DESCRIPTION
The GP521 is a general purpose controller/memory chip in tended for use with audio signal path circuits in programmable hearing instruments.
The GP521 uses a flexible communication standard which allows room for future growth in programmable functions for hearing instruments. The communication with the program unit is over a bi-directional serial data link. Error detection circuitry is used to avoid undesired changes in programmed settings.
An information transfer dialogue consists of the address and data for a register sent to the GP521 and the register contents returned by the GP521. The function controlled by an output of the GP521 is defined by the signal path circuit allowing current controlled parameters. The relationship between the GP521 register addresses and the function on the signal path circuit is defined by a data file in the programming unit. With this format, any software developed for the GP521 can be used for future generations of Gennum’s controller/memory circuits and audio signal path circuits.

FEATURES
• general purpose
• EEPROM non-volatile memory
• 8 programmable current sink (PCS) control outputs
• can be configured with 6 PCS outputs for hearing instruments (two switchable, four non-switchable)
• status register
• data transmission error detection
• synchronization of GP521 internal clocks with program unit clock