Browse Prior Art Database

Sound Generation Circuit

IP.com Disclosure Number: IPCOM000050270D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Eggebrecht, LC: AUTHOR

Abstract

In some applications, it may be desirable to be able to generate a plurality of different sounds which can be determined by program control. The figure shows a circuit used to generate sounds and music and to drive an 8 ohm speaker with approximately 1 watt of power. The speaker diaphragm may be controlled by three different control points, namely, the timer/counter channel output, the timer input clock gate control, and the ORed programmable input/output (I/O) port bit. Proper program control of these three control points allows the generation of complex waveforms for driving the speaker diaphragm.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 65% of the total text.

Page 1 of 2

Sound Generation Circuit

In some applications, it may be desirable to be able to generate a plurality of different sounds which can be determined by program control. The figure shows a circuit used to generate sounds and music and to drive an 8 ohm speaker with approximately 1 watt of power. The speaker diaphragm may be controlled by three different control points, namely, the timer/counter channel output, the timer input clock gate control, and the ORed programmable input/output (I/O) port bit. Proper program control of these three control points allows the generation of complex waveforms for driving the speaker diaphragm.

One channel of the timer/counter circuit, which may be an Intel 8253-3 chip, is capable of driving the speaker through the timer output signal. The timer counter can be programmed into one of six different modes of operation and thus generate a large set of waveforms to the speaker. The modes are: (1) BCD Counter.

(2) Programmable One-Shot.

(3) Rate Generator.

(4) Square-wave Rate Generator.

(5) Software-Triggered Strobe.

(6) Hardware-Triggered Strobe.

The timer counter channel is driven by a 1.19 MHz clock from the system CPU clock. This input clock is further controlled by a gate signal on the timer/counter device which turns on and off the clock to the timer/counter. The timer/counter is also controlled by a programmable I/O port bit from a programmable peripheral interface (PPI) module, such as the Intel 8255A-5. Thus, the program can set...