CD drive: Difference between revisions

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[[File:Cd2_cdboard1.jpg|thumb|right|CD2 CD drive board.]]
[[File:Cd2_cdboard1.jpg|thumb|right|CD2 CD drive board.]]


Or "CD drive". The part that fails before everything else in [[CD systems]]. Also see [[optical pickups]].
The part that fails before everything else in [[CD systems]]. 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 ?


It is made of:
The control board has:
* A 4-bit maskROM MCU (Sony CXP5084), taking care of sequencing and communication (command execution and status report).
* A 4-bit maskROM 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 and sled motor driver (Rohm BA6396).


==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 and a logic analyzer.
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| Clock
| Clock
| Output
| Output
| Tells the CDC when to change HOCK
| Communication clock to CDC
|-
|-
| 2
| 2
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| Clock
| Clock
| Input
| Input
| Tells the CDD data is ready on D0~3
| Communication clock from CDC
|-
|-
| 6
| 6
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| Clock
| Clock
| Output
| Output
| I2S bit clock, should be 44100 * 32 = 1.4112MHz
| Serial bit clock, should be 44100 * 32 = 1.4112MHz
|-
|-
| 12
| 12
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| Data
| Data
| Output
| Output
| I2S data
| Serial data
|-
|-
| 13
| 13
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|-
|-
| 14
| 14
| MUTE?
| D/M ?
| Signal
| Signal
| Input
| Output
| Put low to gate SDATA ?
| Data/Music. Low during music playback ?
|-
|-
| 15
| 15
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|}
|}


Some signal has to be "D/M", an output which indicates if SDATA is audio or data. There's a /RESET somewhere also.
Missing: /RESET, C2PO, and 16MHz.


==Communication==
=Communication=


CDD (CD Drive) to CDC (CD Controller, motherboard) communication uses an uncommon scheme, and is handled by the [[system ROM]]. {{Chipname|NEO-MGA}} takes care of the I/Os through registers {{Reg|REG_CDDCTRL}}, {{Reg|REG_CDDINPUT}}, {{Reg|REG_CDDOUTPUT}}.
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}}.


[[File:Cdunit4bit.png]]
[[File:Cdunit4bit.png]]
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* 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]] program preparing stuff).
(The delay here is not necessary, but it can be seen on the NeoGeo CD and is caused by 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 inverted (CDC to CDD). The command data is set (red A).
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* The cycle continues on for 10 words.
* The cycle continues on for 10 words.


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


* A: Status
* A: Status - 1=playing, 2=seeking, 4=paused, 9=idle, 14=stopped
* B: Status
* B: Status
* C: Minutes high digit
* C: Minutes high digit
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* J: Checksum (see below)
* J: Checksum (see below)


===Command data (red)===
==Command data (red)==


* A: Command
* A: Command
* B~H: Depends on command
* B~I: Depends on command
* I: Checksum (see below)
* J: Checksum (see below)


===Checksum===
==Checksum==


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


===0: STATUS===
See [[CD drive commands]].
No parameters.
 
===1: STOP ALL===
No parameters. Stops CDDA playback, disk spin, and sets drive in data mode.
 
===2: TOC COMMAND===
D: Command code:
 
====0: GET POSITION====
MSF in status will be the current position from the beginning of the CD (absolute).
====1: GET TRACK POSITION====
MSF in status will be the current position from the beginning of the track (relative).
====2: GET TRACK NUMBER====
Minutes in status will be the current track.
====3: GET CD LENGTH====
MSF in status will be the total CD length.
====4: GET FIRST AND LAST TRACKS====
Minutes in status will be the first track (normally 1), seconds will be the last.
====5: GET TRACK NUMBER====
MSF in status will be the start of the desired track. If the track is a data track, the frames high digit's fourth bit will be 1 (OR 8).
 
===3: PLAY===
* B: Minutes high digit
* C: Minutes low digit
* D: Seconds high digit
* E: Seconds low digit
* F: Frames high digit
* G: Frames low digit
 
Starts playing audio.
 
===4: SEEK===
* B: Minutes high digit
* C: Minutes low digit
* D: Seconds high digit
* E: Seconds low digit
* F: Frames high digit
* G: Frames low digit
 
Sets pickup at desired position.
 
===6: PAUSE===
Pauses CDDA playback (disk keeps spinning).
 
===7: RESUME===
Resumes CDDA playback.
 
===8: FAST-FORWARD===
Unknown.
 
===9: REWIND===
Unknown.
 
===10: INIT===
Sets pickup at lead-in ?
 
===12: CLOSE===
Closes the tray on the front-loading NeoGeo CD.
 
===13: OPEN===
Opens the tray.


==Adjustments==
==Adjustments==

Revision as of 09:51, 10 January 2017

File:Cd2 cdboard1.jpg
CD2 CD drive 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 maskROM 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 and sled motor driver (Rohm BA6396).

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.

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 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.

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) 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 (green A). Diagram fix: A should be ready on CDCK low.
  • HOCK goes high and the CDC reads the status data (A).
  • CDCK returns high.
  • HOCK returns high.
  • CDCK goes low, the B word is ready.
  • 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).

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

Status data (green)

  • A: Status - 1=playing, 2=seeking, 4=paused, 9=idle, 14=stopped
  • 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)

  • A: Command
  • B~I: Depends on command
  • J: 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.

Adjustments

To do !

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