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1  Using Arduino / Storage / Re: Interfacing to SD card using sparkfun logic level changers on: July 29, 2011, 08:14:50 pm
The problem was that I had my TX and RX lines backwards. T

I figured that out after I replaced it with a 74HC4050 circuit.
2  Using Arduino / Storage / Interfacing to SD card using sparkfun logic level changers on: July 21, 2011, 03:53:49 am
Hi All,

I've got a pretty weird problem. I'm trying to interface to a microSD card using two of sparkfun's logic level changers: http://www.sparkfun.com/products/8745

I've got them set up like this:



Please excuse the horrid circuit diagram.

I've eliminated most of the obvious failure modes; drawing too much power from the arduino's 3.3v (powered it independantly from a 3.3v rail on an ATX PSU), pins plugged into the wrong place (checked four or five times) and basic electrical faults (half an hour with a multimeter). I've tried two different microSD cards that have been independantly verified as being A-OK, neither are kingston branded, and both were FAT32. I'm connecting to the microSD card via an SD-to-microSD adaptor. The adaptor works, I've measured all connections from the pads on the card.

I'm using the bog-standard SD card test sketch that comes with arduino 22. I'm using a 2560, the uno mega.

Any ideas?

Thanks,
Tjhowse.
3  Forum 2005-2010 (read only) / Uno Punto Zero / Re: Tutorial - How to change firmware on 8u2 on: November 17, 2010, 03:36:51 am
Found a solution to my problem:

http://www.avrfreaks.net/index.php?module=Freaks%20Files&func=viewFile&id=3842&showinfo=1

These drivers were signed by some generous avrfreak, and work with the Uno under Win7 64b. Happy days!
4  Forum 2005-2010 (read only) / Uno Punto Zero / Re: Tutorial - How to change firmware on 8u2 on: October 27, 2010, 12:50:54 am
Awesome work! I wasn't looking forward to working out all this stuff on my own.

The only problem I've encountered is loading the DFU drivers in windows 7. It seems they aren't signed so win7 refuses to allow access to the device via Flip. I had to install it on an XP machine before I could write my newly compiled .hex to the 8U2.

There are ways of making win7 load unsigned drivers in test mode, but this is cumbersome.
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