CD drive: Difference between revisions

From NeoGeo Development Wiki
Jump to navigation Jump to search
m (Split)
(3 intermediate revisions by the same user not shown)
Line 1: Line 1:
[[File:Cd2_cdboard1.jpg|thumb|right|CD2 CD drive board.]]
[[File:Cd2_cdboard1.jpg|thumb|right|Top-loading drive control board.]]


The part that fails before everything else in [[CD systems]]. Made of a control board and an [[optical pickups|optical pickup]].
The part that fails before everything else in [[CD systems]]. Made of a control board and an [[optical pickups|optical pickup]].
Line 6: Line 6:


The control board has:
The control board has:
* A 4-bit maskROM MCU (Sony CXP5084), taking care of operation sequencing and communication with the NeoGeo.
* A 4-bit mask ROM MCU (Sony CXP5084), taking care of operation sequencing and communication with the NeoGeo.
* A DSP (Sony CXD2500) to process analog data from the pickup.
* A DSP (Sony CXD2500) to process analog data from the pickup.
* A servo controler (Sony CXA1372) to drive the pickup coils for tracking and focus.
* A servo controler (Sony CXA1372) to drive the pickup coils for tracking and focus.
* A spindle and sled motor driver (Rohm BA6396).
* A spindle, sled (and tray) motor driver.


=Connections=
=Connections=


Some say the protocol was standard for the time, but clear information is hard to find. This was guessed from the [[system ROM]] disassembly and a logic analyzer.
Some say the protocol was standard for the time, but clear information is hard to find. This was guessed from the [[system ROM]] disassembly, Sega MegaCD documents and a logic analyzer.
 
==Top-loading model==


Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):
Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):
Line 58: Line 60:
| rowspan="4" | Data
| rowspan="4" | Data
| rowspan="4" | Both
| rowspan="4" | Both
| rowspan="4" | 4-bit data bus
| rowspan="4" | 4-bit command/status data bus
|-
|-
| 7
| 7
Line 122: Line 124:


Missing: /RESET, C2PO, and 16MHz.
Missing: /RESET, C2PO, and 16MHz.
==Front-loading model==
Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):
{| class="regdef"
|'''Pin #'''
|'''Name'''
|'''Type'''
|'''Direction'''
|'''Description'''
|-
| 1
| SGND
| Power
| -
| Ground
|-
| 2
| SVCC
| Power
| -
|
|-
| 3
| VCC
| Power
| -
|
|-
| 4
| WFCK
| Clock
| Output
| Write Frame Clock
|-
| 5
| GND
| Power
| -
| Ground
|-
| 6
| SCOR
| Pulse
| Output
| Subcode sync
|-
| 7
| MUTE
| ?
|
|
|-
| 8
| SBSO
| Data
| Output
| Subcode data
|-
| 9
| EXCK
| Clock
| Input
| Subcode clock
|-
| 10
| EMP
| ?
| ?
| EMPty ?
|-
| 11
| DOUT
| Data
| Output
| ?
|-
| 12
| 6MHz
| Clock
| ?
| ?
|-
| 13
| LRCK
| Clock
| Output
| DATA L or R channel (44100Hz)
|-
| 14
| DATA
| Data
| ?
| Data stream
|-
| 15
| BCLK
| Clock
| Output
| DATA bit clock (44100 * 24 * 2 = 2.12MHz)
|-
| 16
| C2PO
| Data
| Output
| Error flag
|-
| 17
| rowspan="4" | DB0~3
| rowspan="4" | Data
| rowspan="4" | Both
| rowspan="4" | 4-bit command/status data bus
|-
| 18
|-
| 19
|-
| 20
|-
| 21
| HOCK
| Clock
| Input
| Communication clock from CDC
|-
| 22
| RESET
| Pulse
| Input
| The name says it all
|-
| 23
| /IRQ
| Signal
| Output
| Asks the CDC for a data exchange
|-
| 24
| L-MUTE
| ?
|
|
|-
| 25
| CDCK
| Clock
| Output
| Communication clock to CDC
|}


=Communication=
=Communication=
Line 129: Line 281:
[[File:Cdunit4bit.png]]
[[File:Cdunit4bit.png]]


* The CDD regularly (~64Hz) sends a low pulse on its /IRQ output to initiate a data exchange.
* The CDD regularly (~64Hz not 75) sends a low pulse on its /IRQ output to initiate a data exchange.
* HOCK goes low, indicating that the CDC aknowledges the request. The 4-bit bus direction is set to CDD to CDC.
* HOCK goes low, indicating that the CDC aknowledges the request. The 4-bit bus direction is set to CDD to CDC.
* CDCK goes low, indicating that the CDD is starting to send its status data (green A). Diagram fix: A should be ready on CDCK low.
* CDCK goes low, indicating that the CDD is starting to send its status data (A).
* HOCK goes high and the CDC reads the status data (A).
* HOCK goes high and the CDC reads the status data (A).
* CDCK returns high.
* CDCK returns high.
* HOCK returns high.
* HOCK returns low.
* CDCK goes low, the B word is ready.
* CDCK goes low again, the B word is ready.
* The cycle continues on for 10 words.
* The cycle continues on for 10 words...


(The delay here is not necessary, but it can be seen on the NeoGeo CD and is caused by the system ROM preparing stuff).
(The delay here is not necessary, it is seen on the NeoGeo CD because of the [[system ROM]] preparing stuff).


* HOCK goes low and the 4-bit bus direction is inverted (CDC to CDD). The command data is set (red A).
* HOCK goes low and the 4-bit bus direction is reversed (CDC to CDD). The first command word is set (K).
* CDCK goes low, indicating that the CDD has read the data (A).
* CDCK goes low, indicating that the CDD has read the data (A).
* HOCK returns high.
* HOCK returns high.
* CDCK returns high.
* CDCK returns high.
* HOCK goes low, the B word is ready.
* HOCK goes low again, the B word is ready.
* The cycle continues on for 10 words.
* The cycle continues on for 10 words...


==Status data (green)==
==Status data (green)==


* A: Status - 1=playing, 2=seeking, 4=paused, 9=idle, 14=stopped
* A: Status
** 0=Stop mode
** 1=Playing data or music
** 2=Seeking
** 4=Paused
** 5=Tray opened
** 6=Comm. checksum error
** 7=Command error
** 8=Function error (mech/laser ?)
** 9=Reading TOC
** 10=Sled moving
** 11=Couldn't focus, no disk
** 12=Sled at edge, end of disk
** 14=Tray moving
** 15=In test mode
* B: Status
* B: Status
* C: Minutes high digit
* C: Minutes high digit
Line 162: Line 328:
==Command data (red)==
==Command data (red)==


* A: Command
* K: Command
* B~I: Depends on command
* L~S: Depends on command (see below)
* J: Checksum (see below)
* T: Checksum (see below)


==Checksum==
==Checksum==
Line 174: Line 340:
See [[CD drive commands]].
See [[CD drive commands]].


==Adjustments==
==Adjustment pots==


To do !
To do !


[[Category:Chips]]
[[Category:Chips]]
[[Category:Repairs]]
[[Category:CD systems]]
[[Category:CD systems]]

Revision as of 22:48, 20 April 2019

File:Cd2 cdboard1.jpg
Top-loading drive control board.

The part that fails before everything else in CD systems. Made of a control board and an optical pickup.

The NeoGeo CD top-loading model drive was made by Sony. The CDZ one was made by Sharp ?

The control board has:

  • A 4-bit mask ROM MCU (Sony CXP5084), taking care of operation sequencing and communication with the NeoGeo.
  • A DSP (Sony CXD2500) to process analog data from the pickup.
  • A servo controler (Sony CXA1372) to drive the pickup coils for tracking and focus.
  • A spindle, sled (and tray) motor driver.

Connections

Some say the protocol was standard for the time, but clear information is hard to find. This was guessed from the system ROM disassembly, Sega MegaCD documents and a logic analyzer.

Top-loading model

Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):

Pin # Name Type Direction Description
1 CDCK Clock Output Communication clock to CDC
2 ? ? ? High ?
3 /IRQ Signal Output Asks the CDC for a data exchange (low pulse at ~64Hz)
4 ? ? ? High ?
5 HOCK Clock Input Communication clock from CDC
6 D0~3 Data Both 4-bit command/status data bus
7
8
9
10 ? ? ? ?
11 BCLK? Clock Output Serial bit clock, should be 44100 * 32 = 1.4112MHz
12 SDATA Data Output Serial data
13 LRCK Signal Output I2S word clock, should be 44100Hz. Audio L/R switch for the DAC.
14 D/M ? Signal Output Data/Music. Low during music playback ?
15 GND Power - Ground
16 5V Power - +5V for logic
17 9V Power - +9V for motors and coils
18 GND Power - Ground

Missing: /RESET, C2PO, and 16MHz.

Front-loading model

Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):

Pin # Name Type Direction Description
1 SGND Power - Ground
2 SVCC Power -
3 VCC Power -
4 WFCK Clock Output Write Frame Clock
5 GND Power - Ground
6 SCOR Pulse Output Subcode sync
7 MUTE ?
8 SBSO Data Output Subcode data
9 EXCK Clock Input Subcode clock
10 EMP ? ? EMPty ?
11 DOUT Data Output ?
12 6MHz Clock ? ?
13 LRCK Clock Output DATA L or R channel (44100Hz)
14 DATA Data ? Data stream
15 BCLK Clock Output DATA bit clock (44100 * 24 * 2 = 2.12MHz)
16 C2PO Data Output Error flag
17 DB0~3 Data Both 4-bit command/status data bus
18
19
20
21 HOCK Clock Input Communication clock from CDC
22 RESET Pulse Input The name says it all
23 /IRQ Signal Output Asks the CDC for a data exchange
24 L-MUTE ?
25 CDCK Clock Output Communication clock to CDC

Communication

CDD to CDC communication uses a special protocol handled by the system ROM. NEO-MGA provides the I/Os through registers REG_CDDCTRL, REG_CDDINPUT, REG_CDDOUTPUT.

  • The CDD regularly (~64Hz not 75) sends a low pulse on its /IRQ output to initiate a data exchange.
  • HOCK goes low, indicating that the CDC aknowledges the request. The 4-bit bus direction is set to CDD to CDC.
  • CDCK goes low, indicating that the CDD is starting to send its status data (A).
  • HOCK goes high and the CDC reads the status data (A).
  • CDCK returns high.
  • HOCK returns low.
  • CDCK goes low again, the B word is ready.
  • The cycle continues on for 10 words...

(The delay here is not necessary, it is seen on the NeoGeo CD because of the system ROM preparing stuff).

  • HOCK goes low and the 4-bit bus direction is reversed (CDC to CDD). The first command word is set (K).
  • CDCK goes low, indicating that the CDD has read the data (A).
  • HOCK returns high.
  • CDCK returns high.
  • HOCK goes low again, the B word is ready.
  • The cycle continues on for 10 words...

Status data (green)

  • A: Status
    • 0=Stop mode
    • 1=Playing data or music
    • 2=Seeking
    • 4=Paused
    • 5=Tray opened
    • 6=Comm. checksum error
    • 7=Command error
    • 8=Function error (mech/laser ?)
    • 9=Reading TOC
    • 10=Sled moving
    • 11=Couldn't focus, no disk
    • 12=Sled at edge, end of disk
    • 14=Tray moving
    • 15=In test mode
  • B: Status
  • C: Minutes high digit
  • D: Minutes low digit
  • E: Seconds high digit
  • F: Seconds low digit
  • G: Frames high digit
  • H: Frames low digit
  • I: Extension
  • J: Checksum (see below)

Command data (red)

  • K: Command
  • L~S: Depends on command (see below)
  • T: Checksum (see below)

Checksum

The checksum digit is the sum of all 9 previous digits, + 5, XOR 15, modulo 15: ((sum + 5) ^ 0xF) & 0xF.

Commands

See CD drive commands.

Adjustment pots

To do !

Retrieved from "https://wiki.neogeodev.org/index.php?title=CD_drive&oldid=6473"