![]() ![]() This is generally possible using Arduino AVR hardware, where some assembly level programming enables a timer to toggle a digital output at the required frequency. The clock signal may be supplied from external hardware, or it can be created by the MCU with a timer capable of generating the 4MHz clock. This gives a frequency range at maximum input clock rate of 122Hz to 125kHz (a range from roughly A2, two octaves below middle A, to 5-6 times the generally accepted limits of human audio perception). Thus the overall divider range is from 32 to 32768. With an external clock frequency of 4MHz, each channel’s frequency is arrived at by dividing the external clock by 32 and then dividing the result by N. A value provided in a control register for that channel (called N).The frequency of the square waves produced by the tone generators on each channel is derived from two factors: If multiple independent ICs are interfaced, then the ICs CE line is used to select the right device so that the data lines are shared. The IC is a 16 pin DIP package with the following pinout: SignalĪctive low Chip Enable (connect to GND or MCU It was extensively used in early game consoles, arcade games and home computers. Its main historical application was the generation of music and sound effects in microprocessor systems. ![]() Simultaneous sounds on one audio output.1 noise generator (white noise and periodic noise at 3 different frequencies).3 programmable square wave tone generators (122Hz to 125kHz).The SN76489 Digital Complex Sound Generator (DCSG) is a TTL-compatible programmable sound generator chip from Texas Instruments. The SN76489 is one such IC that is still available at a very modest price and is easily interfaced to modern microprocessors. The easiest way to do this to toggle a single I/O pin to generate a square wave but there are some retro sound ICs that allow us to do much better for a minimal investment. Most computer games from the 80’s are recognizable by the bleeps and bloops they produced for sound. ![]()
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