On Wed, Jan 12, 2011 at 8:36 PM, Jamie Morken <jmor...@shaw.ca> wrote: > > Hi, > > I am interested in helping out with making some new gnuradio hardware that is > compatible with the USRP daughterboards. I worked with Matt doing CAD on the > original gnuradio project hardware and have since then made lots more boards > including a cyclone 3 board. > > Here is a possible hardware configuration: > USB 3.0 transceiver IC or USB 3.0 microcontroller > Altera Cyclone3 FPGA > highspeed DAC/ADC > > If we use just a single channel ADC and DAC (ie half a USRP v1) then we can > get away with a smaller/cheaper FPGA and have a cheaper/simpler board that > can be paralleled if needed (ie. two boards hooked up to USB 3.0)
The idea of USB3 is nice for the future, but I don't think there are enough peripherals out there yet to make a good board. I can't really find anything that's not completely preliminary and somewhat cheap. I'd like to propose what I think may be a good compromise. Altera Cyclone IV EP4CGX15 FPGA, Analog Devices AD9861 MxFE, USB2 microcontroller (for reprogramming the FPGA) in an ExpressCard/34 format. The FPGA has a hard PCIe 1.1 x1 lane with a hard IP core for PCIe connectivity. The PCIe interface has an extremely low latency and pretty high throughput - ~200MB/sec full duplex (after overhead and whatnot). The FPGA would be mostly empty since the PCIe core is hard. If the F169 package is used, it should be compatible with up to a EP4CGX30 which would give 80 18x18 multipliers and over 1Mbit of embedded memory. The ExpressCard format can fit into desktop PC's with simple and cheap adapters, or into laptops which have ExpressCard slots. ExpressCard has both an x1 PCIe connection as well as a USB 2.0 connection. I imagine a small USB 2.0 micro used for FPGA configuration and, possibly, a secondary way for samples to enter/exit the FPGA for different use cases (similar to the original USRP). But the main purpose would be for reconfiguration of the FPGA. Frequency synthesis can be an optional part of the assembly. I imagine a relatively inexpensive VCTCXO (2ppm accuracy?) along with an Si5338 clock synthesis chip. The idea, though, is to be completely optional for those who really want it. Otherwise, the FPGA PLL's can probably be good enough for most people. For connectors, 2 HDMI (commodity and cheap, twisted pair, shielded and rated to relatively high frequencies) - one for analog/baseband signals, one for digital I2C/SPI comms. Goes to a daughterboard carrier which can hold the daughterboard and a digital IO port expander for controlling the RX/TX IO [0:15] pins for the db connectors. I think the high bandwidth, low latency, and low CPU utilization of PCIe is very attractive. The main downside to the parts are the BGA components which can be daunting for hobbyists, but toaster ovens with PID controllers can really do a pretty amazing job. I'm not sure if this is a dealbreaker or not. I'm very interested to hear other people's opinions as to proposed interfaces, platforms, architectures, and connectivity. Jamie, I hope you don't see this as a hijacking of your original e-mail. I am particularly interested in your response. Brian _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio