|
Sample-Rate Converter
Audio interface converter based on FPGA Spartan-3E (XC3S250E) is implemented in
the media-player. Three I2S streams are separated from the data format packet
256 bit wide stream (generated by the Processor Blackfin ADSP-BF533 for AD1836)
for the subsequent transformation to S/PDIF. Multiplexed commutation between
incoming and outgoing streams is possible. The incoming I2S stream is forced for
the oversampling to 48 kHz.
Sample-Rate Converter is implemented as two CIC-filters. The incoming stream of
any frequency (44.1 kHz, 48 kHz, 96 kHz) is M times interpolated to high frequency
(50 MHz) and is N times thinned by the decimator. M and N coefficients are
selected by the detector based on input frequency so that output system frequency
is 48 kHz.
FPGA also implements the accompanying logic for ADSP-BF533 processor: keyboard
debounce, IR-commands detector, processing of signals coming from optic encoder
(volume control), frame buffer for LCD-monitor, S/PDIF-transmitter (CS8427)
control logic and «glue-logic» for connection of NAND-Flash and Wi-Fi modules.
Specifications
| FPGA-type |
Spartan-3E 250 (XC3S250E) |
| Outside IP-cores |
were not applied |
| Interfaces |
SPORT (BlackFin audio) |
| IP cores |
- I2S
- SPI
- glue logic
- sample-rate converter
|
| Peculiarities |
SNR > 80 db |
| Design tools |
ISE 9.2, Modelsim XE, Synplify 8.6 |
| Lead time |
1,5 months |
|
|
|
