{"id":19641707,"url":"https://github.com/pdmccormick/de2-polyphonic-audio","last_synced_at":"2026-06-12T19:33:20.717Z","repository":{"id":11735567,"uuid":"14261513","full_name":"pdmccormick/de2-polyphonic-audio","owner":"pdmccormick","description":"Polyphonic tone generation demo for the Altera DE2 FPGA dev board with NIOS II soft core processor.","archived":false,"fork":false,"pushed_at":"2013-11-09T17:37:31.000Z","size":224,"stargazers_count":1,"open_issues_count":0,"forks_count":0,"subscribers_count":2,"default_branch":"master","last_synced_at":"2025-02-26T23:15:54.983Z","etag":null,"topics":[],"latest_commit_sha":null,"homepage":"","language":"C","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/pdmccormick.png","metadata":{"files":{"readme":"README.txt","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null}},"created_at":"2013-11-09T17:26:53.000Z","updated_at":"2020-11-04T19:17:55.000Z","dependencies_parsed_at":"2022-09-11T14:31:15.870Z","dependency_job_id":null,"html_url":"https://github.com/pdmccormick/de2-polyphonic-audio","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/pdmccormick/de2-polyphonic-audio","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/pdmccormick%2Fde2-polyphonic-audio","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/pdmccormick%2Fde2-polyphonic-audio/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/pdmccormick%2Fde2-polyphonic-audio/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/pdmccormick%2Fde2-polyphonic-audio/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/pdmccormick","download_url":"https://codeload.github.com/pdmccormick/de2-polyphonic-audio/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/pdmccormick%2Fde2-polyphonic-audio/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":34260309,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-05-26T15:22:16.424Z","status":"online","status_checked_at":"2026-06-12T02:00:06.859Z","response_time":109,"last_error":null,"robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":[],"created_at":"2024-11-11T14:10:11.109Z","updated_at":"2026-06-12T19:33:20.679Z","avatar_url":"https://github.com/pdmccormick.png","language":"C","funding_links":[],"categories":[],"sub_categories":[],"readme":"DE2 Polyphonic Audio Demo\n=========================\n\nPeter McCormick\npeter@pdmccormick.com\n\n\nIntroduction\n------------\n\nThis is a small demo of driving the audio outputs on a DE2 FPGA dev board\nrunning a NIOS II soft core processor, by polyphonically mixing pitches from\nover two octaves of a C major scale (with the notes controlled by the slider\nswitches.)\n\nThis code is placed in the public domain, provide 'as is' and without any\nwarranty whatsoever. The user assumes all risk by running or using it.\n\n\nGetting Started\n---------------\n\nUsing the Altera Monitor Program, create a new C language project and add all\nthe C (*.c) and assembly code (*.s). Under 'Memory Settings', set the \"Start\noffset in device (hex)\" fields to '1000' for both the .text and .data section\n(this offset makes room for the exception handler code.) Download to your DE2\nboard, plug in speakers or headphones, compile and run.\n\nUse the slider switches from right (SW0 as C4) to left (SW17 as F6) to play\nscales, chords or melodies.\n\nWARNING: Beware that the audio played is at full volume (amplitude), so either\nuse speakers with a volume control or do not immediately put your headphones up\nto your ears until you know just how loud that is.\n\n\nIdeas\n-----\n\nChange mono output to something interesting in stereo.\n\nSave 48KB of memory by noticing that the second half of the `sine_wave` array\nis a reflected, negated version of the first.\n\nImplement a multi-thousand sample software FIFO that feeds into the hardware\nFIFO to ease timing restrictions.\n\nHandle audio input and output together (whether in pass-through or simply up to\na higher layer of software.)\n\nGenerate harmonically richer tones than pure sine waves.\n\nImplement a mixing strategy more sophisticated than just averaging.\n\nAdd effects like chorusing or delay.\n\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpdmccormick%2Fde2-polyphonic-audio","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fpdmccormick%2Fde2-polyphonic-audio","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fpdmccormick%2Fde2-polyphonic-audio/lists"}