13
Hardware Examples
13 – 5
Note:
The proper loading sequence for boot data must be followed (i.e. the
order in which the host passes bytes to the ADSP-21xx). This sequence is
described in the Chapter 10, “Memory Interface.” To create a file for
booting, use the PROM Splitter utility of the ADSP-2100 Family
Development Software. The PROM Splitter automatically organizes the
bytes in the proper order for booting.
13.3
SERIAL PORT TO CODEC INTERFACE
A codec (COder/DECoder) incorporates analog-to-digital conversion,
digital-to-analog conversion, and filtering in one device. The codec shown
in this example also performs pulse-code modulation (PCM) encoding and
decoding according to the CCITT
µ
-law standard. PCM compresses digital
data so that fewer bits are needed to store the same information. The
ADSP-21xx serial ports have both
µ
-law and A-law companding
(compressing/expanding) capability.
In the example described here, a codec converts its analog input to digital
data, compresses it and sends it serially to the SPORT on an ADSP-21xx
processor. At the same time, the processor sends compressed serial data
via the SPORT to the codec, which expands the data and converts the
result to an analog signal.