CD drive: Difference between revisions

From NeoGeo Development Wiki
Jump to navigation Jump to search
m (Split)
m (Split)
 
(4 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 makes you wait and fails in [[CD systems]]. The ones used in the NeoGeo consoles are very similar to those found in the Sega CD. They're basically enhanced audio CD drives, which are also able to read CD-ROM data tracks.
 
Made of a control board and an [[optical pickups|optical pickup]].


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


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 CD 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 62:
| 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 123: Line 127:
Missing: /RESET, C2PO, and 16MHz.
Missing: /RESET, C2PO, and 16MHz.


=Communication=
==Front-loading model==


CDD to CDC communication uses a special protocol handled by the [[system ROM]]. {{Chipname|NEO-MGA}} provides the I/Os through registers {{Reg|REG_CDDCTRL}}, {{Reg|REG_CDDINPUT}}, {{Reg|REG_CDDOUTPUT}}.
Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):


[[File:Cdunit4bit.png]]
{| class="regdef"
 
|'''Pin #'''
* The CDD regularly (~64Hz) sends a low pulse on its /IRQ output to initiate a data exchange.
|'''Name'''
* HOCK goes low, indicating that the CDC aknowledges the request. The 4-bit bus direction is set to CDD to CDC.
|'''Type'''
* 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.
|'''Direction'''
* HOCK goes high and the CDC reads the status data (A).
|'''Description'''
* CDCK returns high.
|-
* HOCK returns high.
| 1
* CDCK goes low, the B word is ready.
| SGND
* The cycle continues on for 10 words.
| Power
 
| -
(The delay here is not necessary, but it can be seen on the NeoGeo CD and is caused by the system ROM preparing stuff).
| Ground
 
|-
* HOCK goes low and the 4-bit bus direction is inverted (CDC to CDD). The command data is set (red A).
| 2
* CDCK goes low, indicating that the CDD has read the data (A).
| SVCC
* HOCK returns high.
| Power
* CDCK returns high.
| -
* HOCK goes low, the B word is ready.
|
* The cycle continues on for 10 words.
|-
 
| 3
==Status data (green)==
| VCC
 
| Power
* A: Status - 1=playing, 2=seeking, 4=paused, 9=idle, 14=stopped
| -
* B: Status
|
* C: Minutes high digit
|-
* D: Minutes low digit
| 4
* E: Seconds high digit
| WFCK
* F: Seconds low digit
| Clock
* G: Frames high digit
| Output
* H: Frames low digit
| Write Frame Clock
* I: Extension
|-
* J: Checksum (see below)
| 5
 
| GND
==Command data (red)==
| Power
 
| -
* A: Command
| Ground
* B~I: Depends on command
|-
* J: Checksum (see below)
| 6
 
| SCOR
==Checksum==
| Pulse
 
| Output
The checksum digit is the sum of all 9 previous digits, + 5, XOR 15, modulo 15: ((sum + 5) ^ 0xF) & 0xF.
| Subcode sync
 
|-
==Commands==
| 7
 
| MUTE
See [[CD drive commands]].
| ?
|
|
|-
| 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
|}


==Adjustments==
==Adjustment pots==


To do !
To do !


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

Latest revision as of 18:48, 22 June 2019

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

The part that makes you wait and fails in CD systems. The ones used in the NeoGeo consoles are very similar to those found in the Sega CD. They're basically enhanced audio CD drives, which are also able to read CD-ROM data tracks.

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 CD 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

Adjustment pots

To do !

Retrieved from "https://wiki.neogeodev.org/index.php?title=CD_drive&oldid=6502"