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Subject: Re: DMA Operation???
From: George Styles (
Date: 2002-10-18

Thanks, thats made things a lot clearer. I didnt grasp the point that the
data goes from the SH to the MAS via a standard UART serial connection... :)

Can i ask one more thing please? is the DMA clever enough to not send data
through faster than the MAS can use it? i assume the MAS can say 'enough for
now' and the DMA pauses until the MAS says it is ready for more data (or
does so via the UART by setting RTR to no!)?

> I take your point about having to frame align my 'beep', you are quite
> > correct - bit of a challenge that :) i guess we are looking at doing a
> > little DMA to finish the current frame before the 'beep' dma,
> > followed by
> > the remaining real MP3 frames, including dealing with track boundaries
> > etc...
> Yup. Quite a tricky task.

How about this? when we want a beep, we

1. stop the current DMA
(assumes that DMA is active all the time either transfering data to serial0
or waiting for serial0 to become ready),

2. Read the address it got up to thanks

Page was last modified "Jan 10 2012" The Rockbox Crew