Video generator in hub?
Wuerfel_21
Posts: 4,507
in Propeller 2
Hmm, that p2 stuff is intresting! Anyway, from what i could find out with such crapulent search function is that the video generators will be in every cog like the p1.
But when does anyone need more then 1 or 2 video outputs? So just make one or two big video generators that the cogs will share to generate lots of things like hdmi and 16 bit vga and some better incarnation of composite/broadcast video!
But when does anyone need more then 1 or 2 video outputs? So just make one or two big video generators that the cogs will share to generate lots of things like hdmi and 16 bit vga and some better incarnation of composite/broadcast video!
Comments
Composite, Component, and other formats / modes will be done in software. Nice thing about that is really sweet monochrome output can happen on a single pin.
It's my understanding signals can go in or out of the chip using a more generic capability. WAITVID doesn't actually exist on P2. Implementing it will look something like streaming + an interrupt to manage that stream.
And given how many times we've all thought about how cool it would have been to take input in the same way, this all seems like a very good direction.
As for HDMI, that requires an IP discussion along with a lot of complexity and another development path branch. Can't see that happening.
P2 has been an analog design from the get go. It's pretty easy to run the analog signals to an HDMI chip and go from there.
I don't think so, Counters are moved to Smart Pins, and Video support is changed.
I think the PLL and carrier adders are gone, but there is a streaming ability to Analog DACs, and also Streaming to LCD (wide digital paths + Clocks)
(IIRC Chip said those would be NCO clocked.)
VGA and Component video should be well supported, but PAL Composite may need considerable software effort.
HDMI needs LVDS drivers, so that is never going to be inside P2. There are LCD-Datapath (WideData+CLK) to LVDS chips that could do that.
Yes the multiple high speed DACs will set P2 apart from many MCUs.
I have not seen numbers from the OnSemi process relating to actual the DAC performance from the latest deign files & approach ?
Details like crosstalk levels may need to wait for a real device ?
HDMI needs LVDS drivers, so that is never going to be inside P2. There are LCD-Datapath (WideData+CLK) to LVDS chips that could do that.
It may be possible to do a kind of lvds using the fast DACs that will be available.
It could get challenging, as the second PLL has gone too.
It may need 2 COGS, one for Sync + Luminance, and a separate Chroma cog maybe using CLUT table NCO lookup ? That's probably not going to change colours very rapidly., and will place constraints on the main PLL / Xtal
85.896MHz and 114.528MHz are a couple of choices for 3x and 4x of a 8x Chroma Scan rate, with the latter able to use a 4x Chroma Xtal.
Having DAC will make for a much improved signal, similar to the one the last FPGA image did, sans the cool color management features.
Some of this depends on the streaming capabilities, and maybe the smart pins. We got the interrupts needed to manage the stream in ways similar to what WAITVID did.
PAL is gonna come down to jitter and timing just like P1. If we can hold jitter to a smaller amount, it's likely we get good PAL.
Personally, I'm looking forward to SD component and HD component. The former runs at the slow scan rates which maximizes what can be done in tandem with the display, and the latter is a nice VGA alternative.
I'm reminded by a couple weekends ago where I had to (very painfully) turn down a free Amiga 1200 due to Amiga's Achilles' heel of being locked into a 15.72kHz HSYNC. Playing with that toy would've meant acquiring an expensive adapter, or rummaging around for a multisync monitor.
As for the P2, even component video is disappearing from displays, the old workshop LCD TV notwithstanding, so having a path forward is important.
> HDMI is considered legacy anyway with DisplayPort as its successor.
That may be true in the computer space but it definitely is not for consumer electronics. Virtually every piece of consumer electronics you can purchase today that outputs video does so via HDMI/miniHDMI. This interface will be supported for a long time. And even if it's supplanted by DisplayPort, DP has a backwards compatibility mode for HDMI.
> As for HDMI, that requires an IP discussion along with a lot of complexity and another development path branch.
There's a difference between carrying the HDMI badge and technically being capable of it. If the P2 just happened to be powerful/fast enough to move electrons in an HDMI-compatible way if programmed to do so, I can't see it wouldn't be on Parallax to license the IP. The SPDIF object on P1 is a good example of what I'm thinking of.
But I think Displayport vs. HDMI and IP licensing is a moot point, so on to Wuerfel_21's original question:
My admittedly naive reading of the HDMI spec is that there's a relatively simple I2C control channel and not-at-all-simple TMDS scheme for the pixel data. The I2C part should be cake for the P2. The pixel data on the other hand has 8b/10b encoding, differential signalling, and would be clocked at 10x the pixel clock for a given resolution. All three are probably impossible:
- The 8b/10b TMDS encoding of HDMI is unique to it, I believe. A simple programming interface would give us a value-to-bitstream translation table that we could set up for a serial driver to base its bit patterns on, but this is almost certainly not flexible enough for all serial output needs. I'm not even sure if serial driver hardware is still on the table for the smart pins.
- I think we've been told that differential signalling is not going to happen, as well.
- Even something as simple as 640x480 works out to 250MHz+ clock rate for pixel data. That's more than the expected P2 clock and I'm not sure we have any indication any serial driver built into smart pins will run faster than the internal clock.
I'd love to be wrong about this but it's not looking good for HDMI or any digital video on the P2. Sorry, Wuerfel_21. Of course, by declaring it impossible I'm just guaranteeing that someone will figure out a way to do it...
Not directly driven, but there are already DVI designs for P1, using devices like TFP410 and a SSD device
See
http://forums.parallax.com/discussion/comment/1089660/#Comment_1089660
The streaming modes in P2 should be able to interface to parts like TFP410, and give 2 chip solutions.
If you want to pump serious pixels on a high res display, the P2 is unlikely to be the first stop anyway, and the Small SBCs of the RaspPi2 ilk, keep getting faster & more RAM.
I would expect more P2's to be sold doing direct-lcd connections, via the streaming feature.
(goes and looks at the data sheet for the TFP410...)
Oh! I see. Parallel digital pixel data off chip to the TFP410, or something like it, which can serialize to DVI (and possibly HDMI) speeds. Not too bad.
HDMI - 3 x RCA
HDMI - 5 x RCA adapter cables,
HDMI to 5 RCA RGB Component Converter Adapter HDTV Video Audio AV Cable
It seems these are for Set Top Boxes, where they now start to avoid installing Component connectors, and instead MUX those Analog options onto a HDMI connector under menu control, likely inside the chipset.
Chinglish says
"Compatible only with any analog component (YPbPr) input device such as projectors, HDTVs, etc. - Notes: This cable is not a converter and will not convert HDMI digital signals to analogue signals."
There are also
HDMI Male to VGA Female Adapter
and HDMI Male to VGA Cables
Given HDMI connectors are smaller and easier to fit than RCA, this could be a compact way to get practical P2 resolution options on a small PCB.
A little more elusive, is a pin-out mapping spec or standard on these ?
Need to get some time to look further into it.
I would be glad to adopt that Amiga (or any Amiga). :-)
Is it still available???
I wonder if it is a full converter, or something like simple NPN buffers to drive the loads, or CAPs ? ?
I guess trying it on a HDMI signal would give some indication.
The component video ones seem to target Set Top boxes, so that may be a growing cable market as they remove the RCA & use cables instead - problem is, finding if there is any standard mapping. (or as you find, no direct connect )
Also, the OP is asking for a digital solution that will work with HDMI inputs on monitors/TVs, not the analogue inputs. So, what we should be looking for is a cheap analogue to HDMI converter that can take the Prop's analogue (VGA/composite) output and match it to a HDMI monitor.
I second the cheap converter. If it's placed on a PCB with the P2, nice, short, well designed analog connections should leave us a pixel perfect signal.
Yes, that was my point.
These adapter cables I mentioned are "just using the same connector", that connector is smaller & cheaper than component video connectors.
A ready-made cable is cheaper and neater than some custom-connector ( there is a confusion trade off in here *)
The question I'm trying to find details on, is are those Set-Top adapter cables, (HDMI-5xRCA) all using a common pin-mapping standard ?
* Another cable-bridge option would be VGA-5 RCA, but that uses a more expensive and larger PCB connector, but would have a more stable pin-map and cause less user confusion.
There seem to be plenty of HD15 - 3 RCA cables.
What use is that for an HDMI monitor/TV?
The other cable (HDMI-5xRCA) is for when they have a pre HDMI TV, that has Component Video in.
The STB will have a menu option to change from HDMI to "just using the same connector" Component Video.
The VGA is a female intended to go to a VGA Monitor.
But hey, there are NO pin connections to the RGB pins (1/2/3). No wonder I couldn't get a resistance measurement!
My intention was to use an HDMI connector on my pcb to output VGA to the appropriate pins. I wanted a smaller connector than VGA and a cheap converter cable
Also digital is better for text output. Photos over hdmi vga and component are hard to tell apart.
Vga and component are really hard to tell apart.
If one really wanted hdmi output then I think raspberry pi makes more sense.
Still if you want digital video can use tfp410 for low cost to add hdmi/dvi output. Actually a dvi connector has rgb analog pins too so might pair well with props analog output. Gives use option of dvi, dvi to hdmi cable, or dvi to vga adapter.
It's a good plan...
What pins did they connect ? - or did the RCA cables go nowhere ?
And none of that does anything for an HDMI monitor!
Thanks for investigating this, btw