stickjam
Well-known member
This is probably way out of many of the regular denizens of the board, but I'm hoping there are some digital gurus in here to at least generate some ideas and/or point me to some online communities that may be more into this stuff. Anyway, I'm working on an digitally-controlled audio device. (I'll share more details once I figure out what it's going to be! :green
I've got most of the audio path worked out, but the problem I'm trying to solve in this question is the digital one...
In essence, this box will contain bunch of voltage-controlled elements that run off an array of inexpensive DACs. I want to be able to control this box from a laptop at a distance--even if need be, through a single return channel in an XLR stage snake. This would indicate a serial protocol such as EIA-485 since it's already in use in theatrical lighting and other stage/automation applications.
For the DACs, there are a couple options that look most promising. Either has unique interface demands. What I'm looking for are ideas in how to interface to either chip:
Option 1: TLC7226 Quad Parallel 8-bit DAC
This will need a circuit to take the serial data stream and convert it to a parallel format. The ideal output would be at least 8-bits of address (parameter number), 8-bits of data (parameter value) and a one bit strobe. The strobe should pulse whenever a new address/data combination arrives. The address would select the DAC to update and the strobe would update it with the value on the data bus. Alternatively, I could easily throw in some logic to deal with only 8 bits of data and a strobe line.
Option 2: TLC5628 Octal Serial 8-bit DAC
This one seems really cool because it halves chip-count and cost on the DACs, but how would I daisy-chain a bunch of these together and be able to address them through a single serial data stream? I'd also need to somehow convert EIA-485 to the 12-bit data stream the DACs are looking for.
I realize a microcontroller might be the best solution for this, but I can't help thinking that it might really be overkill--that there might already be some other kind of interface chip that would help construct either option without having to deal with programming firmware, burning FPGAs or the like. (Like a serial memory controller??)
Like I said, if you know of any other community I can ask this question of, or if you know anyone else that may be able to give me some guidance, let me know.
Thanks!
--Bob
I've got most of the audio path worked out, but the problem I'm trying to solve in this question is the digital one...In essence, this box will contain bunch of voltage-controlled elements that run off an array of inexpensive DACs. I want to be able to control this box from a laptop at a distance--even if need be, through a single return channel in an XLR stage snake. This would indicate a serial protocol such as EIA-485 since it's already in use in theatrical lighting and other stage/automation applications.
For the DACs, there are a couple options that look most promising. Either has unique interface demands. What I'm looking for are ideas in how to interface to either chip:
Option 1: TLC7226 Quad Parallel 8-bit DAC
This will need a circuit to take the serial data stream and convert it to a parallel format. The ideal output would be at least 8-bits of address (parameter number), 8-bits of data (parameter value) and a one bit strobe. The strobe should pulse whenever a new address/data combination arrives. The address would select the DAC to update and the strobe would update it with the value on the data bus. Alternatively, I could easily throw in some logic to deal with only 8 bits of data and a strobe line.
Option 2: TLC5628 Octal Serial 8-bit DAC
This one seems really cool because it halves chip-count and cost on the DACs, but how would I daisy-chain a bunch of these together and be able to address them through a single serial data stream? I'd also need to somehow convert EIA-485 to the 12-bit data stream the DACs are looking for.
I realize a microcontroller might be the best solution for this, but I can't help thinking that it might really be overkill--that there might already be some other kind of interface chip that would help construct either option without having to deal with programming firmware, burning FPGAs or the like. (Like a serial memory controller??)
Like I said, if you know of any other community I can ask this question of, or if you know anyone else that may be able to give me some guidance, let me know.
Thanks!
--Bob
