04-10-2012, 11:58 AM
REMOTE-CONTROLLED DIGITAL AUDIO PROCESSOR
Digital Audio Processor.pdf (Size: 530.13 KB / Downloads: 103)
These days most audio systems come with remote controllers.However, no such facility is provided for normal audio amplifiers. Such audio controllers are not available even in kit form. This article presents an infrared (IR) remote-controlled digital audio processor. It is based on a microcontroller and can be used with any NEC-compatible fullfunction IR remote control. This audio processor has enhanced features and can be easily customised to meet individual requirements as it is programmable. Its main features are:
1. Full remote control using any NEC-compatible IR remote control
handset
2. Provision for four stereo input channels and one stereo output
3. Individual gain control for each input channel to handle different
sources
4. Bass, midrange, treble, mute and attenuation control
5. 80-step control for volume and 15-step control for bass, midrange and treble
6. Settings displayed on two 7-segment light-emitting diode (LED) displays and eight individual LEDs
7. Stereo VU level indication on 10- LED bar display
8. Full-function keys on-board for audio amplifier control
9. All settings stored on the EEPROM
10. Standby mode for amplifier power control
Circuit description
Fig. 1 shows the block diagram of the remote-controlled digital audio processor. The system comprises Atmel’s AT89C51 microcontroller (IC1), TDA7439 audio processor from SGSThomson
(IC4) and I2C bus compatible MC24C02 EEPROM (IC5). The microcontroller chip is programmed to control all the digital processes of the system. The audio processor controls
all the audio amplifier functions and is compatible with I2C bus. All the commands from the remote control are received through the IR sensor. The audio amplifier can also be controlled using the on-board keys. Microcontroller. The function of the microcontroller is to receive commands (through port P3.2) from the remote handset, program audio controls as per the commands and update the EEPROM. A delay in updating the EEPROM is de- liberately provided because normally the listener will change the value of a parameter continuously until he is satisfied.
Construction
The circuit can be easily assembled on any PCB with IC base. Before you install the microcontroller, memory and audio processor in their sockets and solder the IR receiver module, make sure that the supply voltage is correct. All parts, except the audio processor (TDA7439), require 5V DC supply. The audio processor is powered
by 9V DC. EFY note. Datasheets of all the relevant ICs, source code, etc have been included in this month’s EFY-CD.