{"id":17427368,"url":"https://github.com/danmar/mobilephone","last_synced_at":"2025-09-13T01:07:11.956Z","repository":{"id":7706596,"uuid":"9071360","full_name":"danmar/mobilephone","owner":"danmar","description":"mobile phone","archived":false,"fork":false,"pushed_at":"2013-12-13T18:47:13.000Z","size":7988,"stargazers_count":3,"open_issues_count":0,"forks_count":3,"subscribers_count":2,"default_branch":"master","last_synced_at":"2025-03-28T00:37:07.844Z","etag":null,"topics":[],"latest_commit_sha":null,"homepage":null,"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/danmar.png","metadata":{"files":{"readme":"README.md","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":"2013-03-28T06:23:36.000Z","updated_at":"2022-01-09T08:13:25.000Z","dependencies_parsed_at":"2022-09-13T05:40:52.473Z","dependency_job_id":null,"html_url":"https://github.com/danmar/mobilephone","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/danmar/mobilephone","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danmar%2Fmobilephone","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danmar%2Fmobilephone/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danmar%2Fmobilephone/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danmar%2Fmobilephone/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/danmar","download_url":"https://codeload.github.com/danmar/mobilephone/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/danmar%2Fmobilephone/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":274903094,"owners_count":25371084,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","status":"online","status_checked_at":"2025-09-12T02:00:09.324Z","response_time":60,"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":"2024-10-17T06:23:15.406Z","updated_at":"2025-09-13T01:07:11.909Z","avatar_url":"https://github.com/danmar.png","language":"C++","funding_links":[],"categories":[],"sub_categories":[],"readme":"\r\n# mobilephone\r\n\r\nProject to build a simple mobile phone (GSM). The mobile phone will handle\r\nvoice calls.\r\n\r\nI will use off-the-shelf electronic components.\r\n\r\nThe software development and electronic components is sponsored by\r\nEvidente.\r\n\r\n## Progress\r\n\r\n### Step 1 : GSM chip\r\n\r\nI bought a SM5100B GSM chip, a simple evaluation board for this chip, and a\r\nGSM antenna. The chip understands AT commands.\r\n\r\nI bought a normal prepaid comviq sim card.\r\n\r\n![alt text](http://github.com/danmar/mobilephone/raw/master/images/1-mini.png \"Chip\")\r\n\r\n### Step 2 : Setup\r\n\r\nI connected everything and tried to setup the chip for the GSM card. It was\r\nquite straight forward.\r\n\r\nBy using AT commands from my PC I can send/receive SMS and dial/answer voice\r\ncalls (however I have no audio yet).\r\n\r\n### Step 3 : Audio\r\n\r\nThe plan in this \"step\" is to connect a microphone and speaker. The datasheet\r\nfor SM5100B has reference designs for connecting microphone and speaker that\r\nI will try to use.\r\n\r\nAccording to the datasheet, the speaker can be connected directly to output\r\npins on the chip.\r\n\r\nBefore I had any parts, I wanted to \"dry run\" the audio. When a voice call is\r\nmade, it should be possible to measure something on the speaker output. I made\r\nthis connection:\r\n  GSM chip speaker output =\u003e voltage divider =\u003e microphone input on my PC\r\n\r\n![alt text](http://github.com/danmar/mobilephone/raw/master/images/3a-mini.png \"Connection\")\r\n\r\nOscilloscope view when I whizzle in the calling telephone\r\n\r\n![alt text](http://github.com/danmar/mobilephone/raw/master/images/3b.png \"Oscilloscope view\")\r\n\r\nAudio recording when I say \"test, test\". It's very faint.\r\n\r\nhttp://github.com/danmar/mobilephone/raw/master/images/3.wma\r\n\r\n### Step 4 : Connecting the microcontroller to the GSM chip\r\n\r\nHere I have connected a MBED microcontroller to the UART0 port on the GSM chip:\r\n\r\n![alt text](http://github.com/danmar/mobilephone/raw/master/images/4-mini.png \"MBED\")\r\n\r\nTo start with the MBED just sends \"AT\" commands and then receive the response \"OK\".\r\n\r\n### Step 5 : Prototype box\r\n\r\nI bought a small box. The microphone and speaker I bought was connected. The\r\nreference circuits from the datasheets worked fine!\r\n\r\nInternal view:\r\n\r\n![alt text](http://github.com/danmar/mobilephone/raw/master/images/5b-mini.jpg \"Internal\")\r\n\r\nExternal view:\r\n\r\n![alt text](http://github.com/danmar/mobilephone/raw/master/images/5a-mini.jpg \"External\")\r\n\r\nThe dialer is both used to dial numbers and to answer / hang up. By spinning the dialer\r\nall the way twice you answer and hang up.\r\n\r\nIt works when using a AC/DC power adaptor. But unfortunately it doesn't work well from a\r\nbattery. I use a normal 9V battery right now. This may be too weak.\r\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fdanmar%2Fmobilephone","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fdanmar%2Fmobilephone","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fdanmar%2Fmobilephone/lists"}