Electronics-Lab.com Blog

Sebastian built an experimental record/looper circuit, resulting in some interesting sample contortionism. [via]

This circuit currently has a few ways to manipulate audio. These are:

A record button allows the user to sample incoming audio to a RAM buffer

A potentiometer sets the input level

A potentiometer sets the sample rate / pitch for playback. The changing of sample rate can be recorded if desired, by physically changing the position of the pot during recording.

The address lines A0 – A18 can be manipulated ie. moved around, removed, replaced, giving a wide range of effects such as stuttering, repeating and basic granulation.
Although this does not sound like heaps of manipulation, keep in mind that this circuit can absolutely mangle a sound beyond recognition. The ADC is running at its maximum speed, and as such the sample rate can be varied greatly for example.

Audio looping & manipulation in RAM - [Link]

Learn how to interface PCF8583 Real Time Clock with an AVR microcontroller. Source code is included.

avrprojects.net writes:

The PCF8583 is a clock/calendar circuit based on a 2048-bit static CMOS RAM organized as 256 words by 8 bits. Addresses and data are transferred serially via the two-line bidirectional I2C-bus. The built-in word address register is incremented automatically after each written or read data byte. Address pin A0 is used for programming the hardware address, allowing the connection of two devices to the bus without additional hardware.The built-in 32.768 kHz oscillator circuit and the first 8 bytes of the RAM are used for the clock/calendar and counter functions. The next 8 bytes may be programmed as alarm registers or used as free RAM space. The remaining 240 bytes are free RAM locations.

Real Time Clock PCF8583 - [Link]