Minimig v1.1 ARM Hardfile Demonstration

[mikej]

Yaqube, could you clarify which pads needs to be shorted and why?

"But unfortunately the original Minimig board design imposes a limitation on the maximum communication speed with an SD/MMC card. To overcome this problem you need to short two pads of two resistors (very simple soldering task). Otherwise the emulated hard disk transfer speed is limited to ca 200 KB/s."

I would like to make sure the FpgaArcade dev board I have developed can run at the faster speed. It uses an AVR rather than a PIC and dual SPI controllers so I can suck a block fro the SD card while sending the last one to the FPGA. It won't help if I am limited to 200KB however..

Thanks,
Mike.

[mikej]

Great, thanks for the info. I remember talking to Dennis about this a while back actually. That was the other reason I went for a dedicated SPI connection to the SD card with a source terminated clock so I shouldn't have this problem. The (slightly out of date) schematics are up on line if you want to have a look.

I remember another issue somebody mentioned that if you were doing a mode change from MMC to SD then you needed to reboot the SD card. This would require a FET on the power supply to the SD card which I would rather not add. Anybody come across a need for this?

Cheers,
Mike.

[mikej]

ah, I found the power cycling issue, it was from my mate Arnim from Opencores. If you switch the card from SD mode to SPI mode then you can only switch back to SD/MMC mode by power cycling the card. This is not an issue for us as both the FPGA and the boot controller both talk SPI.

/Mike