Hi everybody,
right now I am designing two boards for a mobile audio box. One carrier board for power supply (Step-up powered by 2x18650 LiIon Batteries with balancer and charger IC or a laptop battery charger) and one board with bluetooth module, mikrocontroller (conrols charging, bettery level, muting and so on) and amplifier.
Right now I am finished with the layout, but to add additional possibilities (one tweeter and one woofer, two fullrange loudspeaker, use it as an amp for stationary loutspeaker...) I am thinking about adding a DSP like the ADAU1702.
The problem here is, that I haven't found a cheap (or easy) solution with digital out. It seems that the cheap modules from ebay with the CSR8645 have principally the possibility, but there is a software on the ROM which doesn't allow I2S output.
The second solution would be to use the analog way. Cheap bluetooth module with differential DAC output --> use only one line since ADAU1702 has only single ended ADC inputs --> analog input of TPA3116.
Is it worth to buy a more expensive bluetooth receiver (or is there a cheap solution?) with digital out, or would you stick with the "analog" way?
I am not planning to build highend speakers, I just want to try different chassis in different boxes and present friends on birthday with one. To avoid passive filters after the amp I really would like to have a DSP on board.
Any suggestions?
All the best!
right now I am designing two boards for a mobile audio box. One carrier board for power supply (Step-up powered by 2x18650 LiIon Batteries with balancer and charger IC or a laptop battery charger) and one board with bluetooth module, mikrocontroller (conrols charging, bettery level, muting and so on) and amplifier.
Right now I am finished with the layout, but to add additional possibilities (one tweeter and one woofer, two fullrange loudspeaker, use it as an amp for stationary loutspeaker...) I am thinking about adding a DSP like the ADAU1702.
The problem here is, that I haven't found a cheap (or easy) solution with digital out. It seems that the cheap modules from ebay with the CSR8645 have principally the possibility, but there is a software on the ROM which doesn't allow I2S output.
The second solution would be to use the analog way. Cheap bluetooth module with differential DAC output --> use only one line since ADAU1702 has only single ended ADC inputs --> analog input of TPA3116.
Is it worth to buy a more expensive bluetooth receiver (or is there a cheap solution?) with digital out, or would you stick with the "analog" way?
I am not planning to build highend speakers, I just want to try different chassis in different boxes and present friends on birthday with one. To avoid passive filters after the amp I really would like to have a DSP on board.
Any suggestions?
All the best!
I think aptX decoding is a must-have BT audio feature, so you might end up having to go with a more expensive solution anyway.
You might consider one of the Bluegiga modules from Silicon Labs or look into offerings from Microchip, both of which are available through Mouser. I have yet to work with either, so take the above for what it's worth.
You might consider one of the Bluegiga modules from Silicon Labs or look into offerings from Microchip, both of which are available through Mouser. I have yet to work with either, so take the above for what it's worth.
Hi, thanks for your reply 
I spent the last few days with researching. I think I found the best solution for me.
I found only three bluetooth modules with I2S and APT-X support.
I couldn't find much about the BC127 so I won't take it.
The WT32i is directly buyable with and without APT-X (~6€ more) but doesn't give out the masterclock.
RN-52 seems to be the only module which is common in some open source projects and produces masterclock. Unfortunately it is not possible to buy it somewhere already with APT-X license installed.
Besides the RN-52 I will go for an ADAU1702 as Audio DSP. With the freeDSP adapter (20€) I can directly use the Analog Devices SigmaStudio software for live configuration or boot from a small EEPROM. It additionaly provides an ADC I can use for line-in (and an additional I2S input for an additional external input).
I just have to put an analog switch for the clock in front of the mclk-in and I can shut the bluetooth module down while feeding the DSP per external device.
As amplifier I will use two TAS5751M. With the DSP I can easily configure them as 2.1 , 1.1 or 2.0 system.
I will give feedback as soon as the project makes progress.
I spent the last few days with researching. I think I found the best solution for me.
I found only three bluetooth modules with I2S and APT-X support.
I couldn't find much about the BC127 so I won't take it.
The WT32i is directly buyable with and without APT-X (~6€ more) but doesn't give out the masterclock.
RN-52 seems to be the only module which is common in some open source projects and produces masterclock. Unfortunately it is not possible to buy it somewhere already with APT-X license installed.
Besides the RN-52 I will go for an ADAU1702 as Audio DSP. With the freeDSP adapter (20€) I can directly use the Analog Devices SigmaStudio software for live configuration or boot from a small EEPROM. It additionaly provides an ADC I can use for line-in (and an additional I2S input for an additional external input).
I just have to put an analog switch for the clock in front of the mclk-in and I can shut the bluetooth module down while feeding the DSP per external device.
As amplifier I will use two TAS5751M. With the DSP I can easily configure them as 2.1 , 1.1 or 2.0 system.
I will give feedback as soon as the project makes progress.
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