Re: gEDA-user: Trouble with an usb oscilloscope

["Robas, Teodor" <teodor.robas@xxxxxxxxx>]

Hello Eric,

The ISP1581 has an 8 KB of FIFO. 6KB are allocated as a double buffer 
for isochronous transfer via DMA. The DMA circuit does the job of 
getting the data from outside, put it into RAM and validating it for 
transmission. The samples does not need to reach into the ATmega162 mcu RAM.

What worries me is that the DMA may try to send something outside, 
creating a conflict with the A/D outputs (this DMA has a lot of other 
options specially for computer hard disk devices). This is my assumption 
for not getting enough speed. But until now no smoke.


Eric Winsor wrote:
> Teodor,
>
> I have not used your particular chip but have done USB with Cypress's 
> 8051 based controllers.  Are your samples going to a RAM and then sent 
> across the USB bus from there or are you sending the sampled data 
> directly to the USB bus buffer?
>
> Eric Winsor
>
>



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