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Discussing the Open Source FPGA Amiga Project
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 Post subject: SPI mod
PostPosted: Wed Feb 01, 2012 6:14 pm 
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Joined: Wed Feb 01, 2012 10:41 am
Posts: 5
Hi,

I just got my Minimig in and I wondered about the SPI mod, but I needed to have some stuff?

1: ARM board (check)
2: 4MB memory (check)
3: Resistor bridge? (not sure)

Here's a picture of my board: http://www.retroforum.nl/gallery/image/ ... ende-case/

What exactly do I need to do to be able to enable the SPI thing?

Thanks!


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 Post subject: Re: SPI mod
PostPosted: Wed Feb 01, 2012 6:42 pm 
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Joined: Mon Dec 01, 2008 9:58 pm
Posts: 1568
Location: .de
MMdjkoelkast wrote:
What exactly do I need to do to be able to enable the SPI thing?


Welcome.
You need to solder a bridge between R50 and R51 to the side absend of the sd-slot (at the side to the s-ram chips).
After that the Fast SPI mode can be enabled without the risk of data-loss.

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 Post subject: Re: SPI mod
PostPosted: Wed Feb 01, 2012 6:47 pm 
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Joined: Wed Feb 01, 2012 10:41 am
Posts: 5
Could you please explain this "bridge"? R50 and R51 both have 2 sides, where to solder what exactly?
Or is there an image available of this mod?


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 Post subject: Re: SPI mod
PostPosted: Wed Feb 01, 2012 6:50 pm 
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Take a look at picture of 2nd posting.

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 Post subject: Re: SPI mod
PostPosted: Wed Feb 01, 2012 8:50 pm 
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Joined: Wed Feb 01, 2012 10:41 am
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Ok, done it!
Quite a fiddly job, but it went smooth. I didn't really notice the difference, but until now I only played adf games, so not that much more speed to be expected I guess.


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 Post subject: Re: SPI mod
PostPosted: Thu Feb 02, 2012 10:58 am 
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Joined: Mon Dec 01, 2008 9:58 pm
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Location: .de
ADF speed-up is not that much since its upper speed is imited due to the DMA transfer range.
HDF data transfer should grow a lot with enabled Fast-SPI mode. Depending on used SD-Card (size / class) a transfer rate of 2.0 to 2.3 MB/s is possible.

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 Post subject: Re: SPI mod
PostPosted: Thu Feb 02, 2012 11:06 am 
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Joined: Wed Feb 01, 2012 10:41 am
Posts: 5
I did notice that browsing through all ADF files went a lot smoother now, so it certainly helped there.
Haven't started with creating HDF files yet.


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 Post subject: Re: SPI mod
PostPosted: Fri Mar 09, 2012 7:35 pm 
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Joined: Thu Sep 24, 2009 8:07 am
Posts: 36
I'm considering bridging R50 & R51.

Q1: have any stability problems been reported with Fast-SPI enabled?

Q2: can the Minimig still be flawlessly used in non-fast-SPI, even if the hardware mod has been done?


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 Post subject: Re: SPI mod
PostPosted: Sat Mar 10, 2012 11:39 am 
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Until now the fast SPI function solve more problem then cause problem.
Some SDHC card even don't work at 8MHz (slow SPI mode) and only work at the 24MHz (fast) mode.

It is possible to switch back into 8MHz mode by holding down the MENU button on Minimig board while power-up. But this is not necessary and Fast SPI mode with soldering mod should be used to increase compatibility (and fun-with-Minimig ;)).

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 Post subject: Re: SPI mod
PostPosted: Sat Mar 10, 2012 3:23 pm 
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Joined: Thu Sep 24, 2009 8:07 am
Posts: 36
boing4000 wrote:
Until now the fast SPI function solve more problem then cause problem.

Solder iron heating up... :D


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