AES audio to I2S or LJ bit stream

[Thomas Blake]

Hi,

I need to convert AES/EBU serial audio to I2S serial audio (or merely to left-justified serial data) and I'd like to use a 16F877 for it. The process is simple: convert bits 4-28 of four parallel biphase-mark (pseudo-Manchester) streams to 4 bit-serial streams for feeding an 8-channel DAC, while keeping track of a the block start sync nibbles in bit cells 0-3. I'd be hitting the interrupt pin 394K times per second at a crystal of 12.288MHz. The numbers work out OK for the interrupt handler timing. It's a strange job for a PIC but I think it's plenty fast enough. Anyone else ever tried this?
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This message was ported from CCS's old forum
Original Post ID: 13690

[Charlie U]

:=Hi,
:=
:=I need to convert AES/EBU serial audio to I2S serial audio (or merely to left-justified serial data) and I'd like to use a 16F877 for it. The process is simple: convert bits 4-28 of four parallel biphase-mark (pseudo-Manchester) streams to 4 bit-serial streams for feeding an 8-channel DAC, while keeping track of a the block start sync nibbles in bit cells 0-3. I'd be hitting the interrupt pin 394K times per second at a crystal of 12.288MHz. The numbers work out OK for the interrupt handler timing. It's a strange job for a PIC but I think it's plenty fast enough. Anyone else ever tried this?

I haven't tried this, but your numbers don't look like they'd work. First, with a 12.288MHz xtal, your instruction cycle is 3.072MHz. If you are truly hitting the interrupt at 394kHz then you will only have approx. 7.8 instruction cycles per interrupt. The CCS compiler uses approx 40 instructions total to enter and leave an interrupt so you would need to code the interrupt yourself. I've probably misinterpretted something, so a little more info would help.
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This message was ported from CCS's old forum
Original Post ID: 13695

[joe06]

I think you need a FPGA to make this ...


:=Hi,
:=
:=I need to convert AES/EBU serial audio to I2S serial audio (or merely to left-justified serial data) and I'd like to use a 16F877 for it. The process is simple: convert bits 4-28 of four parallel biphase-mark (pseudo-Manchester) streams to 4 bit-serial streams for feeding an 8-channel DAC, while keeping track of a the block start sync nibbles in bit cells 0-3. I'd be hitting the interrupt pin 394K times per second at a crystal of 12.288MHz. The numbers work out OK for the interrupt handler timing. It's a strange job for a PIC but I think it's plenty fast enough. Anyone else ever tried this?
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This message was ported from CCS's old forum
Original Post ID: 13752

[Miguel Martin]

:=Hi,
:=
:=I need to convert AES/EBU serial audio to I2S serial audio (or merely to left-justified serial data) and I'd like to use a 16F877 for it. The process is simple: convert bits 4-28 of four parallel biphase-mark (pseudo-Manchester) streams to 4 bit-
......

Hi. Your application is very similar to an development I made for process a 200 Kbits/s frame, (same as E1 framing, but only 3 time slots of 64 kbits.

I use, with success, a 16F876 with clock 20 Mhz.
But I process this frame with external frame alignment signal detection (shift register + PLD). On pic is implemented sync declaration algorithm plus other process, (drop & insert channel service and pulse sync generation for trigger the audio codecs G.711.

I use one pic to receive and 1 pic for transmit. I don't use the interrupts. The pic is nearly to limit for process 192 Kbits frame on real time.

The pic is good, but not magic...
Regars.

Miguel Martin
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This message was ported from CCS's old forum
Original Post ID: 13753