terjeio 134 Posted October 16, 2015 Share Posted October 16, 2015 My (crazy) project is getting closer to completion so time to start a project topic. I have verified my Tiva C based controller design and are now waiting for PCBs - will arrive from China in a few days. My background is from Radio/TV servicing and medical electronics, but for the last 25 years I have mainly been working on a large database application written in OpenEdge. Two years ago my preamp that I made some 30 years ago started to fail due to the rubber based switches rotting (a bit like my brain these days...). Since I did not want to buy one I decided to make a new - again with no mechanical parts in the audio path. A lot has happened since back when I was involved in electronics, and I have spent some time doing research for what components are now available - to many one may argue. I decided to use a CPLD programmed in VHDL for the switching logic, high quality analog switches (my original design employed 40 series CMOS for these) and a VCA (voltage controlled amplifier) for volume control. I did not want to introduce a MCU because I believed I would get into trouble with the clock signal interfering with the audio... Anyway, my new design was successful and has now been in service for nearly two years. After doing this I took an interest in learning about microprocessors again, I started out with Atmel/Ardouino and Energia but I found that combination a bit lacking - no easy way to do debugging was a showstopper for me. I found the TI processors more appealing, CCS allows me to get my hands dirty on "bare metal" and a decent debugger makes life easier. So, here I am making another iteration of my preamp - this time involving no less than four TI processors. I have decided to post my project under the Tiva C header since it is the main workhorse, but the three other MCUs are 430s. Ok, enough rambling - here are the main components I have designed: Raspberry PI power switch - PC-style startup/shutdown, may be controlled over I2C or from a front panel switch. IR Remote Control - RC5 protocol. Main controller - Tiva C based, custom UI library and support for Keystone DAB radio. Preamp board, 5 line inputs with the option of switcing one to phono (magnetic cartridge - vinyl is getting popular again), DAB option, I2C control and still a VCA based volume control. I have recently switched to KiCad as my EDA, I did use Zenith PCB earlier but I am a bit scared to continue using that as it is licensed on a yearly basis (even if it is free) - who knows when it wil not be supported anymore. KiCad is open software and does not suffer from any limitations to number of pins or board size. Attached are the design files I have made for the Preamp board - the design is still to be verified, I will do that when I see how the controller board works out when arriving from the fabricator. 3D view from my KiCad design - I am too lazy to make my own 3D files so it is somewhat incomplete. There is a TI processor hidden on the bottom side, as is the KeyStone radio module. If everything goes to plan I will post about the bits and pieces that makes up the complete project. I even have mechanical design files (Vectric format) that may be used to make files in order fabricate the enclosures on a CNC-machine. Ok, enough for this time. Terje PreAmpBoard.zip bluehash, dubnet, oPossum and 2 others 5 Quote Link to post Share on other sites
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