CD/DVD mode selection control using laser diode voltage

1. An apparatus, comprising:

a first device having an analog output;

a second device having a digital input and an analog input; and

an interface circuit coupling the analog output of the first device to the digital input and the analog input in the second device, the interface circuit including circuitry to use a single control signal from the analog output of the first device to control the digital input and the analog input in the second device;

wherein the second device includes an optical sensor for converting optical signals reflected by a CD or a DVD into electrical signals;

wherein the digital input in the second device is a mode selection signal and is configured to select one of a first mode or a second mode in the optical sensor; and

wherein the first mode is to detect CD laser light and the second mode is to detect DVD laser light, the CD laser light and DVD laser light having distinct wavelengths.

2. The apparatus in claim 1 wherein the first device and the second device are components of a DVD/CD player.

3. The apparatus in claim 2 wherein the first device is a digital signal processor.

4. The apparatus in claim 3 wherein the second device is an optical pick-up unit.

5. The apparatus in claim 4 wherein the apparatus comprises a karaoke player.

6. The apparatus in claim 1 , the second device including a CD laser and a DVD laser, wherein the analog input in the second device is for activation of one of the CD laser and DVD laser for reading data from a CD or a DVD.

7. The apparatus in claim 1 wherein the analog output of the first device has a logic relationship with respect to the digital input of the second device.

8. The apparatus in claim 1 wherein the interface circuit comprises at least first circuitry for generating the analog input from the analog output of the first device, and second circuitry for generating the digital input from the analog input.

9. The apparatus in claim 1 wherein the first device and the second device have a master-slave relationship with the first device being the master and the second device being the slave.

10. The apparatus in claim 1 wherein the second device has a laser diode for reading at least one of a DVD and CD and a sensor for translating optical inputs, comprising laser diode generated light reflected from the DVD or CD, into electrical outputs that are sent to the first device to complete a feedback loop.

11. A method for controlling different inputs, comprising:

coupling an analog output of a first device to an interface circuit;

coupling the interface circuit to an analog input and a digital input of a second device, wherein the digital input in the second device is a mode selection signal;

controlling the analog input and the digital input of the second device using a control signal from the analog output of the first device; and

in accordance with the mode selection signal, selecting one of a first mode and a second mode in a sensor in the second device, wherein the first mode is to detect infrared laser light waves reflected from a CD and the second mode is to detect red laser light waves reflected from a DVD.

12. The method of claim 11 further comprising coupling a second interface circuit between the analog input and the digital input.

13. The method of claim 11 wherein the analog output of the first device has a logic relationship with respect to the digital input of the second device.

14. The method of claim 11 wherein the first device is a digital signal processor (DSP) and the second device is an optical pick-up unit (OPU) of a DVD/CD player.

15. The method of claim 11 further comprising selecting one of a red laser to emit light waves to read a DVD and an infrared laser to emit light waves to read a CD.

16. The method of claim 11 further comprising changing the analog output of the first device from a first value into a second value in response to a feedback signal from the second device.

17. The method of claim 11 further comprising changing the analog output in the first device in response to a change in mode detected by the second device.