Vincullum or DOSonChip?

Spork Frog

I'm looking for a way to add mass storage to my Propeller project easily. I know that there have been routines to interface to an SD card directly, but I think I'd rather stick with one of these, mainly because they can take advantage of some of the more advanced features of the FAT filesystem.

I don't care what kind of storage they use. (I know Vincullum=usb stick and DOSonChip=sd card.)

Anyone have experience with either and say which they think is better?

Mike Green

I only have a little experience with the DOSonChip and slightly more with the Vinculum. From my standpoint, there are problems with both of them, but the Vinculum is faster and better documented. I put together some test routines for the Vinculum that use SPI mode:

'' Test program for Vinculum and Propeller Demo Board

CON
  _clkmode  = xtal1 + pll16x
  _xinfreq  = 5_000_000

  RESET     = 0                   ' Vinculum /Reset
  SPI_CLK   = 1                   ' Vinculum Clock
  SPI_DATA  = 2                   ' Vinculum Data
  SPI_CS    = 3                   ' Vinculum Select
  EOL       = 13                  ' End of line (return)

OBJ
  key : "keyboard"
  dsp : "tv_text"

PUB start | t, s
  dsp.start(12)                   ' TV pin block for Demo Board
  key.start(26,27)                ' Keyboard pins for Demo Board
  dsp.str(string("Vinculum Test Program",EOL))
  outa[noparse][[/noparse]RESET]~                    ' Reset device
  dira[noparse][[/noparse]RESET]~~
  outa[noparse][[/noparse]SPI_CS]~                   ' Select normally low
  dira[noparse][[/noparse]SPI_CS]~~
  outa[noparse][[/noparse]SPI_CLK]~                  ' Clock normally low
  dira[noparse][[/noparse]SPI_CLK]~~
  dira[noparse][[/noparse]SPI_DATA]~                 ' Data initially input
  outa[noparse][[/noparse]RESET]~~
  s := 0
  waitcnt(clkfreq / 4 + cnt)      ' Wait for 250ms initialization
  repeat
    if s == 0                     ' Buffer not full in Vinculum?
      s := key.key                ' Look for typed character
    if s > 0                      ' Character pending?
      if (transfer(false,false,s) & 1) == 0
        dsp.out(s)                ' If transmitted ok, echo to display
        s := 0                    ' Allow another
    if ((t := transfer(true,false,0)) & 1) == 0
      t := t >> 1 & $FF           ' If character read from Vinculum
      if t & $7F => " " or t == EOL
        dsp.out(t)                ' Display all displayable characters
      else
        dsp.out("{")              ' Or display hex code of others
        dsp.hex(t,2)
        dsp.out("}")

PRI transfer(read,status,data) | i, mask
'' Transfer data to/from Vinculum USB Host in SPI mode
  data := $800 | $400 & read | $200 & status | data << 1
  mask := $800
  outa[noparse][[/noparse]SPI_CLK]~~                 ' At least one clock prior to selecting
  outa[noparse][[/noparse]SPI_CLK]~
  outa[noparse][[/noparse]SPI_CS]~~                  ' Select chip
  repeat i from 1 to 12           ' Start, direction, address, 8 data, status
    dira[noparse][[/noparse]SPI_DATA] := i < 4 or i < 12 and not read
    outa[noparse][[/noparse]SPI_DATA] := (data & mask) > 0
    result |= mask & (ina[noparse][[/noparse]SPI_DATA] > 0)
    outa[noparse][[/noparse]SPI_CLK]~~               ' Data valid on positive edge of clock
    dira[noparse][[/noparse]SPI_DATA]~               ' Let data line float after hold time
    outa[noparse][[/noparse]SPI_CLK]~
    mask >>= 1
  outa[noparse][[/noparse]SPI_CS]~                   ' Deselect chip
  outa[noparse][[/noparse]SPI_CLK]~~                 ' At least one clock after deselecting
  outa[noparse][[/noparse]SPI_CLK]~

Unsoundcode

Just out of interest you can have the best of both worlds with the Vdrive and this little gadget.

http://www.cyberguys.com/templates/searchdetail.asp?productID=9886

Jeff T.