High speed ADC with USB interface

skrev i meddelandet news:41f3934e$0$803$ snipped-for-privacy@news.optusnet.com.au...

I doubt that you will find this ADC/USB/Storage on a single chip. With 4 Mhz sample rate and 12 ´bit resolution you need 48 MHz operation for a serial interface so it is likely you need a parallell interface.

I assume you store the samples first and then send it over USB. Then you need 8 kB of storage for the samples. Is it acceptable to use a UART at 115 kbps which connects to a USB-Serial bridge? You can transfer 4kW in about 1 second?

You would be looking for a micro with

• DMA capability for 4 Mtransfer/s

• 16 bit Bus

• 8 kB extra SRAM (16 kB min)

• USB interface, or connection to an external UART-USB bridge

• External ADC

The AT94K05 FPSLIC has enough RAM and can directly interface to the ADC using the FPGA area, but lacks the USB.

Analog Devices do some evaluation boards for some of their ADCs which you can interface to their 'USB FIFO' board, might be suitable, although I think the ADCs in question are far faster than 4MSPS.

4K

WoW now that would be something for sure - geeeesh as I ponder the frailties of using a 60KVA 3-phase UPS as a paperweight !

--
Regards
Mike
VL Commodore, Calais VL Turbo FuseRail that wont warp or melt !
http://niche.iinet.net.au

I'm looking for 12-16bit ADC with 4MHz samplingrate capable of storing 4K samples, with USB interface to transfer data to a PC.

Any recommendation ?

My appologies.!.. Altough I said ADC, what actually I mean an ADC board, not necessary single chip.

My corrected question is;

I'm looking for 12-16bit ADC Board with 4MHz sampling rate capable of storing 4K samples, with USB interface to transfer data to a PC.

A 12-16 bit ADC with 4 Mhz sampling rate requires a minimum throughput of 48 Mb/s, and a maximum of 64 Mb/s. This means you must have a Hi-Speed USB 2.0 IC, which is capable of the theoretical maximum of 480 Mb/s.

One candidate is SMSC's GT3200. It has a 16-bit parallel interface, thus it is possible to interface it with any modern microprocessor. For the ADC unit, I'd look at Analog Device's ADC selection matrix. They have at least a

16-bit 65 MSPS (Million samples per second) device and a 16-bit 3 MSPS device. If your sampling rate of 4 Mhz is absolute, the 65 MSPS is the nearest suitable 16-bit one. The interface is parallel, thus it would be directly compatible with the GT3200.

If a lower sampling accuracy is enough, AD also offers a 12-bit and 14-bit

10 MSPS devices, both with parallel interface. The upper 4(2) bits of the USB unit could be used for signalling, if necessary.

I have only experience with the AD's ADC units, and they've been positive experiences. Dunno about the GT3200, but you could try checking them out.

-Antti Keskinen

48 2.0

If the board needs/has a sample buffer, then there is no need for the high speed. You get 4k samples and then upload it over 12 mbps USB at leasure.

/Ulf