Design support

The LID/TOC switch.

Every normal CD has a Table Of Contents or TOC. This table provides information about the start time, stop time of a track on the disc.

The CD system reads out such TOC and uses it for navigation on the disc. It now know fairly well how many “grooves” to jump in order to find a track.

Also per direct it knows the amount of tracks and the total time. This is shown on the display after TOC reading.

If a disc is taken from the turntable and a new disc is placed without updating the TOC the system will have navigation problems as the information in the memory is not consistent with the information coming from the disc during jumps.

A TOC is read:

After power on.

After coming back from standby

After a read TOC request via the LID/TOC switch.

This button can be hooked up via 2 pins on the display PCB. See PCB layout

A CDR disc that was not finalized does not contain a TOC, it does contain a Pre-TOC recorded in a area that normally can’t be read-out by an ordinary CD player. The CD-PRO2LF can however read this pre-TOC information and even use it for navigation.

Lastly the CD-PRO2LF can also navigate on disc’s without any TOC or pre-TOC. Jump actions may take however longer.

Please note that “copy protection systems” often deliberately produce erroneous TOC information in order to mislead CD recorders. The software in the CD-PRO2LF system is updated as much as possible for the correct handling of such errors without influence on the normal operation of the system.

Practical tip:

Simply make next to your CD module a button with the LID/TOC switch and just push it after you replaced the disc. The disc will spin and the new TOC will be displayed in a matter of seconds.