Continuous High Speed Digital Acquire- Monitor SPI data lines

[Allan_M]

Hi

I need to monitor a serial interface that runs at 5-10Mhz of SPI protocol.

I am using a PCI 6534 with upto 20MHz capability. I have access to Chip Select, Data In, Data Out and SCLK.

Valid Data is sent when Chip Select is low.

I have tried start trigger (ACK) when chip select low and stop trigger (REQ) when chip select high however have been unsuccessful to acquire all data.

I need  to be able to trigger off the chip select line going low and then read digital lines (Data In , Data Out, SCLK) until chip select then goes high.  

Once i have acquired all data (Packets of 8 bytes - 40bytes), i will then need to decode the output.

Can anyone help please?

[Seamus_C]

Hi Allan,

I think you should use a USB-8451.  This device is designed specificly for what you are trying to do.  The 8451 can interface with clock rates of up to 12MHz.  Also with the 8451, your interface can be located much more closely SPI device rather than using a PCI card.

If you have any more questions please let me know.

Seamus

NIUK

Message Edited by Seamus C on 06-13-2007 08:00 AM

[Allan_M]

Seamus

I have previously used a 8451 device to drive a SPI circuit, however for this application i just need to monitor 4 digital lines, (i cannot interface or drive the lines i have to monitor / decode them).

I have found many examples of acquiring data from digital lines however i need to trigger of a signal then start acquring all data on the other lines.

I can use digital start trigger for chip select falling edge and stop trigger on the Chip Select rising edge. When trigger found data of 4 lines needs to be stored then decoded.  

Thanks