Re : fpga +cpu + wireless

[Ben Nguyen]

Andras,

Couldnt a simple RS-232 to USB chip (ex. www.ftdichip.com/FT2232C.htm )
be used instead of the Cypress SL811HS? Then go wireless from there
like you mentioned.

Most PICs, AVR, etc have the RS232 built in, and you dont need an
external bus or any additional I/Os.

Im not sure about the "host" thing.

Ben

The reason I went for fpga was to have wireless networking (802.11)
Actually, the sensors are 3-4 miles apart, I need the data until a
base station from where I will transfer the data to the internet.
the base station is located in the filed and will be 1-2 miles distant
from each sensor. So how do I transfer (in realtime) the data until the
base station from the sensor. Is it possible with PCI micro.
Please suggest me if there is a better solution other than fpga cpu
for doing this (wireless networking).

Doing wireless with FPGA is not easier (nor harder) than with CPUs or MCUs.
You probably will end up using some kind of off-the-selves wireless card and
connect it to your custom application. Of what I understand of your
application probably a wireless USB card would be the best for your
application. Processing power is not an issue in your case. In that case you
need to choose (or implement) a USB host controller but for control even an
8-bit CPU (PIC or AVR or whatever) should be adequate. I don't know of any
8-bit micro that has an USB host (not function!) controller, but there's a
USB interface IC from Cypress, the SL811HS, that can be used as both a host
and a slave controller. So, my suggestion would be:

- Use an 8-bit microcontroller with an external bus (68HC11 from Motorola)
or one with enough of I/O pins (ATmega from Atmel) and probably a with
built-in A/D for the pressure sensors.
- Use the SL811HS from Cypress to implement the USB host controller
- Stick a wireless USB adapter to the unit to implement wireless
- For 1-2 miles you probably need high-gain, directed antennas so choose an
adapter that has external antenna connectivity.

Regards,
Andras Tantos