--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Mon, Jul 18, 2016 at 10:10 PM, Manuel A. Fernandez Montecelo manuel.montezelo@gmail.com wrote:
2016-07-18 20:57 Luke Kenneth Casson Leighton:
I suppose that using custom co-processors/accelerators is an alternative possibility for video/display, but probably not easy. Some uses of the SoC (e.g. micro-servers) probably don't care anyway,
yeah they wouldn't. that U500 would actually make a great EOMA200 processor.
but I understand that it's part of the EOMA68 standard.
it's not that, it's that the power requirements to run a separate video IC are just as heavy if not heavier than the actual processor itself. even just running the PCIe lanes between the video and main processor - driving the voltages up and down - can take up a significant proportion of the EOMA68 power budget.
Yeah, got that.
What I meant is that even if many people who would use it as a micro-server wouldn't be worried about the lack of video acceleration, it always was (AFAIK) a hard requirement for the EOMA68 standard itself -- being able to render video at FullHD or similar.
nono, not at all, that's a misunderstanding: the actual requirement is about the maximum resolution that the LCD interface has to be driven at (1366x768 for type II 5mm cards, 1920x1080 for type I 3.3mm cards).
an FPGA-based card using a zynq 7030 could do 18-bit or just 15-bit RGB/TTL and not have any kind of acceleration at all.
there's even an ATSAM4 that operates at only 200 mhz which has an RGB/TTL interface: that would qualify... it's just that pricing is completely mad (somewhere around $9!) so it's not financially viable or justifiable.
the IC1t was *barely* able to drive 1024x768 16bpp @ 50hz due to the internal memory bandwidth: amazingly they used the OpenCores LCD/VGA library but they didn't update its memory bandwidth. they were only expecting people to run it @ 640x480 @ 32bpp, or at most 800x600 @ 24bpp, but because the OpenCores VGA driver is publicly documented i was able to work out how to put it into 8-bit mode (2 bits red, 3 bits green, 3 bits blue) and because of the reduced internal bus bandwidth of dropping to one byte per pixel i was actually able to drive all the way up to 1440x900! there is even a monochrome mode but i didn't investigate that.
so yeah, point is: Full HD (or any kind of 2D or 3D or Video acceleration at all) is *not* part of the EOMA68 hardware standard.
at some point i really want to do an Ingenic M150 EOMA68 card and see how low the BOM can really be pushed. it'll be a 2-layer PCB (!) because the M150 is designed for 2-layer. their EVB is postage-stamp-sized, it's pretty amazing.
l.