old de2 build and it worked nicely there.

If you could put this onto one of the switches, that would be great!


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 Post subject: Re: minimig-de1 release 5
PostPosted: Fri Nov 30, 2012 2:03 pm 
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That is going to be problematic.

The cycloneII device used on the DE1 board has PLLs that cannot be reconfigured, so it is not possible to change the multiplier / divider in the PLL while running.

It also has just three clock outputs, which are already used for 118MHz logic clock, 118MHz SDRAM clock & 28MHz logic clock. The required 7MHz clock must already be generated with a logic counter.

I could setup the design to use two different PLLs, as there are still two unused, but that will probably negatively affect the stability of the design, especially since the FPGA is pretty filled up. I will try it though, but I have doubts it will work OK.

I could build a separate design with higher clocks, if anyone wants to use it.

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 Post subject: Re: minimig-de1 release 5
PostPosted: Fri Nov 30, 2012 7:20 pm 
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I sent you the de2 related files in PM.

Imho you just need one more pll to generate ~30Mhz from the 27Mhz and then optionally feed that instead of the 27Mhz into the existing amiga pll. I wouldn't expect aný negative impact.


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 Post subject: Re: minimig-de1 release 5
PostPosted: Fri Nov 30, 2012 7:28 pm 
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By increasing system cock, whole chipset simulation will speed-up.
Means, game and demo will run faster (almost as in 60Hz NTSC mode) and possibly the floppy drive access could no longer work properly.

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 Post subject: Re: minimig-de1 release 5
PostPosted: Fri Nov 30, 2012 9:13 pm 
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boing4000 wrote:
By increasing system clock, whole chipset simulation will speed-up.
Means, game and demo will run faster (almost as in 60Hz NTSC mode) and possibly the floppy drive access could no longer work properly.


Yes, everything is faster and sounds have a slightly higher pitch. Still better than a blank screen saying "out of sync". I only want this as an option. Most of the time it shouldn't hurt.

Why should the floppy be affected? You mean a real one?


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 Post subject: Re: minimig-de1 release 5
PostPosted: Sat Dec 01, 2012 11:47 am 
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Master of Gizmo wrote:
Why should the floppy be affected? You mean a real one?


At least in real Amiga hardware and MinimigV1 board the floppy drive don't work at faster DMA clock rate because the floppy drive still operate at same (original) speed while Amiga clock got faster.
Result is a DMA data timing mismatch.

If the PIC/ARM replacement in the Altera port also will work at faster clock speed to match DMA data flow, the higher system clock will work with floppy emulation, too.

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 Post subject: Re: minimig-de1 release 5
PostPosted: Mon Dec 03, 2012 8:21 am 
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boing4000 wrote:
If the PIC/ARM replacement in the Altera port also will work at faster clock speed to match DMA data flow, the higher system clock will work with floppy emulation, too.


I am pretty sure i only increased the amiga clock in tobi's old de2 setup. Many things have changed since then incl the entire io controller part, so it may actually not work anymore.


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