A buddy of mine had a cheap Phillips boombox that included a USB port to play music (mp3 and wma files) from a flash ("thumb") drive. I just built a custom boombox based on a Sony car receiver with aux inputs. I'd like to add a USB input and circuit that would perform DAC and route it to the radio's aux input. Is there a chip or IC (and a simple circuit, I hope) that will do this conversion? Thanks!
If what you mean, is retrieve the data from the USB flash drive, and stream it out as audio, then no, this is not a simple circuit at all.
What happens is that the flash drive is just a file storage device, like a hard disk. It doesn't do anything with the data on it except send it to the host. The USB Input on the Boombox reads the files, interprets them (probably only MP3/WMA/WAV), decodes them if neccesary (the hard bit!) and THEN feeds them to it's DAC circuitry.
A USB DAC is different. What that does is appear to a host as a "USB Audio Device", a standard USB protocol for sending sound. The host then sends raw audio data to the DAC, where it is decoded.
So, at the very least, a microcontroller is involved to read the flash drive. Then, you have to have some method of decoding the data. There's a few chips that you can send MP3 data to, and it will decode. WMA is available also but less easy to find, and I don't think I've seen one handling WAV. The Boombox probably uses some Microcontroller/DSP combo to do this job.
edit: You might think "Well how do those thumb drives with inbuilt MP3 players work, then?" The answer is simple. They have an ASIC built in which is a FLASH controller, USB interface, MP3/WMA decoder and DAC all in one. The data is usually read directly from the flash when the player is playing standalone, and the USB interface only used when it is connected to a computer.
What happens is that the flash drive is just a file storage device, like a hard disk. It doesn't do anything with the data on it except send it to the host. The USB Input on the Boombox reads the files, interprets them (probably only MP3/WMA/WAV), decodes them if neccesary (the hard bit!) and THEN feeds them to it's DAC circuitry.
A USB DAC is different. What that does is appear to a host as a "USB Audio Device", a standard USB protocol for sending sound. The host then sends raw audio data to the DAC, where it is decoded.
So, at the very least, a microcontroller is involved to read the flash drive. Then, you have to have some method of decoding the data. There's a few chips that you can send MP3 data to, and it will decode. WMA is available also but less easy to find, and I don't think I've seen one handling WAV. The Boombox probably uses some Microcontroller/DSP combo to do this job.
edit: You might think "Well how do those thumb drives with inbuilt MP3 players work, then?" The answer is simple. They have an ASIC built in which is a FLASH controller, USB interface, MP3/WMA decoder and DAC all in one. The data is usually read directly from the flash when the player is playing standalone, and the USB interface only used when it is connected to a computer.
there was a ready made board that read audio files (mp3 wma wav etc.) from the memory card then decode them and play sound. it uses PIC thing which the code could be upgraded later. ask these guys and sure they know how to read out the music from your flash drive. i will when i have time and will let you guys know.
anyone know other kind rather than pic thing? let me know.
anyone know other kind rather than pic thing? let me know.
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