So this seems to only use 3 DMA channels... So by using all 12, you could have 4 additional "cores".
Direct Memory Access computing machine RP2040
11–19 of 19 posts
Re: Direct Memory Access computing machine RP2040
#12This is a rather nice route for malicious code to hide itself... A full trace of what the CPU is up to could never find this.
Re: Direct Memory Access computing machine RP2040
#13Is this the same as the PIO or are those separate?
You can push the DMA access into the PIO for some real fun. Just wish the PIO had a bit more logic/registers. https://gregchadwick.co.uk/blog/playing-with-the-pico-pt4/
> Just wish the PIO had a bit more logic/registers.
Seriously. I'd kill for PIOv2 to be some RV32E subset. Hell, I'd take stripped of normal LD/ST instructions if that made it easier for them.
Re: Direct Memory Access computing machine RP2040
#14Yeah! I/O Channel Processors are back, baby! Now, if only I could find my IBM 370/168 POP manual around somewhere…
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Re: Direct Memory Access computing machine RP2040
#15Earlier quoted context omitted.
You can push the DMA access into the PIO for some real fun. Just wish the PIO had a bit more logic/registers. https://gregchadwick.co.uk/blog/playing-with-the-pico-pt4/
> Just wish the PIO had a bit more logic/registers. Seriously. I'd kill for PIOv2 to be some RV32E subset. Hell, I'd take stripped of normal LD/ST instructions if that made it easier for them.
Ah, you want a Propeller [1]. Basically 64 really smart digital + A/D I/O pins driven by eight 32-bit I/O processors. Enough oomph to build an entire system out of. Quirky, loads of fun if you're into cycle-counting. Not cheap, though--$18 [edit: $13 Digikey] qty 1. :(
Re: Direct Memory Access computing machine RP2040
#16Huh, so DMA controllers do a lot more than I thought they did. A question though: don't we need a "jump if zero" or similar in order to be Turing complete? I see a loop instruction but nothing that could be considered an "if"... https://developer.arm.com/documentation/ddi0424/d/instructio...
Re: Direct Memory Access computing machine RP2040
#17Huh, so DMA controllers do a lot more than I thought they did. A question though: don't we need a "jump if zero" or similar in order to be Turing complete? I see a loop instruction but nothing that could be considered an "if"... https://developer.arm.com/documentation/ddi0424/d/instructio...
The article has a clear paragraph explaining how they do conditional jumps?
Re: Direct Memory Access computing machine RP2040
#18Huh, so DMA controllers do a lot more than I thought they did. A question though: don't we need a "jump if zero" or similar in order to be Turing complete? I see a loop instruction but nothing that could be considered an "if"... https://developer.arm.com/documentation/ddi0424/d/instructio...
The article has a clear paragraph explaining how they do conditional jumps?
Ah. Gotcha. Sorry, my brain cleared between reading the article and the arm documentation.
Re: Direct Memory Access computing machine RP2040
#19Earlier quoted context omitted.
> Just wish the PIO had a bit more logic/registers. Seriously. I'd kill for PIOv2 to be some RV32E subset. Hell, I'd take stripped of normal LD/ST instructions if that made it easier for them.
Ah, you want a Propeller [1]. Basically 64 really smart digital + A/D I/O pins driven by eight 32-bit I/O processors. Enough oomph to build an entire system out of. Quirky, loads of fun if you're into cycle-counting. Not cheap, though--$18 [edit: $13 Digikey] qty 1. :( [1] https://www.parallax.com/propeller-2
That's one good example. The TI Sitara and OMAP PRUs in the Beagle(Board|Bone|etc.) boards are another example.