Robertsonics designs high performance embedded audio players and processors, used worldwide by professionals and hobbyists alike.
Keep things simple. 18 trigger inputs connect to your contact closures to fire specific MP3 Tracks (up to 192kbps stereo) on a microSD card, or to implement transport functions like next, previous, stop, random play, volume etc. Simple, ASCII-based serial protocol makes it easy to control from an Arduino. Text init file allows setting the serial baud rate and alternate trigger functions. Special trigger modes allow simple logic without the need for an external microcontroller. Firmware upgradable.Read More
Carina is the only Blackfin development board designed from the ground up for audio. Everything you need for a professional stereo effects processor. Sporting a 400MHz Blackfin, 256MB of external SDRAM, balanced stereo inputs and outputs, 24-bit ADC/DAC >98dB SNR, and sample rates up to 96KHz. A 26-pin IDC connector provides plenty of general purpose I/O for user interface controls. A “plug-in” style software framework for VisualDSP lets you immediately focus on algorithm development.Read More
For professional and demanding applications. The worlds least expensive truly polyphonic embedded audio player – allowing you to play and layer up to eight CD quality (16-bit, 44.1kHz, stereo) tracks independently. Additional trigger modes and settings provide pause and resume capability, specify track ranges for stop, random and sequential play. Trigger inputs support passive (contact closure) or active (3.3V / 5.0V logic) as well as inverted modes on an individual basis. MIDI serial option provides velocity-sensitive triggering of up to 1000 tracks. Stereo line-level output, on-board 2W mono amplifier and speaker connector for true single-board operation. Firmware upgradable.Read More
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In most cases, it’s probably safe to increase the number of voices to at least 10. 8 was chosen as the default to be compatible with the slowest microSD card I’ve encountered. Without a scope, you’ll know when you’ve hit the limit for your card when you start to hear crackling or pops after layering the max number of tracks. For those of you with a scope, PC15 (pin 4 on the STM32F4) duty cycle indicates the amount of time taken by the mixer. 100% is bad.
The limiting factor for the number of voices is what I call the “access time” of the microSD media, which is different than the sustained bitrate used for the speed ratings. Unlike sequentially reading a single file, mixing WAV tracks involves reading a small number of sectors from files spread all over the FAT disk. The critical issue is the time it takes between asking for a new sector read and when the card actually starts providing that data. I’ve not found this parameter to be documented by the microSD card manufacturers, so you’ll just have to experiment with it.