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Old 03-12-2008, 10:43 PM   #31
freqmax
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Default Re: Questions about Minimig future

Quote:
alexh wrote:
Quote:
ChuckT wrote:
why be stuck with one or two gigs when you can now buy cards up to 16 gigs?
I've seen MMC cards upto 8GB and they make SD cards upto 32Gbytes but I'm not too sure they work with MiniMig.
Creating SDHC support should be easy.
Doesn't require any hardware modifications asfaik. So an MCU software update should be able to do it.
And you can use (non-SDHC) 4GB cards right now in minimig asfaik.
Even FAT16 manages 4 GB. (anyway 4GB is the limit of FFS anyway asfair).

Quote:
ChuckT wrote:
I want it to have an HDMI port or cable for modern televisions
Why HDMI? Modern budget TV's dont have HDMI. They do however have component or VGA.

MiniMig as it shipped has two output modes, 31KHz VGA and 15KHz RGB (SCART). Add to that I am 80% sure I could change MiniMig's core to support component too.

That covers vast majority (all?) modern TV's![/quote]

Even budget TVs now get DVI or HDMI. In Europe component is not as common as SCART. The Xilinx Spartan-3x series can produce dvi/hdmi out of the box asfaik. Provided proper LVDS termination & impedance is used (yes I have investigated the matter in depth).

Quote:
ChuckT wrote:
If my Amiga was working, I would consider getting a Minimig as a backup but without me being able to get files over to the Minimig, getting one doesn't help me port the files over.
You could use the 4x spare minimig IOs and a MCU (like PIC) to fairly easy create something along the lines of CatWeasel.
Other than that there's the Amiga floppy reader project. Or get an Amiga and use rs232, or use Amiga with an HDD, then connect the HDD to the PC (so I did).
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Old 03-13-2008, 02:21 AM   #32
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Default Re: Questions about Minimig future

Quote:
freqmax wrote:
The Xilinx Spartan-3x series can produce dvi/hdmi out of the box afaik. Provided proper LVDS termination & impedance is used (yes I have investigated the matter in depth).
You sure? I am not as certain. Both DVI and HDMI uses TMDS not LVDS.
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Old 03-13-2008, 04:34 AM   #33
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Default Re: Questions about Minimig future

Quote:
You sure? I am not as certain. Both DVI and HDMI uses TMDS not LVDS.
DVI/HDMI uses TMDS as you state.
I just had a quick look again at the specs for LVDS and TMDS and I can not see a reason why you can't drive a TMDS receiver with LVDS transmitter.
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Old 03-13-2008, 05:27 AM   #34
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Default Re: Questions about Minimig future

Quote:
nBit7 wrote:
I can not see a reason why you can't drive a TMDS receiver with LVDS transmitter.
I am not an analog expert but looking at the specs I'd say you were wrong.

Shame MiniMig doesn't use a Spartan 3A cos in addition to LVDS it has TMDS I/O

http://www.xilinx.com/support/documentation/data_sheets/ds529.pdf

Take a look at Page 20
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Old 03-13-2008, 05:48 AM   #35
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Default Re: Questions about Minimig future

Quote:
nBit7 wrote:
Quote:
You sure? I am not as certain. Both DVI and HDMI uses TMDS not LVDS.
DVI/HDMI uses TMDS as you state.
I just had a quick look again at the specs for LVDS and TMDS and I can not see a reason why you can't drive a TMDS receiver with LVDS transmitter.
Physically they do seem to be quite similar, but TMDS uses a more complex encoding scheme... For longer transmissions? Maybe you can fake that with LVDS?
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Old 03-13-2008, 06:13 AM   #36
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Default Re: Questions about Minimig future

This might be of interest

http://www.onsemi.com/pub_link/Collateral/NB4N316M-D.PDF
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Old 03-13-2008, 06:16 AM   #37
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Default Re: Questions about Minimig future

I am taking about the electrical LVDS standard not the protocol called 'LVDS Display Interface (LDI)'.

I think the big issue with using LVDS drivers is the Termination method used for TMDS. Otherwise the voltage differential swings are compatible (haven't looked at timing). Remember that absolute voltages don't really matter so long as they are in the common mode input voltage range.
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Old 03-13-2008, 06:18 AM   #38
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Default Re: Questions about Minimig future

Quote:
nBit7 wrote:
I am taking about the electrical LVDS standard not the protocol called 'LVDS Display Interface (LDI)'.
As am I. {Edit: Oops I see you were replying to Bloodline's post}
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Old 03-13-2008, 09:44 AM   #39
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Default Re: Questions about Minimig future

When I looked at the TMDS spec (from the DVI spec). I found it 's essentially the same electrically wise. What TMDS does is to send 8-bits and then add 2-bits that relate to coding. One bit indicate if the other bits are inverted in order to balance DC. So it should be doable.
Faster memory might be needed.

Btw,, Anyone knows a surface mount switched regulator that use a small amount of external components and with builtin switch transistor that:
Vin = +5V or +12V
Vout = 1.2V - 3.3V (will use 1.2V 1.8V 2.5V 3.3V)
Iout >= 2.3A
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Old 03-13-2008, 09:49 AM   #40
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Default Re: Questions about Minimig future

Quote:
freqmax wrote:
When I looked at the TMDS spec (from the DVI spec). I found it 's essentially the same electrically wise. [as LVDS]
Ah, you see I didn't. I think I need to go on a course in Analog electronics.
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Old 03-13-2008, 10:21 AM   #41
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Default Re: Questions about Minimig future

http://en.wikipedia.org/wiki/TMDS
"In the first stage each bit is either XOR or XNOR transformed against the previous bit, whilst the first bit is not transformed at all. The encoder chooses between XOR and XNOR by determining which will result in the fewest transitions; the ninth bit is added to show which was used. In the second stage, the first eight bits are optionally inverted to even out the balance of ones and zeros and therefore the sustained average DC level. The tenth bit is added to indicate whether this inversion took place."

bit0-7: Data
bit8: XOR or XNOR
bit9: Invert ..or not

I think bit8 might be a challenge to accomplish in a fast logic.

"The physical layer for TMDS is Current Mode Logic (CML), DC coupled and terminated to 3.3 Volts."

Essentially LVDS asfair. I think the docs said +/-100mV. So wikipedia is proberbly wrong at the volts level.
Xilinx Spartan-3/3E i/o mode LVDS25 should do it.
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Old 03-13-2008, 10:34 AM   #42
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Default Re: Questions about Minimig future


LVDS and CML 3.3v (DVI/HDMI) at the physical level don't look the same to me. But I stress I am not an analog person.
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Old 03-14-2008, 12:17 AM   #43
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Default Re: Questions about Minimig future

First one to try will find out :-D

Spartan-3A TMDS out-of-the-box is only available in non-handsoldering BGA packages.
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Old 03-14-2008, 01:26 AM   #44
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Default Re: Questions about Minimig future

Actually there is one TQFP part, but it's only 144 I/O (which is less than the current MiniMig) and not suitable.

Any future MiniMig board will have to use BGA chips.

I've got a BGA rework workstation and a flow solder oven ;-)

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Old 03-14-2008, 01:48 AM   #45
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Default Re: Questions about Minimig future

Quote:
LVDS and CML 3.3v (DVI/HDMI) at the physical level don't look the same to me.
As I said before the physical voltage levels are not that important. Its the difference in voltage between the complementary pair that decides if it is a logic 1 or 0.
However the voltages must remain in the common mode window of the receiver. LVDS normally terminated by 100 ohms generates at least 200mV differential at the receiver which is more than the 150mV receive window shown in the DVI spec.
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