CompactFlash I/O

Comments

• Mike Green Posts: 23,101

  2012-07-20 09:27 edited 2012-07-20 09:27

  You need to look at the Wikipedia description of the CompactFlash card and its derivatives. Note that this uses a 50-pin interface which normally transfers 16 bits at a time. I don't recommend using this with the Propeller or any other micro because of the number of I/O pins required. You can always multiplex the I/O pins by adding some external latches and buffers, but that makes the interface more complicated.
  
  Note that the "micro" you refer to is a micro-processor, not a micro-controller like the Propeller. The difference in this case is that the Rabbit microprocessor has a full external memory and I/O bus with at least 20 address bits (1MB) and 8 data bits.
• Circuitsoft Posts: 1,166

  2012-07-20 09:30 edited 2012-07-20 09:30

  From what I understand, you can do 8-bit transfers if you strobe the pins right. I've seen references to that in other docs about using this chip with micros, but the doc I found didn't have complete details on that.
• Mike Green Posts: 23,101

  2012-07-20 09:43 edited 2012-07-20 09:43

  I suspect the CF card defaults to 8-bit transfers and you can probably get away with an 8-bit address bus. That's still a lot of I/O pins. Start with the Wikipedia article and follow some of the links to find the ATA and CF bus hardware descriptions.
• groggory Posts: 205

  2012-07-20 10:39 edited 2012-07-20 10:39

  Also, what draws you to using compactflash? SD is so much simpler when you're dealing with micros, and is cheap to boot
• Circuitsoft Posts: 1,166

  2012-07-20 11:05 edited 2012-07-20 11:05

  groggory wrote: »

  Also, what draws you to using compactflash? SD is so much simpler when you're dealing with micros, and is cheap to boot

  Circuitsoft wrote: »

  I have a CF WiFi card
• pedward Posts: 1,642

  2012-07-20 15:05 edited 2012-07-20 15:05

  Seems that SDIO was stillborn after the days of the Handspring devices that supported it.
• localroger Posts: 3,452

  2012-07-21 08:24 edited 2012-07-21 08:24

  Many moons ago I looked into CF I/O. I seem to recall determining that you need a minimum of 14 I/O lines to do CF transfers. CF is basically the same as parallel ATA hard drive interface and you can plug a CF card into an ATA hard drive socket with a passive adapter and it looks like a hard drive to the host.
• Circuitsoft Posts: 1,166

  2012-07-21 10:31 edited 2012-07-21 10:31

  I've read that you can do 8-bit I/O on a CF card, but ATA/IDE requires full 16-bit transfers.
• rallyordie Posts: 4

  2012-07-21 12:43 edited 2012-07-21 12:43

  I am designing a system now using CF and a PIC24. SD/MMC cards just don't cut it in wide-temp, high vibration applications. Google 'ELM FatFs' for an excellent tutorial on talking to CF and a FAT file system. Chan provides a reference design based on an AVR that is easily adapted to other processors.
  
  I looked at using the Propeller (I've used it on other projects), but plenty of I/O and the parallel master port makes it simple to implement a fast CF interface for the PIC24 without extra hardware.