Sunday, January 16, 2011

BMD-001 board : high level synopsis

OK, this first part will let us have a look at the board at a high level, in order to have an overview of the board.

This will let us list the major components on it, which will give us an idea of the main functions.

So next is a high level synopsis of the BMD-001 board:

Let’s give some details.

1) Power Supplies
The drive receives its main supplies from the motherboard, with a +12V and a +5V. On board, several sub power supplies are generated. Some are dedicated to digital section and some are dedicated to analog section. Some of theses supplies are critical and have to be clean. A lot of optical drive failures a due to power supplies failure.

2) Oscillator
This is the board’s main reference clock. The main processor generates all the board’s clock from this reference clock.

3) Flash memory
This memory contain the main processor’s firmware, the security keys (the one that links the board to the motherboard), and probably some board’s configuration parameters.

4) EEPROM memory
Generally this type of memory is used to store the most used configuration parameters of systems.

5) The DRAM memory
This is the working memory for the main processor; it runs firmware and stores its variables. The firmware is probably decompressed here from the flash memory by the boot loader, or it can be run from the flash, I don’t know. But for speed constraints it should be ran from DRAM memory.

6) Motherboard connector
This is the communication channel with the motherboard. It is based on an ATA link protocol with other secondary signals.

7) The audio processor.
This one seems to have SACD dedicated interfaces. As it disappears in the BMD-002 board and as the PS3 didn’t support SACD any more, either it does only SACD processing, either it does all sound processing. I don’t know.

8) Optical pickup processor
This component handles extraction data from the optical pickup. It is quite complicated as optical drive implementation is a complex system!

9) BA5888FP
This component is a power driver dedicated for CD and DVD. Motor driving functions are not used, only actuators for focus and tracking are used.

10) BD7956FS
This component is a power driver dedicated for CD, DVD and blue ray. Motor driving functions are used for insertion/ejection, sled and spindle motors. Actuators functions for collimating lens control.

11) Insertion sensor connector
This famous black and red little connector powers the photo led emitter. This part or the tiny cable are quite often failure parts, which results that the disc is not automatically swallowed, but if you push it manually a little bit further, it will be inserted anyway by the insertion mechanism.

12) Insertion motor connector
This connector interfaces the BL1-001 board which carries the loading motor and some mechanical switches that provide information on the disc position and disc format detection (12 or 8 cm).

13) Sled motor connector
This connector directly drives the sled motor, which defines the optical pickup moves.

14) Spindle motor connector
This connector interfaces the MITEC spindle motor board, which carries the motor and its hall sensors.

15) Main processor
This is the heart of the board. It is a complex microcontroller because it handles all functions and its package has a lot of pins. The challenge is to classify by functions his pins, which shall help understand the system.

Enjoy !

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