atapi cd-rom

Go To Last Post
10 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

maybe somebody have experience with cd-rom(atapi) projects? I cannot talk to my device, all it understands is reset. Every time i try to read status register i get almost all bits on. My wiring and code seems to be ok, pata cable is master side to cd-rom and system side to microcontroller, jumper is on master. Any ideas?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There used to be a number of working projects in the interwebs. Last time i built a cdrom interface was 14 years ago. I think a Google is in order.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

well, i found some projects and also i found atapi reference d1532v2r1a, however, i am still confused with asserting/negating command and control registers. Could somebody please explain me the logic of cs0 and cs1 in the table 41 in page 82? I tried to add a document but the site didn't allow it (probably too big).

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Gytis111 wrote:
well, i found some projects and also i found atapi reference d1532v2r1a, however, i am still confused with asserting/negating command and control registers. Could somebody please explain me the logic of cs0 and cs1 in the table 41 in page 82? I tried to add a document but the site didn't allow it (probably too big).

As far as I remember, these chip selects are active low, so in idle state you keep both high. The primary chip select is cs0, so bring it low when you want to talk there (1xx in PC) and set it high after use. If you need to use secondary chip select for some registers, you bring cs1 low while talking (3xx in PC). So only one of cs pins can be low but never both.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi jepael,

if cs0(/CS1FX) is command register pin and cs1(/CS3FX ) - control, then i think i get it and one of the sites has unfairly tricked me.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi again,

now i am having some problems with sending command packets, most of commands doesn't work and when i check error register and sense keys i get "ATAPI CD-ROM Drive reset or medium change since last command", but my drive doesn't look like resetting. Any tips what may cause this error?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

in specs it also says
"The ATAPI CD-ROM Drive shall generate a unit attention whenever the ATAPI CD-ROM Drive has been reset by a hard
reset condition, or by a power-on reset."
Does that mean that i have to do a soft reset to make it disappear?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

well it worked i managed to open a tray. It seems that registers must be initialised after soft reset as well, which i did not do.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There is a clue in the thread title: "Atapi". Did you search and find the ATAPI-IDE specification. There have been many issues of it but all the later ones are to do with HDD improvements like UDMA levels and so on. I think something like V3 was "simple" and gives you details of the many layers of the ATAPI-IDE interface standard right from the low level signals to the high level commands.

EDIT: a quick Google arrives here:

http://www.ata-atapi.com/

that site wrote:
If you are working with CD or DVD devices (PATAPI or SATAPI) then you also need the SCSI Multi Media Commands (MMC) document. Do not confuse the SCSI MultiMedia Commands (MMC) document with the Multi Media Card (MMC) specification (see below). The SCSI MMC document can be found at t10.org

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi cliff

if by atapi-ide specification you mean sf-8020, then yes, i have it, and i found it very useful. Just that the project i used didn't work out of the box and i did't want to dig in to all the specifications. Now with tray opened i think i can move on to more intresting stuff. That's what this grumbling of mine was all about.