fpga +cpu + wireless

On a sunny day (Mon, 15 Sep 2003 14:01:17 -0500) it happened Srikanth Anumalla wrote in :

If your pressure sensors have analog output, then why use FPGA? Use a PIC micro with build in AD and 4 channel input mux.

3 of these or one with an external mux, use the serial port of the PIC or make your own protocol or whatever. 12F675 is only 8 pins DIL, has a 10 bits AD with 4 input mux, internal oscillator, costs 2 dollars, so 4 of these set you back 8 dollars and the microchip tools are free from Why use FPGA?

oscillator,

are

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).

Thanks in advance Srikanth

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

The solution seems promising, what kind of wireless technology can be used ? can I use 802.11 or blue tooth or any other.

Whatever you can find a USB device for. 802.11 and blue tooth should both work. You might have problems getting documentation on how to program these devices though. I would suggest starting with one that has Linux drivers. Those usually have open documentation and the Linux driver source is always a good starting point for questions.

Regards, Andras Tantos

I'm not sure what your cost requirements are, but for getting off the ground one recently released development platform comes to mind.... check out Omniwerks

who offers a complete 802.11 FPGA/Embedded CPU development kit, with board/software/IP. They use the Nios CPU & uc/OS II operating system on the software side.

Jesse Kempa Altera Corp. jkempa at altera dot com

Hi Srikanth

Have you thought about using CPLDs? Xilinx offer the coolrunner II kits for around $49. I have bought one for my own development purposes and it seems to be fairly straight forward in use and has many I/Os.

Naveed