3 Feb
2021
3 Feb
'21
4:54 p.m.
On Feb 3, 2021, at 5:37 PM, Peter Corlett via cctalk
<cctalk at classiccmp.org> wrote:
On Wed, Feb 03, 2021 at 01:09:50AM -0800, jim stephens via cctalk wrote:
Yes, I noticed the usual suspects are out of stock. Need to look further.
My reaction was similar. I like the dual CPUs, that means one could do hard real time
stuff like wiggling I/O lines (for example DDCMP at a megabit per second) while the other
does buffer management and talks USB protocol. I didn't even realize there's a
small I/O coprocessor, that's neat. The TI engine in the BeagleBone Black has that
sort of thing (a much larger one) which seems very useful if the job is particularly hard.
David Gesswein made great use of that for hard drive emulation. But that's a much
larger and more expensive solution.
paul
On 2/2/2021 11:51 PM, Peter Corlett via cctalk
wrote:
I have now pulled the reference manual to look at the GPIO stuff, and it is
indeed very shiny. There's only space for 32 coprocessor instructions per
GPIO bank, but that's possibly all you need: it is apparently possible to
implement a full UART with handshaking in that.
Controlling a floppy is broadly the same level of complexity as a UART, so
it seems that the Pico would be he perfect tool for the job. Now if only I
could actually lay my hands on one... The Raspberry Pi Pico has a similar price to the
Blue Pill and seems a
much better machine for this task, although I haven't combed through its
reference manual yet.
For capture and writing (if that's part of the design) I
heard there's a
dedicated coprocessor for the GPIO pins. It might be useful for offloading
some of the proccessing from some external circuitry to do the capture or
output.