Greaseweazle

[Mattis Lind]

Den ons 3 feb. 2021 kl 18:00 skrev Chuck Guzis via cctalk <
cctalk at classiccmp.org>:

> On 2/3/21 7:14 AM, dwight via cctalk wrote:
> > I'm curious as to how the sampling code looks. Do you use the timers?
> > Dwight
>
> Exactly.  You run the sample timer in "capture" mode using DMA.  There's
> a little trick in this when handling high-denisty fisks in thatthe DMA
> counter is limited to 65K "items" (bytes, words, doublewords), so
> there's a small amount of trickery to get more than 64K samples (grab
> the DMA TC interrupt and restart the transfer 64K down the line).  Other
> than handling the interrupts, the MCU is sitting around staring at navel
> lint.
>

So you store a full track worth of data and then write it to the SD-card.
Then move the flux-length data over to a PC and do post processing there,
right?

Isn't there performance in the CPU to do the actual decoding as well? FM,
MFM, GCR or whatever into data. Find marks, check CRC and all that stuff?

/Mattis