Design of an Audio Interface for Patmos

Abstract: This paper describes the design and implementation of an audio interface for the Patmos processor, which runs on an Altera DE2-115 FPGA board. This board has an audio codec included, the WM8731. The interface described in this work allows to receive and send audio from and to the WM8731, and to synthesize, store or manipulate audio signals writing C programs for Patmos. The audio interface described in this paper is intended to be used with the Patmos processor. Patmos is an open source RISC ISAs with a load-store architecture, that is optimized for Real-Time Systems. Patmos is part of a project founded by the European Union called T-CREST (Time-predictable Multi-Core Architecture for Embedded Systems).[5] The structure of this project is integrated with the Patmos project: new hardware modules have been added as IOs, which allow the communication between the processor and the audio codec. These modules include a clock generator for the audio chip, ADC and DAC modules for the audio conversion from analog to digital and vice versa, and an I2C module which allows setting configuration parameters on the audio codec. Moreover, a top module has been created, which connects all the modules previously mentioned between them, to Patmos and to the WM8731, using the external pins of the FPGA.