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how to achieve continuous transfers with ft2232h and libftdi

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how to achieve continuous transfers with ft2232h and libftdi

Steffen Mauch
Hi,

I use the FT2232H with MPSSE for SPI transfer.
Connected to the SPI bus is a Analog Digital converter which also has  
an SPI interface.

The ADC is able to transfer 125000 * 3 Bytes per channel. It has 8  
channels.
The FT2232H could transfer up to 30 Mbit and there shouldn't be any  
problems with the bandwidth.


I am not so familiar with the usb protocol :-/ so what is the best way  
to achieve a continuous reading.
I mean, if I read 4096 bytes for example then I want to read another  
4096 bytes just after recieving the "old" 4096 bytes.
If there is not much space between this action, I could read everything.
I know that this could only work, if nothing else is connected to this  
usb host, because otherwise some other peripherial could be active.  
Then I have to wait and I don't have a continuous measurement.


My idea was to set with ftdi_set_latency_timer(&ftdic, xxx) the  
latency to for example 2ms and calculate with the clock of spi how  
much I should read in 2ms.

Is this possible or won't it work?
Or is there another (maybe better) possibility how to achieve my goal?

Thanks.


Mit freundlichen Grüßen
Steffen Mauch

-------------------------
cand. B.Sc. Steffen Mauch

Digital Communications & Signal Processing Lab
Fakultät Computer & Electrical Engineering

Hochschule Furtwangen University
Robert-Gerwig-Platz 1
78120 Furtwangen

Tel    +49 (0)7723 920 2342
Fax    +49 (0)7723 920 2802
Cell   +49 (0)1511 235 2355

[hidden email]
www.DCSP.HS-Furtwangen.de


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