Hi,
  Once again, it seems I've picked a project that has a very low chance o=
f
success (well, in its current form anyway).
  I want to connect a MultiMediaCard up to a PIC16F628 (or 16F874, I've g=
ot
both), but there's a slight problem - my PIC programmer (a VOTI Wisp628)
won't work below 3.3V. The same applies to my serial port converter, so I
can't just use a bootloader and a 16F874.
  Now, the only way I can see out of this problem would be to use a split
power supply - 5V for the PIC, 3.3V for the MultiMediaCard. This means I =
get
the fun job of setting up a levelshifter - fair enough, but I haven't got=
 any
MOSFETs or NPN transistors left (hard to believe, but it's true!)
  Can anyone forsee any problems with me using the following circuit to
convert from 5V to 3.3V?

                          + 3V3
                          -----
                            |
                            > 4k7
                            <
                            >
                            *-----------O SIG OUT
                           \|  PNP
             4k7      B | |/_\ E
SIG IN  O---/\/\/\------|<
                        |  \   C
                            |
                          -----
                           GND
                          =20
I intend to use the same sort of circuit to convert between 3.3V and 5V (=
MOSI
from the MMC to the PIC), except the 3V3 line will be connected to 5V
instead. Can anyone see any problems with this circuit? Having just spent=
 =A320
(about $35) on an MMC, I'm not too keen on seeing it imitate a firework o=
n
its first power cycle...
Just to finish off, does anyone know if there's a slightly simpler guide =
to
MMCs than the Sandisk "Multimediacard Product Manual"? Perhaps one that
includes some basic "write all zeroes to a sector", "read from a sector",
"erase a sector" type code?

Thanks.
--=20
Phil.                              | Acorn Risc PC600 Mk3, SA202, 64MB, 6=
GB,
philpem@dsl.pipex.com              | ViewFinder, 10BaseT Ethernet, 2-slic=
e,
http://www.philpem.dsl.pipex.com/  | 48xCD, ARCINv6c IDE, SCSI
... This tagline was reclaimed and is not yet stolen.

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