I have an application to decode an FSK signal on a VHF carrier. In the past
I would have used an EXAR XR2211A FSK demodulator chip feeding a
microcontroller but I assume with the proliferation of DSP's, the days
of
these chips and ones like them are numbered. Hoping to make the leap into
the 21st century, I started investigating the incorporation of a DSP into my
design. What I found was a bewildering expanse of offerings.
I started with Microchip because I use their conventional microcontrollers
but their offerings seem to be aimed more at process control than audio
applications. My next favorite stop is Analog Devices which has a lot of
audio related processors but they seem to be aimed at large scale
applications with many inputs and outputs and corresponding large packaging.
I looked at Cirrus logic but their processors have high resolution for high
end audio applications. After spending some time on the Freescale site I
located a chip that they were recommending for modem applications including
some relatively slow modes. I got excited until I downloaded the data sheet
and discovered that it comes in a 144 lead package.
Is there such a thing as a simple DSP for low end audio applications that
meets the following criteria?
- 1-2 audio channel capability
- 16-24 bits of additional I/O
- One each of SPI, UART & possibly USB I/O
- Free or inexpensive development software
- Easily prototyped with a demo board or using a generic breadboard
- Libraries are available for low end modem or audio frequency
tasks
- Documentation that can guide rather than bewilder a novice
- Not nearing the end of its life cycle
I wish I had a handle on my memory requirements but I don't have a clue.
There will be a small configuration routine, the FSK signal will be
demodulated, an error checksum calculated, a 4x20 alphanumeric LCD driven
and the data passed via the serial or USB port or both. As a starting point,
if I wasn't trying to do the demodulation in the controller, I would be
using a PIC18F2550 with 16K of program memory and 2K of RAM.
Somebody please point me in the direction of a suitable DSP! Thanks!
Regards,
George
